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  • 1.
    Adbo, Karina
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Andersson, Håkan S.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ankarloo, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karlsson, Jesper G.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Norell, M C
    Olofsson, Linus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Svenson, Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Örtegren, U
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Enantioselective synthetic receptors for Tröger’s base1999In: Bioorganic Chemistry, Vol. 27, no 5, 363-371 p.Article in journal (Refereed)
  • 2.
    Andersson, Håkan S.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Figueredo, Sharel M.
    Haugaard-Kedström, Linda M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Bengtsson, Elina
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Daly, Norelle L.
    Qu, Xiaoqing
    Craik, David J.
    Ouellette, Andre J.
    Rosengren, K. Johan
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    The alpha-defensin salt-bridge induces backbone stability to facilitate folding and confer proteolytic resistance2012In: Amino Acids, ISSN 0939-4451, E-ISSN 1438-2199, Vol. 43, no 4, 1471-1483 p.Article in journal (Refereed)
    Abstract [en]

    Salt-bridge interactions between acidic and basic amino acids contribute to the structural stability of proteins and to protein-protein interactions. A conserved salt-bridge is a canonical feature of the alpha-defensin antimicrobial peptide family, but the role of this common structural element has not been fully elucidated. We have investigated mouse Paneth cell alpha-defensin cryptdin-4 (Crp4) and peptide variants with mutations at Arg(7) or Glu(15) residue positions to disrupt the salt-bridge and assess the consequences on Crp4 structure, function, and stability. NMR analyses showed that both (R7G)-Crp4 and (E15G)-Crp4 adopt native-like structures, evidence of fold plasticity that allows peptides to reshuffle side chains and stabilize the structure in the absence of the salt-bridge. In contrast, introduction of a large hydrophobic side chain at position 15, as in (E15L)-Crp4 cannot be accommodated in the context of the Crp4 primary structure. Regardless of which side of the salt-bridge was mutated, salt-bridge variants retained bactericidal peptide activity with differential microbicidal effects against certain bacterial cell targets, confirming that the salt-bridge does not determine bactericidal activity per se. The increased structural flexibility induced by salt-bridge disruption enhanced peptide sensitivity to proteolysis. Although sensitivity to proteolysis by MMP7 was unaffected by most Arg(7) and Glu(15) substitutions, every salt-bridge variant was degraded extensively by trypsin. Moreover, the salt-bridge facilitates adoption of the characteristic alpha-defensin fold as shown by the impaired in vitro refolding of (E15D)-proCrp4, the most conservative salt-bridge disrupting replacement. In Crp4, therefore, the canonical alpha-defensin salt-bridge facilitates adoption of the characteristic alpha-defensin fold, which decreases structural flexibility and confers resistance to degradation by proteinases.

  • 3.
    Andersson, Håkan S.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karlsson, Jesper G.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Piletsky, S A
    Koch-Schmidt, Ann-Christin
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Mosbach, K
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Influence of monomer-template ratio on selectivity and load capacity of molecularly imprinted polymers: indications of template self-association1999In: Journal of Chromatography A, Vol. 848, no 1-2, 39-49 p.Article in journal (Refereed)
  • 4.
    Andersson, Håkan S.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karlsson, Jesper G.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Svenson, Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Can template-template self-association contribute to polymer-ligand recognition characteristics?2000Conference paper (Refereed)
  • 5.
    Andersson, Håkan S.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Koch-Schmidt, Ann-Christin
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ohlson, Sten
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Study of the Nature of Recognition in Molecularly Imprinted Polymers1996In: J. Mol. Recogn., Vol. 9, p 675-682Article in journal (Refereed)
  • 6.
    Andersson, Håkan S.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Molecular Imprinting. Recent innovations in synthetic polymer receptor and enzyme mimics1997In: Recent Research Developments in Pure and Applied Chemistry, Vol. 1, 133-157 p.Article in journal (Refereed)
  • 7.
    Andersson, Håkan S.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Spectroscopic evaluation of molecular imprinting polymerization systems1997In: Bioorganic Chemistry, Vol. 25, 203-211 p.Article in journal (Refereed)
  • 8.
    Andersson, Håkan S.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    The development of molecular imprinting2000Other (Other academic)
  • 9.
    Andersson, Håkan S.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Piletsky, S A
    Mosbach, K
    Koch-Schmidt, Ann-Christin
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Novel recognition elements for improved molecularly imprinted polymer stereoselectivity1997Conference paper (Refereed)
  • 10.
    Andersson, Håkan S.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ramström, O
    Crown Ethers as a Tool for the Preparation of Molecularly Imprinted Polymers1998In: Journal of Molecular Recognition, Vol. 11, 103-106 p.Article in journal (Refereed)
  • 11.
    Andersson, Håkan S.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ramström, Olof
    Lund University.
    Crown ethers as a tool for the preparation of molecularly imprinted polymers1997Conference paper (Other academic)
  • 12. Andersson, L I
    et al.
    Nicholls, Ian Alan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Mosbach, K
    Immunoassays using molecularly imprinted polymers1995In: Immunoanalysis of agrochemicals: emerging technologies / [ed] Judd O. Nelson, Alexander E. Karu and Rosie B. Wong, American Chemical Society (ACS), 1995, 89-97 p.Conference paper (Other academic)
  • 13.
    Ankarloo, Jonas
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Wikman, Susanne
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Escherichia coli mar and acrAB Mutants Display No Tolerance to Simple Alcohols2010In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 11, no 4, 1403-1412 p.Article in journal (Refereed)
    Abstract [en]

    The inducible Mar phenotype of Escherichia coli is associated with increased tolerance to multiple hydrophobic antibiotics as well as some highly hydrophobic organic solvents such as cyclohexane, mediated mainly through the AcrAB/TolC efflux system. The influence of water miscible alcohols ethanol and 1-propanol on a Mar constitutive mutant and a mar deletion mutant of E. coli K-12, as well as the corresponding strains carrying the additional acrAB deletion, was investigated. In contrast to hydrophobic solvents, all strains were killed in exponential phase by 1-propanol and ethanol at rates comparable to the parent strain. Thus, the Mar phenotype does not protect E. coli from killing by these more polar solvents. Surprisingly, AcrAB does not contribute to an increased alcohol tolerance. In addition, sodium salicylate, at concentrations known to induce the mar operon, was unable to increase 1-propanol or ethanol tolerance. Rather, the toxicity of both solvents was increased in the presence of sodium salicylate. Collectively, the results imply that the resilience of E. coli to water miscible alcohols, in contrast to more hydrophobic solvents, does not depend upon the AcrAB/TolC efflux system, and suggests a lower limit for substrate molecular size and functionality. Implications for the application of microbiological systems in environments containing high contents of water miscible organic solvents, e. g., phage display screening, are discussed.

  • 14.
    Bergström, Maria
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Ganji, Suresh
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Naidu Veluru, Ramesh
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Unelius, C. Rikard
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    N-Iodosuccinimide (NIS) in Direct Aromatic Iodination2017In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 22, 3234-3239 p.Article in journal (Refereed)
    Abstract [en]

    N-Iodosuccinimide (NIS) in pure trifluoroacetic acid (TFA) offers a time-efficient and general method for the iodination of a wide range of mono-and disubstituted benzenes at room temperature, as demonstrated in this paper. The starting materials were generally converted into mono-iodinated products in less than 16 hours at room temperature, without byproducts. A few deactivated substrates needed addition of sulfuric acid to increase the reaction rate. Another exception was methoxybenzenes that preferentially were iodinated by NIS in acetonitrile with only catalytic amounts of TFA.

  • 15.
    Bohman, Björn
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Cavonius, Lillie
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unelius, C. Rikard
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Vegetables as biocatalysts in stereoselective hydrolysis of labile organic compounds2009In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 11, no 11, 1900-1905 p.Article in journal (Refereed)
    Abstract [en]

    Hydrolysis of labile esters of beta-hydroxyketones has been performed with whole plant tissue from various vegetables. The pheromone 5-hydroxy-4-methyl-3-heptanone (1) was used as the model compound. Hydrolysis of acetates and benzoates of 1 was unsuccessful using normal conditions of ester hydrolysis, both by chemical hydrolysis and by the means of commercial lipases. When, however, whole cells of carrot, celery root, eggplant, parsley root, parsnip and potato were used as reagents, hydrolysis of the acetates was successful. At low conversion the hydrolysis was stereoselective and at total conversion virtually no formation of by-products was observed. The selectivity varied among the eight vegetables that were evaluated. Methods of preparation and substrate-to-plant ratio were examined. Furthermore, acetates and benzoates of three analogous compounds [5-hydroxy-3-heptanone (2), 5-hydroxy-5-methyl-3-heptanone (3) and 5-ethyl-6-hydroxy-4-octanone (4)] were hydrolyzed by potato and sweet potato to various degrees, indicating that the method is general for the mild and stereoselective hydrolysis of secondary beta-alkoxy-and beta-aryloxyketones.

  • 16.
    Bohman, Björn
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Unelius, C. Rikard
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Synthesis of all four stereoisomers of 5-hydroxy-4-methyl-3-heptanone using plants and oyster mushrooms2009In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 65, no 42, 8697-8701 p.Article in journal (Refereed)
    Abstract [en]

    All four possible stereoisomers of 5-hydroxy-4-methyl-3-heptanone were synthesized from common achiral reagents using fast, straightforward organic synthesis, including the use of whole tissue of Daucus carota, Solanum melongena, and Pleurotus ostreatus.

  • 17. Cheshev, Pavel
    et al.
    Morelli, Laura
    Marchesi, Marco
    Podlipnik, Crtomir
    Bergström, Maria
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Bernardi, Anna
    Synthesis and affinity evaluation of a small library of bidentate cholera toxin ligands: towards nonhydrolyzable ganglioside mimics2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 6, 1951-1967 p.Article in journal (Refereed)
    Abstract [en]

    A small library of nonhydrolyzable mimics of GM1 ganglioside, featuring galactose and sialic acid its pharmacophoric carbohydrate residues,, was synthesized and tested. All compounds were synthesized from readily available precursors using high-performance reactions, including click chemistry protocols, and avoiding O-glycosidic bonds. Sonic of the most active molecules also feature a point of further derivatization that can be used for conjugation will, polyvalent aglycons. Their affinity towards cholera toxin was assessed by weak affinity chromatography, which allowed a systematic evaluation and selection of the best candidates. Affinity could be enhanced up to one or two orders of magnitude over the affinity of the individual pharmacophoric sugar residues.

  • 18.
    Elmlund, Louise
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Suriyanarayanan, Subramanian
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Wiklander, Jesper G.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Aastrup, Teodor
    Attana AB.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Uppsala University.
    Biotin selective polymer nano-films2014In: Journal of Nanobiotechnology, ISSN 1477-3155, E-ISSN 1477-3155, Vol. 12, 8Article in journal (Refereed)
    Abstract [en]

    Background: The interaction between biotin and avidin is utilized in a wide range of assay and diagnostic systems. A robust material capable of binding biotin should offer scope in the development of reusable assay materials and biosensor recognition elements. Results: Biotin-selective thin (3-5 nm) films have been fabricated on hexadecanethiol self assembled monolayer (SAM) coated Au/quartz resonators. The films were prepared based upon a molecular imprinting strategy where N, N'-methylenebisacrylamide and 2-acrylamido-2-methylpropanesulfonic acid were copolymerized and grafted to the SAM-coated surface in the presence of biotin methyl ester using photoinitiation with physisorbed benzophenone. The biotinyl moiety selectivity of the resonators efficiently differentiated biotinylated peptidic or carbohydrate structures from their native counterparts. Conclusions: Molecularly imprinted ultra thin films can be used for the selective recognition of biotinylated structures in a quartz crystal microbalance sensing platform. These films are stable for periods of at least a month. This strategy should prove of interest for use in other sensing and assay systems.

  • 19. El-Sayed, Ashraf
    et al.
    Manning, Lee-Anne
    Unelius, C. Rikard
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Park, Kye-Chung
    Stringer, Lloyd
    White, Nicola
    Bunn, Barry
    Twidle, Andrew
    Suckling, Max
    Attraction and Antennal Response of the Common Wasp, Vespula vulgaris (L.), to Selected Synthetic Chemicals in New Zealand Beech Forests2009In: Pest Management Science, ISSN 1526-498X, E-ISSN 1526-4998, Vol. 65, no 9, 975-981 p.Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The common wasp, Vespula vulgaris (L.), and the German wasp, Vespula germanica (F.), are significant problems in New Zealand beech forests (Nothofagus spp.), adversely affecting native birds and invertebrate biodiversity. This work was undertaken to develop synthetic attractants for these species to enable more efficient monitoring and management. RESULTS: Seven known wasp attractants (acetic acid, butyl butyrate, isobutanol, heptyl butyrate, octyl butyrate and 2,4-hexadienyl butyrate) were field tested, and only heptyl butyrate and octyl butyrate attracted significantly higher numbers of wasps than a non-baited trap. Accordingly, a series of straight-chain esters from methyl to decyl butyrate were prepared and field tested for attraction of social wasps. Peak biological activity occurred with hexyl butyrate, heptyl butyrate, octyl butyrate and nonyl butyrate. Polyethylene bags emitting approximately 18.4-22.6 mg day(-1) of heptyl butyrate were more attractive than polyethylene bags emitting approximately 14.7-16.8 mg day(-1) of heptyl butyrate in the field. Electroantennogram (EAG) studies indicated that queens and workers of V. vulgaris had olfactory receptor neurons responding to various aliphatic butyrates. CONCLUSION: These results are the first to be reported on the EAG response and the attraction of social wasps to synthetic chemicals in New Zealand beech forests and will enable monitoring of social wasp activity in beech forests. (C) 2009 Society of Chemical industry

  • 20.
    Friedman, Ran
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Ctr Biomat Chem.
    Structural and computational insights into the versatility of cadmium binding to proteins2014In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 43, no 7, 2878-2887 p.Article in journal (Refereed)
    Abstract [en]

    Cadmium is a highly toxic group XII metal, similar to zinc and mercury. Unlike zinc, which is one of the most common metal cofactors in biology, cadmium is highly toxic. Many Zn2+-binding proteins can bind Cd2+-ions without significantly affecting their structures. Here, the protein data bank is analysed with regard to protein-cadmium interactions, which shows that cadmium can bind to a variety of ion binding sites in proteins. Statistical analysis of Cd2+-side chain interactions is compared with a similar analysis of other ions. This analysis reveals that with regard to amino acid side-chain preference, Cd2+ is more similar to Mn2+ than to Zn2+ or Hg2+. Finally, the interaction energies of three native metal binding proteins are calculated where Cd2+ binds instead of Zn2+, Ca2+ or Cu2+. The interaction energies are decomposed into individual components whose contributions are discussed.

  • 21.
    Golker, Kerstin
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olsson, Gustaf D.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Towards Molecular Dynamics-Based Rational Design of Polymeric Recognition Systems2010Conference paper (Refereed)
    Abstract [en]

    Molecular imprinting is a technique used to design polymeric recognition materials with selectivity for a predetermined structure. The molecular imprinting process generates cavities in the polymer matrix that are complementary in size, shape and functionality to the template-structure. The recognition properties of molecularly imprinted polymers (MIPs) are comparable to those of antibodies and enzymes, which make MIPs utilizable in a wide range of application areas including biomimetic assays and biosensors [1]. Previous studies have shown that the prepolymerization step is central for the establishment of high affinity binding sites in MIPs [2]. However, our understanding of the physical mechanisms underlying MIP formation and template recognition is still limited. With the rapid increase of computational power and the development of suitable software molecular dynamics (MD) simulation methods have become a valuable theoretical tool to aid our understanding of the molecular imprinting process, and even in the development of rational design strategies [2]. Recently the first simulation of a complete prepolymerization mixture was presented [3].

    Here we present 10 ns MD simulations of a series of all-component prepolymerization mixtures. The simulated systems were assembled with different molar ratios using the local anaesthetic bupivacaine as the template, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, 2,2’-azobis-(2-methylpropionitrile) (AIBN) as the initiator and toluene as the solvent. The simulations were performed using the AMBER (v. 10.0 UCSF, San Francisco, CA) suite of programs (4) and the GAFF [6] force field. Molecular trajectories were evaluated with radial distribution functions and hydrogen bond analysis.

     

     

    References

    1. Alexander, C.; Andersson, H. S.; Andersson, L. I.; Ansell, R. J.; Kirsch, N.; Nicholls, I. A.; O´Mahony, J.; Whitcombe, J., J. Mol. Recognit. (2006), 19, 106-180
    2. Nicholls, I. A.; Andersson, H. S.; Charlton, C.; Henschel, H.; Karlsson, B. C. G.; Karlsson, J. G.; O´Mahony, J.; Rosengren, A. M.; Rosengren, K. J.; Wikman, S. Biosens. Bioelectron. (2009), 25, 543-552
    3. Karlsson, B. C. G.; O´Mahony, J.; Karlsson, J. G.; Bengtsson, H.; Eriksson, L. A.; Nicholls, I. A. J. Am. Chem. Soc. (2009), 131, 13297-13304
    4. Case, D. A.; Cheatham, T. E.; Darden, T.; Gohlke, H.; Luo, R.; Merz, K. M.; Onufriev, A.; Simmerling, C.; Wang, B.; Woods, R. J. Comput. Chem. (2009), 26, 1668-1688
    5. Wang, J.; Wolf, R. M.; Caldwell, J. W.; Kollman, P. A.; Case, D. A. J. Comput. Chem. (2004), 25, 1157-1174

     

  • 22.
    Golker, Kerstin
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olsson, Gustaf D.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Towards Molecular Dynamics-Based Rational Design of Synthetic Polymer Recognition Systems2010Conference paper (Refereed)
    Abstract [en]

    Molecularly imprinted polymers (MIPs) are polymeric receptors with selectivity for a predetermined structure. The molecular imprinting process generates cavities in a synthetic polymer matrix that are complementary in size, shape and functionality to the template. MIPs exhibit recognition properties analogous to their biological counterparts, such as antibodies, and can be utilized in a wide range of application areas [1]. Nonetheless, the physical mechanisms underlying MIP formation and template recognition are still poorly understood. Molecular dynamics (MD) based computer simulations are a valuable theoretical tool which may be used to aid our understanding of the molecular imprinting process, and even for the development of rational design strategies [2]. Recently the first MD simulation of a complete prepolymerization mixture was presented [3].

    In the present work, MD simulations of a series of all-component prepolymerization mixtures were performed, using the local anaesthetic bupivacaine as the template, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, 2,2’-azobis-(2-methylpropionitrile) (AIBN) as the initiator and toluene as the solvent. The simulated systems differed in the molar fraction of MAA. Systems were evaluated with radial distribution functions and hydrogen bond analyses. By correlating the results with the rebinding behaviour of a series of synthesized MIPs the importance of the stoichiometry between template, functional monomer and crosslinker was highlighted. The analysis of the MD simulations revealed strong competition for hydrogen bonding between the carbonyl oxygen’s of MAA and EGDMA and the amide proton of bupivacaine. Moreover, the hydrogen bonding contact between EGDMA and bupivacaine remained nearly unaffected by the varied molar fraction MAA in the different systems demonstrating the role of the crosslinker being more important as generally accepted.

     

    References

    [1]             Alexander, C.; Andersson, H. S.; Andersson, L. I.; Ansell, R. J.; Kirsch, N.; Nicholls, I. A.; O´Mahony, J.; Whitcombe, J., J. Mol. Recognit., 19, 106-180 (2006)

    [2]            Nicholls, I. A.; Andersson, H. S.; Charlton, C.; Henschel, H.; Karlsson, B. C. G.; Karlsson, J. G.; O´Mahony, J.; Rosengren, A. M.; Rosengren, K. J.; Wikman, S. Biosens. Bioelectron., 25, 543-552 (2009)

    [3]            Karlsson, B. C. G.; O´Mahony, J.; Karlsson, J. G.; Bengtsson, H.; Eriksson, L. A.; Nicholls, I. A. J. Am. Chem. Soc., 131, 13297-13304 (2009)

  • 23.
    Golker, Kerstin
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olsson, Gustaf D.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Towards the use of molecular dynamics as a predictive tool in the design of molecularly imprinted polymers2010Conference paper (Refereed)
    Abstract [en]

    Through the rapid increase in computational power and the development of suitable software, molecular dynamics (MD) has become a promising tool for use in the development of molecularly imprinted polymers (MIPs).1 MD is a computational method based on Newtonian mechanics, which enables the simultaneous simulation of thousands of discrete molecules, and can be used to establish the states of the molecular species present in MIP-prepolymerization mixtures. As detailed understanding of the molecular basis for formation of high affinity MIP sites is still lacking and the physical mechanism underlying specific recognition is still a matter of debate, the use of MD as a tool to investigate MIP-prepolymerization mixtures is highly motivated.1 Recently the first MD simulation of an all-component prepolymerization mixture was presented, which gave a detailed picture of the underlying monomer-template interactions important for the “molecular memory” in MIPs.2

    Here, we present results obtained from a series of MD simulations representing all-component MIP/REF prepolymerization mixtures assembled with differences in stoichiometries of functional and crosslinking monomer. In these mixtures, the local anaesthetic drug bupivacaine was used as a template, methacrylic acid as the functional monomer, ethylene dimethacrylate as crosslinking monomer, 2,2’-azobis-(2-methylpropionitrile) as the initiator and toluene as the solvent. Bupivacaine complexation in each system was evaluated with radial distribution functions and hydrogen bond analyses. By correlating the results with the rebinding behaviour of a series of synthesized bupivacaine-MIPs, the relationship between the degree of crosslinking and MIP-performance was highlighted.

    [1] Nicholls, I. A.; Andersson, H. S.; Charlton, C.; Henschel, H.; Karlsson, B. C. G.; Karlsson, J. G.; O´Mahony, J.; Rosengren, A. M.; Rosengren, K. J.; Wikman, S. Biosens. Bioelectron., 25, 543-552 (2009)

    [2] Karlsson, B. C. G.; O´Mahony, J.; Karlsson, J. G.; Bengtsson, H.; Eriksson, L. A.; Nicholls, I. A. J. Am. Chem. Soc., 131, 13297-13304 (2009)

  • 24.
    Golker, Kerstin
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Rosengren, Annika M.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Uppsala University.
    A Functional Monomer Is Not Enough: Principal Component Analysis of the Influence of Template Complexation in Pre-Polymerization Mixtures on Imprinted Polymer Recognition and Morphology2014In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 15, no 11, 20572-20584 p.Article in journal (Refereed)
    Abstract [en]

    In this report, principal component analysis (PCA) has been used to explore the influence of template complexation in the pre-polymerization phase on template molecularly imprinted polymer (MIP) recognition and polymer morphology. A series of 16 bupivacaine MIPs were studied. The ethylene glycol dimethacrylate (EGDMA)-crosslinked polymers had either methacrylic acid (MAA) or methyl methacrylate (MMA) as the functional monomer, and the stoichiometry between template, functional monomer and crosslinker was varied. The polymers were characterized using radioligand equilibrium binding experiments, gas sorption measurements, swelling studies and data extracted from molecular dynamics (MD) simulations of all-component pre-polymerization mixtures. The molar fraction of the functional monomer in the MAA-polymers contributed to describing both the binding, surface area and pore volume. Interestingly, weak positive correlations between the swelling behavior and the rebinding characteristics of the MAA-MIPs were exposed. Polymers prepared with MMA as a functional monomer and a polymer prepared with only EGDMA were found to share the same characteristics, such as poor rebinding capacities, as well as similar surface area and pore volume, independent of the molar fraction MMA used in synthesis. The use of PCA for interpreting relationships between MD-derived descriptions of events in the pre-polymerization mixture, recognition properties and morphologies of the corresponding polymers illustrates the potential of PCA as a tool for better understanding these complex materials and for their rational design.

  • 25.
    Guo, Ming
    et al.
    Zhejiang Agr & Forestry Univ, Peoples R China.
    Wang, Xiaomeng
    Zhejiang Agr & Forestry Univ, Peoples R China.
    Lu, Xiaowang
    Zhejiang Agr & Forestry Univ, Peoples R China.
    Wang, Hongzheng
    Zhejiang Agr & Forestry Univ, Peoples R China.
    Brodelius, Peter E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    alpha-Mangostin Extraction from the Native Mangosteen (Garcinia mangostana L.) and the Binding Mechanisms of alpha-Mangostin to HSA or TRF2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 9, e0161566Article in journal (Refereed)
    Abstract [en]

    In order to obtain the biological active compound, alpha-mangostin, from the traditional native mangosteen (Garcinia mangostana L.), an extraction method for industrial application was explored. A high yield of a-mangostin (5.2%) was obtained by extraction from dried mangosteen pericarps with subsequent purification on macroporous resin HPD-400. The chemical structure of alpha-mangostin was verified mass spectrometry (MS), nuclear magnetic resonance (H-1 NMR and C-13 NMR), infrared spectroscopy (IR) and UV-Vis spectroscopy. The purity of the obtained alpha-mangostin was 95.6% as determined by HPLC analysis. The binding of native alpha-mangostin to human serum albumin (HSA) or transferrin (TRF) was explored by combining spectral experiments with molecular modeling. The results showed that amangostin binds to HSA or TRF as static complexes but the binding affinities were different in different systems. The binding constants and thermodynamic parameters were measured by fluorescence spectroscopy and absorbance spectra. The association constant of HSA or TRF binding to alpha-mangostin is 6.4832x10(5) L/mol and 1.4652x10(5) L/mol at 298 K and 7.8619x10(5) L/mol and 1.1582x10(5) L/mol at 310 K, respectively. The binding distance, the energy transfer efficiency between alpha-mangostin and HSA or TRF were also obtained by virtue of the Forster theory of non-radiation energy transfer. The effect of alpha-mangostin on the HSA or TRF conformation was analyzed by synchronous spectrometry and fluorescence polarization studies. Molecular docking results reveal that the main interaction between amangostin and HSA is hydrophobic interactions, while the main interaction between alpha-mangostin and TRF is hydrogen bonding and Van der Waals forces. These results are consistent with spectral results.

  • 26. Göransson, Ulf
    et al.
    Herrmann, Anders
    Burman, Robert
    Haugaard-Kedström (published under the name Haugaard-Jönsson), Linda M.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Rosengren, K. Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    The conserved Glu in the cyclotide cycloviolacin O2 has a key structural role2009In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 10, no 14, 2354-2360 p.Article in journal (Refereed)
    Abstract [en]

    Cyclotides are a large family of plant peptides that are characterised by a head-to-tail circular backbone and three disulfide bonds that are arranged in a cystine knot. This unique structural feature, which is referred to as a cyclic cystine knot, gives the cyclotides remarkable stability against chemical and biological degradation. In addition to their natural function as insecticides for plant defence, the cyclotides have a range of bioactivities with pharmaceutical relevance, including cytotoxicity against cancer cell lines. A glutamic acid residue, aside from the invariable disulfide array, is the most conserved feature throughout the cyclotide family, and it has recently been shown to be crucial for biological activity. Here we have used solution-state NMR spectroscopy to determine the three-dimensional structures of the potent cytotoxic cyclotide cycloviolacin O2, and an inactive analogue in which this conserved glutamic acid has been methylated. The structures of the peptides show that the glutamic acid has a key structural role in coordinating a set of hydrogen bonds in native cycloviolacin O2; this interaction is disrupted in the methylated analogue. The proposed mechanism of action of cyclotides is membrane disruption and these results suggest that the glutamic acid is linked to cyclotide function by stabilising the structure to allow efficient aggregation in membranes, rather than in a direct interaction with a target receptor.

  • 27.
    Haugaard-Kedström, Linda M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Structure and function of relaxins2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The relaxin/insulin superfamily is a group of peptide hormones that consists of ten members in human, namely relaxins 1-3, insulin-like peptides (INSL) 3-6, insulin and insulin-like growth factors (IGF) I-II. These peptides have various functions in the body, such as regulating growth, blood glucose levels,  collagen metabolism, germ cell maturation and appetite. Misregulation of these mechanisms is associated with disease and accordingly they are of interest as potential pharmaceutical targets. Structurally the hormones are characterised by two peptide chains, A and B, which are held together by one intra A-chain and two inter chain disulfide bonds. Four different G-protein coupled receptors (GPCR) called relaxin family peptide receptor (RXFP) 1-4 have been found to respond to stimuli by different relaxin peptides. RXFP3 and RXFP4 are classic peptide ligand GPCRs, whereas RXFP1 and RXFP2 are characterised by a large extracellular leucine rich-repeat domain. Relaxin-3, which is the relaxin family ancestor, is the only relaxin peptide known to be able to bind and activate both subtypes of GPCRs, namely RXFP1, RXFP3 and RXFP4.

    The aim of this thesis was to analyse the structure-function relationship of the relaxin ligands and receptors, and to use this information to develop selective ligands for the relaxin receptors, which can be used as drug leads or pharmacological tools for investigating the physiological roles of the RXFPs.

    The 3D structures of native INSL5 and relaxin-2 were determined by solution NMR spectroscopy. The peptides showed an insulin/relaxin-like overall fold. A relaxin chimera peptide, consisting of the A-chain from INSL5 and the B-chain from relaxin-3, R3/I5, which has been shown to be selective for RXFP3 and RXFP4 over RXFP1, was also subjected to NMR studies. The R3/I5 peptide maintained an insulin/relaxin-like overall fold, and the relaxin-3 B-chain adopted a conformation identical to that in native relaxin-3, confirming that the activity of R3/I5 can be directly related to its primary sequence. Furthermore, a truncation study was undertaken to ascertain the importance of the termini for structure and function. By using the knowledge generated from the structure-function relationship, a single-chain high affinity RXFP3 selective antagonist was developed.

    In conclusion, this thesis has contributed to broaden the knowledge of the structure-function relationship of the relaxin ligands and the development of a selective RXFP3 antagonist, which is currently a drug lead for treatment of neurological disorders including stress and obesity.

  • 28.
    Haugaard-Kedström (published under the name Haugaard-Jönsson), Linda M.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hossain, Akther
    Daly, Norelle
    Bathgate, Ross
    Craik, David
    Wade, John
    Rosengren, Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Structural characterization of a H3-INSL5 relaxin peptide chimera2007In: Proceedings of the 4th International Peptide Symposium / [ed] Wilce, Jackie, Cairns, Australia, 2007Conference paper (Refereed)
  • 29.
    Haugaard-Kedström (published under the name Haugaard-Jönsson), Linda M.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hossain, M. Akhter
    Daly, Norelle L.
    Bathgate, Ross A.D.
    Wade, John D.
    Craik, David J.
    Rosengren, K. Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Structural Properties of Relaxin Chimeras: NMR Characterization of the R3/I5 Relaxin Peptide2009In: Annals of the New York Academy of Sciences, ISSN 0077-8923, E-ISSN 1749-6632, Vol. 1160, 27-30 p.Article in journal (Refereed)
    Abstract [en]

    Relaxin-3 interacts with high potency with three relaxin family peptide receptors (RXFP1, RXFP3, and RXFP4). Therefore, the development of selective agonist and antagonist analogs is important for in vivo studies characterizing the biological significance of the different receptor-ligand systems and for future pharmaceutical applications. Recent reports demonstrated that a peptide selective for RXFP3 and RXFP4 over RXFP1 can be generated by the combination of the relaxin-3 B chain with the A chain from insulin-like peptide 5 (INSL5), creating an R3/I5 chimera. We have used NMR spectroscopy to determine the three-dimensional structure of this peptide to gain structural insights into the consequences of combining chains from two different relaxins. The R3/I5 structure reveals a similar backbone conformation for the relaxin-3 B chain compared to native relaxin-3, and the INSL5 A chain displays a relaxin/insulin-like fold with two parallel helices. The findings indicate that binding and activation of RXFP3 and RXFP4 mainly require the B chain and that the A chain functions as structural support. RXFP1, however, demonstrates a more complex binding mechanism, involving both the A chain and the B chain. The creation of chimeras is a promising strategy for generating new structure-activity data on relaxins.

  • 30.
    Haugaard-Kedström (published under the name Haugaard-Jönsson), Linda M.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hossain, M. Akhter
    Daly, Norelle L.
    Craik, David J.
    Wade, John D.
    Rosengren, K. Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Structure of the human insulin-like peptide 5 and characterization of conserved hydrogen bonds and electrostatic interactions within the relaxin framework2009In: Biochemical Journal, ISSN 0264-6021, E-ISSN 1470-8728, Vol. 419, 619-627 p.Article in journal (Refereed)
    Abstract [en]

    INSL5 (insulin-like peptide 5) is a two-chain peptide hormone related to insulin and relaxin. It was recently discovered through searches of expressed sequence tag databases and, although the fulfil biological significance of INSL5 is still being elucidated, high expression in peripheral tissues such as the colon, as well as in the brain and hypothalamus, suggests roles in gut contractility and neuroendocrine signalling. INSL5 activates the relaxin family peptide receptor 4 with high potency and appears to be the endogenous ligand for this receptor, on the basis of overlapping expression profiles and their apparent co-evolution. In the present Study, we have used solution-state NMR to characterize the three-dimensional structure of synthetic human INSL5. The structure reveals an insulin/relaxin-like fold with three helical segments that are braced by three disulfide bonds and enclose a hydrophobic core. Furthermore, we characterized in detail the hydrogen-bond network and electrostatic interactions between charged groups in INSL5 by NMR-monitored temperature and pH titrations and Undertook a comprehensive structural comparison with other members of the relaxin family, thus identifying the conserved structural features of the relaxin fold. The B-chain helix, which is the primary receptor-binding site of the relaxins, is longer in INSL5 than in its close relative relaxin-3. As this feature results in a different positioning of the receptor-activation domain Arg(B23) and Trp(B24), it may be an important contributor to the difference in biological activity observed for these two peptides. Overall, the structural Studies provide mechanistic insights into the receptor selectivity of this important family of hormones. 

  • 31.
    Haugaard-Kedström (published under the name Haugaard-Jönsson), Linda M.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hossain, Mohammed Akhter
    Daly, Norelle L.
    Bathgate, Ross A.D.
    Wade, John D.
    Craik, David J.
    Rosengren, Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Structure of the R3/I5 chimeric relaxin peptide, a selective GPCR135 and GPCR142 agonist2008In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 283, no 35, 23811-23818 p.Article in journal (Refereed)
    Abstract [en]

    The human relaxin family comprises seven peptide hormones with various biological functions mediated through interactions with G-protein-coupled receptors. Interestingly, among the hitherto characterized receptors there is no absolute selectivity toward their primary ligand. The most striking example of this is the relaxin family ancestor, relaxin-3, which is an agonist for three of the four currently known relaxin receptors: GPCR135, GPCR142, and LGR7. Relaxin-3 and its endogenous receptor GPCR135 are both expressed predominantly in the brain and have been linked to regulation of stress and feeding. However, to fully understand the role of relaxin-3 in neurological signaling, the development of selective GPCR135 agonists and antagonists for in vivo studies is crucial. Recent reports have demonstrated that such selective ligands can be achieved by making chimeric peptides comprising the relaxin-3 B-chain combined with the INSL5 A-chain. To obtain structural insights into the consequences of combining A-and B-chains from different relaxins we have determined the NMR solution structure of a human relaxin-3/INSL5 chimeric peptide. The structure reveals that the INSL5 A-chain adopts a conformation similar to the relaxin-3 A-chain, and thus has the ability to structurally support a native-like conformation of the relaxin-3 B-chain. These findings suggest that the decrease in activity at the LGR7 receptor seen for this peptide is a result of the removal of a secondary LGR7 binding site present in the relaxin-3 A-chain, rather than conformational changes in the primary B-chain receptor binding site. 

  • 32.
    Henschel, Henning
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosengren, Annika M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Insights into the Isomerisation Mechanism of Warfarin2010Conference paper (Refereed)
    Abstract [en]

    Warfarin is one of the most commonly used drugs in anticoagulent therapy. Notwithstanding its wide use, achieving correct dosage is often a major challenge due to its narrow therapeutic window.[1] The bioavailability of warfarin is believed to be greatly influenced by the environment-dependent composition of the ensemble of isomers present. While the different structures of warfarin have been discussed in earlier publications,[2] details of the mechanism underlying the formation of the cyclic hemiacetal (Figure 1) had not yet been investigated.

    Figure 1. Cyclization reaction of warfarin.

    Figure 2. Transition state in presence of one water molecule.

     

    We have now studied the reaction by means of density functional calculations. Comparison of results from calculations performed on the isolated warfarin molecule and in presence of water molecules (compare Figure 2) highlight the importance of intermolecular interactions in the key proton transfer step for the reaction to proceed. A viable model for the mechanism underlying the isomerisation shall be presented.

     

     

    References

    [1]             J. Ansell, J. Hirsh, L. Poller, H. Bussey, A. Jacobsen and E. Hylek, Chest, 126, 204S (2004).

    [2]            B. C. G. Karlsson, A. M. Rosengren, P. O. Andersson and I. A. Nicholls, J. Phys. Chem. B, 111,10520 (2007).

  • 33.
    Henschel, Henning
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karlsson, Björn C. G.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosengren, Annika M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    The Mechanistic Basis for Warfarin’s Structural Diversity and Implications for Its Bioavailability2010In: Journal of Molecular Structure: THEOCHEM, ISSN 0166-1280, Vol. 958, 7-9 p.Article in journal (Refereed)
    Abstract [en]

    The anticoagulent drug warfarin exhibits chameleon-like isomerism, where the environment-dependent composition of the ensemble of structures greatly influences its bioavailability. Here, the mechanism of conversion between the major isomeric forms is studied. The dramatic differences in transition state energies, as determined by density functional calculations, highlight the necessity for the involvement of intermolecular interactions in the key proton transfer step. A viable model for the mechanism underlying the isomerization reactions is presented.

  • 34.
    Henschel, Henning
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Prosenc, Marc H.
    University of Hamburg, Germany.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. Uppsala University.
    A Density Functional Study on the Factors Governing Metal Catalysis of the Direct Aldol Reaction2011In: Journal of Molecular Catalysis A: Chemical, ISSN 1381-1169, E-ISSN 1873-314X, Vol. 351, 76-80 p.Article in journal (Refereed)
    Abstract [en]

    Density functional calculations are employed in the study of the C-C bond formation step of an aldol reaction in presence of a series of metals. Focus was placed on first row d-block metals that have been used in catalysis of direct aldol reactions. The obtained energy profiles are analysed in order to differentiate between factors governing catalysis. Results demonstrate a major influence of d-orbital occupation, and suggest some of the so far less commonly used metals as promising candidates for development of new catalytic systems.

  • 35. Hossain, M. Akhter
    et al.
    Bathgate, Ross A.D.
    Kong, Chze K.R.
    Shabanpoor, Fazel
    Zhang, Suode
    Haugaard-Kedström (published under the name Haugaard-Jönsson), Linda M.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Rosengren, Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Tregear, Geoffrey W.
    Wade, John D.
    Synthesis, conformation, and activity of human insulin-like peptide 5 (INSL5)2008In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 9, no 11, 1816-1822 p.Article in journal (Refereed)
    Abstract [en]

    Insulin-like peptide 5 (INSL5) was first identified through searches of the expressed sequence tags (EST) databases. Primary sequence analysis showed it to be a prepropeptide that was predicted to be processed in vivo to yield a two-chain sequence (A and B) that contained the insulin-like disulfide cross-links. The high affinity interaction between INSL5 and the receptor RXFP4 (GPCR142) coupled with their apparent coevolution and partially overlapping tissue expression patterns strongly suggest that INSL5 is an endogenous ligand for RXFP4. Given that the primary function of the INSL5–RXFP4 pair remains unknown, an effective means of producing sufficient quantities of this peptide and its analogues is needed to systematically investigate its structural and biological properties. A combination of solid-phase peptide synthesis methods together with regioselective disulfide bond formation were used to obtain INSL5. Both chains were unusually resistant to standard synthesis protocols and required highly optimized conditions for their acquisition. In particular, the use of a strong tertiary amidine, DBU, as Nα-deprotection base was required for the successful assembly of the B chain; this highlights the need to consider incomplete deprotection rather than acylation as a cause of failed synthesis. Following sequential disulfide bond formation and chain combination, the resulting synthetic INSL5, which was obtained in good overall yield, was shown to possess a similar secondary structure to human relaxin-3 (H3 relaxin). The peptide was able to inhibit cAMP activity in SK-N-MC cells that expressed the human RXFP4 receptor with a similar activity to H3 relaxin. In contrast, it had no activity on the human RXFP3 receptor. Synthetic INSL5 demonstrates equivalent activity to the recombinant-derived peptide, and will be an important tool for the determination of its biological function.

  • 36. Hossain, M. Akhter
    et al.
    Bathgate, Ross A.D.
    Rosengren, K. Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Shabanpoor, Fazel
    Zhang, Suode
    Lin, Feng
    Tregear, Geoffrey W.
    Wade, John D.
    The structural and functional role of the B-chain C-terminal arginine in the relaxin-3 peptide antagonist, R3(B Delta 23-27)R/I5.2009In: Chemical Biology and Drug Design, ISSN 1747-0277, E-ISSN 1747-0285, Vol. 73, no 1, 46-52 p.Article in journal (Refereed)
    Abstract [en]

    Relaxin-3, a member of the insulin superfamily, is involved in regulating stress and feeding behavior. It is highly expressed in the brain and is the endogenous ligand for the receptor RXFP3. As relaxin-3 also interacts with the relaxin receptor RXFP1, selective agonists and antagonists are crucial for studying the physiological function(s) of the relaxin-3/RXFP3 pair. The analog R3(B Delta 23-27)R/I5, in which a C-terminally truncated human relaxin-3 (H3) B-chain is combined with the INSL5 A-chain, is a potent selective RXFP3 antagonist and has an Arg residue remaining on the B-chain C-terminus as a consequence of the recombinant protein production process. To investigate the role of this residue in the RXFP3 receptor binding and activation, the analogs R3(B Delta 23-27)R/I5 and R3(B Delta 23-27)R containing the B-chain C-terminal Arg as well as R3(B Delta 23-27)/I5 and R3(B Delta 23-27), both lacking the Arg, were chemically assembled and their secondary structure and receptor activity assessed. The peptides generally had a similar conformation but those with the extra Arg residue displayed a significantly increased affinity for the RXFP3. Interestingly, in contrast to R3(B Delta 23-27)R and R3(B Delta 23-27)R/I5, the peptide R3(B Delta 23-27) is a weak agonist. This suggests that the C-terminal Arg, although increasing the affinity, alters the manner in which the peptide binds to the receptor and thereby prevents activation, giving R3(B Delta 23-27)R/I5 its potent antagonistic activity.

  • 37. Hossain, M. Akhter
    et al.
    Rosengren, Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Haugaard-Kedström (published under the name Haugaard-Jönsson), Linda M.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Zhang, Suode
    Layfield, Sharon
    Ferraro, Tania
    Daly, Norelle L.
    Tregear, Geoffrey W.
    Wade, John D.
    Bathgate, Ross A.D.
    The A-chain of the human relaxin family peptides has distinct roles in the binding and activation of the different relaxin family peptide receptors2008In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 283, no 25, 17287-17297 p.Article in journal (Refereed)
    Abstract [en]

    The relaxin peptides are a family of hormones that share a structural fold characterized by two chains, A and B, that are cross-braced by three disulfide bonds. Relaxins signal through two different classes of G-protein-coupled receptors (GPCRs), leucine-rich repeat-containing GPCRs LGR7 and LGR8 together with GPCR135 and GPCR142, now referred to as the relaxin family peptide (RXFP) receptors 1-4, respectively. Although key binding residues have been identified in the B-chain of the relaxin peptides, the role of the A-chain in their activity is currently unknown. A recent study showed that INSL3 can be truncated at the N terminus of its A-chain by up to 9 residues without affecting the binding affinity to its receptor RXFP2 while becoming a high affinity antagonist. This suggests that the N terminus of the INSL3 A-chain contains residues essential for RXFP2 activation. In this study, we have synthesized A-chain truncated human relaxin-2 and -3 (H2 and H3) relaxin peptides, characterized their structure by both CD and NMR spectroscopy, and tested their binding and cAMP activities on RXFP1, RXFP2, and RXFP3. In stark contrast to INSL3, A-chain-truncated H2 relaxin peptides lost RXFP1 and RXFP2 binding affinity and concurrently cAMP-stimulatory activity. H3 relaxin A-chain-truncated peptides displayed similar properties on RXFP1, highlighting a similar binding mechanism for H2 and H3 relaxin. In contrast, A-chain-truncated H3 relaxin peptides showed identical activity on RXFP3, highlighting that the B-chain is the sole determinant of the H3 relaxin-RXFP3 interaction. Our results provide new insights into the action of relaxins and demonstrate that the role of the A-chain for relaxin activity is both peptide- and receptor-dependent. 

  • 38. Hossain, M. Akhter
    et al.
    Rosengren, K. Johan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Zhang, Suode
    Bathgate, Ross A.D.
    Tregear, Geoffrey W.
    van Lierop, Bianca J.
    Robinson, Andrea J.
    Wade, John D.
    Solid phase synthesis and structural analysis of novel A-chain dicarba analogs of human relaxin-3 (INSL7) that exhibit full biological activity2009In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 7, no 8, 1547-1553 p.Article in journal (Refereed)
    Abstract [en]

    Replacement of disulfide bonds with non-reducible isosteres can be a useful means of increasing the in vivo stability of a protein. We describe the replacement of the A-chain intramolecular disulfide bond of human relaxin-3 (H3 relaxin, INSL7), an insulin-like peptide that has potential applications in the treatment of stress and obesity, with the physiologically stable dicarba bond. Solid phase peptide synthesis was used to prepare an A-chain analogue in which the two cysteine residues that form the intramolecular bond were replaced with allylglycine. On-resin microwave-mediated ring closing metathesis was then employed to generate the dicarba bridge. Subsequent cleavage of the peptide from the solid support, purification of two isomers and their combination with the B-chain via two intermolecular disulfide bonds, then furnished two isomers of dicarba-H3 relaxin. These were characterized by CD spectroscopy, which suggested a structural similarity to the native peptide. Additional analysis by solution NMR spectroscopy also identified the likely cis/trans form of the analogs. Both peptides demonstrated binding affinities that were equivalent to native H3 relaxin on RXFP1 and RXFP3 expressing cells. However, although the cAMP activity of the analogs on RXFP3 expressing cells was similar to the native peptide, the potency on RXFP1 expressing cells was slightly lower. The data confirmed the use of a dicarba bond as a useful isosteric replacement of the disulfide bond.

  • 39.
    Hulteberg, Christian
    et al.
    Biofuel-Solution i Malmö AB ( Lund University/ Chemical Engineering) .
    Brandin, Jan
    Linnaeus University, Faculty of Science and Engineering, School of Engineering. Biofuel-Solution i Malmö AB.
    Method for Hydrogenating 1,2-Unsaturated Carbonylic Compounds2011Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Disclosed is a method of hydrogenating an1,2-unsaturated carbonylic compound to obtain the corresponding saturated carbonylic compound in the presence of a palladium catalyst with heterogeneous distribution of palladium

  • 40.
    Hulteberg, Christian
    et al.
    Lund University.
    Leveau, Andreas
    Biofuel-Solution AB, Limhamn.
    Brandin, Jan
    Biofuel-Solution AB, Limhamn.
    Pore Condensation i Glycerol Dehydration2013In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 56, no 9-10, 813-821 p.Article in journal (Refereed)
    Abstract [en]

    Pore condensation followed by polymerizationis proposed as an explanatory model of several observationsreported in the literature regarding the dehydration ofglycerol to acrolein. The major conclusion is that glycerolpore condensation in the micro- and mesopores, followedby polymerization in the pores, play a role in catalystdeactivation.

  • 41.
    Karlsson, Björn C. G.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Olsson, Gustaf D.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosengren, Annika M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    The Effect of Warfarin’s Structural Diversity on Permeation Across a DPPC Bilayer Membrane2010Conference paper (Refereed)
    Abstract [en]

    Warfarin is an oral anticoagulant drug used to prevent thrombolic disorders such as myocardial infarction and stroke by inhibiting the active site of vitamin-K dependent epoxide reductase (VKOR) [1]. Despite being in widespread use and having a narrow therapeutic window, its mechanisms of action are not yet fully understood and incorrect warfarin dosage often leads to severe side effects. A factor limiting our understanding of warfarin’s bioavailability is warfarin’s structural diversity, which has been shown to be strongly affected by the nature of molecular environment e.g. solvent polarity and pH [2-7]. One of the major factors contributing to a drug’s biological effect is membrane transport, a process involving exposure of warfarin to environments of quite different character. Since a drug’s transport across membrane may include both active transport by carriers as well as diffusion-controlled processes, it may be envisaged that in order to fully predict warfarin’s anticoagulant effect these mechanisms must be carefully elucidated.

     

    Molecular dynamics (MD) simulations have previously been performed in order to obtain detailed information on static equilibrium as well as dynamic properties of small organic drugs in biomembranes. One of the most studied lipids in cell membrane simulations has been dipalmitoylphosphatidylcholine (DPPC) which is the most abundant phospholipid in cell membranes. Here we present lipid bilayer membrane transport properties for a series of warfarin structures previously reported in the literature using a fully solvated DPPC membrane model. Data extracted from simulations shed light on differences in membrane partioning as well as mobilities of warfarin isomers studied and a mechanism by which warfarin permeates through membranes in vivo is presented.

     

    References

    1. Landefeld, C.; Beyth, R. Am. J. Med. 1993, 95, 315-328.
    2. Karlsson, B. C. G.; Rosengren, A. M.; Andersson, P. O.; Nicholls, I. A. J. Phys. Chem. B 2007, 111, 10520-10528.
    3. Karlsson, B. C. G.; Rosengren, A. M.; Andersson, P. O.; Nicholls, I. A. J. Phys. Chem. B 2009, 113, 7945-7949.
    4. Karlsson, B. C. G.; Rosengren, A. M.; Näslund, I.; Andersson, P. O.; Nicholls, I. A. Submitted 2010.
    5. Rosengren, A. M.; Karlsson, B. C. G.; Näslund, I.; Andersson, P. O.; Nicholls, I. A. Submitted 2010.
    6. Nicholls, I. A.; Karlsson, B. C. G.; Rosengren, A. M.; Henschel, H. J. Mol. Recognit. 2010, In press.
    7. Henschel, H.; Karlsson, B. C. G.; Rosengren, A. M.; Nicholls, I. A. Submitted 2010.

     

  • 42.
    Karlsson, Björn C. G.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    O'Mahony, John
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karlsson, Jesper G.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bengtsson, Helen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Eriksson, Leif A
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Structure and Dynamics of Monomer-Template Complexation: An Explanation for Molecularly Imprinted Polymer Recognition Site Heterogeneity2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 37, 13297-13304 p.Article in journal (Refereed)
    Abstract [en]

    We here present the first simulation of a complete molecularly imprinted polymer prepolymerization system. Molecular dynamics studies were performed for a system comprising a total of 1199 discrete molecules, replicating the components and concentrations employed in the corresponding polymer synthesis. The observed interactions correlate well with results obtained from (1)H NMR spectroscopic studies. Comparison with simulations performed in the absence of cross-linking agent (ethylene dimethacrylate) demonstrated its significance in the formation of ligand recognition sites. Moreover, the influence of events such as template-template (bupivacaine) and monomer-monomer (methacrylic acid) self-association, porogen-template interactions, and template conformational variability was revealed. The template recognition capacity of the modeled polymer system was verified by synthesis of imprinted and reference polymers and subsequent radioligand binding Analysis. Collectively, through a series of statistical analyses of molecular trajectories in conjunction with spectroscopic data it was demonstrated that an ensemble of complex structures is present in the prepolymerization mixture and that this diversity is the basis for the binding site heterogeneity observed in molecularly imprinted polymers (MIPs) prepared using the noncovalent strategy.

  • 43.
    Karlsson, Björn C. G.
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Rosengren, Annika M.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Andersson, Per Ola
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Molecular Insights on the Two Fluorescence Lifetimes Displayed by Warfarin from Fluorescence Anisotropy and Molecular Dynamics Studies2009In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 113, no 22, 7945-7949 p.Article in journal (Refereed)
    Abstract [en]

    A series of steady-state fluorescence anisotropy experiments has been performed to demonstrate the presence of a deprotonated open side chain form of warfarin in organic environments. We explain the observed emission-wavelength-dependent anisotropy of warfarin in ethanol, 2-propanol, and acetonitrile due to the coexistence of neutral isomers and deprotonated open side chain forms displaying different fluorescence decay kinetics. To investigate solvent-solute interactions in more detail, a series of molecular dynamics simulations was performed to study warfarin solvation and to predict the time scale of rotational diffusion displayed by this compound. Predictions obtained provide an explanation for the nonzero values in anisotropy observed for neutral isomers of warfarin associated with the short fluorescence lifetime (tau < 0.1 ns) and for an approximately zero anisotropy observed for the deprotonated open side chain form, which is associated with the longer fluorescence lifetime (tau = 0.5-1.6 ns). Finally, we address the potential use of fluorescence anisotropy for an increased understanding of the structural diversity of warfarin in protein binding pockets.

  • 44.
    Karlsson, Björn C. G.
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Rosengren, Annika M.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Näslund, Inga
    FOI, Swedish Defence Research Agency.
    Andersson, Per Ola
    FOI, Swedish Defence Research Agency.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    A molecularly imprinted polymer-based detection of Warfarin using time resolved fluorescence spectroscopy2010Conference paper (Refereed)
    Abstract [en]

    Warfarin is a clinically important drug widely used in the treatment of thrombolic disorders e.g. myocardial infarction and stroke.1 When administered, 99% of the drug present in blood is bound to the transport protein human serum albumin (HSA).2 On account of the fact that HSA demonstrates polymorphism and warfarin has a narrow therapeutic index, careful monitoring of the effect of drug-dosage must be performed.

    Currently, warfarin’s anticoagulant effect is measured by an indirect method in which the clotting time is measured and correlated to the amount of warfarin present. As current methods for self-monitoring are limited, the development of alternative robust and more sensitive methods is desirable.

    In this study, we have developed a non-covalent molecularly imprinted polymer3 (MIP) system with selectivity for warfarin.4 The HSA-like binding properties of this MIP were established in previous efforts to develop polymers capable of HSA-like binding of warfarin.5

    In principle, the fluorophoric nature of warfarin should allow for the fluorescence spectroscopy-based detection of the drug. Recent efforts by us,6-8 using a series of theoretical and spectroscopic studies have highlighted the complex nature of warfarin. In particular, the medium dependent isomerization of this drug illustrates why spectroscopy based methods for the direct detection of the drug has not been forthcoming. Results from these studies have been used to develop a method for the in situ detection of warfarin using time resolved fluorescence spectroscopy.

    (1)      Landefeld, C.; Beyth, R. Anticoagulant-related bleeding - epidemiology, prediction and prevention. Am. J. Med. 1993, 95, 315-328.

    (2)      Yacobi, A.; Udall, J. A.; Levy, G. Comparative pharmacokinetics of coumarin anticoagulants.18 Serum-protein binding as a determinant of warfarin body clearance and anticoagulant effect. Clin. Pharmacol Ther. 1976, 19, 552-558.

    (3)      Alexander, C.; Andersson, H. S.; Andersson, L. I.; Ansell, R. J.; Kirsch, N.; Nicholls, I. A.; O'Mahony, J.; Whitcombe, M. J. Molecular imprinting science and technology: A survey of the literature for the years up to and including 2003. Journal of Molecular Recognition 2006, 19, 106-180.

    (4)      Rosengren, A. M.; Karlsson, B. C. G.; Näslund, I.; Andersson, P. O.; Nicholls, I. A. Time resolved fluorescence spectroscopic detection of the anticoagulant warfarin: A sensor-based method for direct detection in blood plasma. 2010, Submitted.

    (5)      Karlsson, B. C. G.; Rosengren, A. M.; Näslund, I.; Andersson, P. O.; Nicholls, I. A. Synthetic Human Serum Albumin Sudlow I binding site mimics. 2010, Submitted.

    (6)      Karlsson, B. C. G.; Rosengren, A. M.; Andersson, P. O.; Nicholls, I. A. The Spectrophysics of Warfarin: Implications for Protein Binding J. Phys. Chem. B 2007, 111, 10520-10528.

    (7)      Karlsson, B. C. G.; Rosengren, A. M.; Andersson, P. O.; Nicholls, I. A. Molecular Insights on the Two Fluorescence Lifetimes Displayed by Warfarin from Fluorescence Anisotropy and Molecular Dynamics Studies. J. Phys. Chem. B 2009, 113, 7945-7949.

    (8)      Nicholls, I. A.; Karlsson, B. C. G., Rosengren, A. M.. Henschel, H. Warfarin: an Environment-Dependent Switchable Molecular Probe. J. Mol. Recognit. 2010, in press.

  • 45.
    Karlsson, Björn
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    O'Mahony, John
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Karlsson, Jesper G
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bengtsson, Helen
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Eriksson, Leif A
    Nicholls, Ian Alan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Structure and dynamics of monomer-template complexation: an explanation for molecularly imprinted polymer recognition site heterogeneity2008Conference paper (Other academic)
  • 46.
    Kathiravan, Subban
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Uppsala university.
    Palladium Catalyzed Vinyltrifluoromethylation of Aryl Halides through Decarboxylative Cross-Coupling with 2-(Trifluoromethyl)acrylic Acid2015In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 17, 1874-1877 p.Article in journal (Refereed)
    Abstract [en]

    An efficient Pd-catalyzed stereoselective vinyltrifluoromethylation of aryl halides, through decarboxylative cross-coupling with 2-(trifluoromethyl)acrylic acid is described. The ready availability of the starting materials, the high level of functional group tolerance, and excellentE/Z selectivity make this protocol a safe and operationally convenient strategy for efficient synthesis of vinyltrifluoromethyl derivatives.

  • 47.
    Kathiravan, Subban
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Uppsala University.
    Rhodium-Catalyzed Oxidative Perfluoroalkenylation by Carbonyl Group Directed C-H Bond Activation2014In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 32, 7211-7219 p.Article in journal (Refereed)
    Abstract [en]

    The selective activation of C-H bonds under mild Rh-III catalytic conditions has been developed for the perfluoroalkenylation of various cyclic and acyclic aromatic ketones. This protocol uses versatile reagents and mild conditions. It requires a very low catalyst loading and has exceptional functional group tolerance as well as provides products in good to excellent yields. An application of this approach was described for the preparation of perfluoroethyl acrylate derivatives of biologically active substances.

  • 48.
    Kathiravan, Subban
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Uppsala University.
    Rhodium(III)-catalysed aerobic synthesis of highly functionalized indoles from N-arylurea under mild conditions through C-H activation2014In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 50, no 95, 14964-14967 p.Article in journal (Refereed)
    Abstract [en]

    A Rh(III) catalysed amino arylation of alkynes using copper as the terminal oxidant for regeneration of the catalytically active species under aerobic conditions is described. This novel C-H activation reaction was applied to the synthesis of a wide range of substituted indoles from N-arylureas.

  • 49.
    Kathiravan, Suppan
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Nicholls, Ian A.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Uppsala University.
    Cobalt Catalyzed, Regioselective C(sp(2))-H Activation of Amides with 1,3-Diynes2017In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 19, no 18, 4758-4761 p.Article in journal (Refereed)
    Abstract [en]

    The development of a first row transition metal (cobalt)-based catalyst for the as yet unexplored CH activation-driven reaction of 1,3-diynes, themselves a functional class of interest in a range of application areas, to form isoquinolinonesan important structural motif in a number of biologically active substancesis presented. This versatile and inexpensive catalyst employs a covalently attached bidendate-directing group, 8-aminoquinoline. The template directs the CH activation and facilitates the synthesis of a wide range of alkynylated heterocycles under mild conditions and with excellent regioselectivity. This strategy provides a novel and efficient route to diverse heterocyclic frameworks as demonstrated by its late stage application in bisheterocycle syntheses.

  • 50.
    Kirsch, Nicole
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hedin-Dahlström, Jimmy
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Henschel, Henning
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Whitcombe, Michael J
    Wikman, Susanne
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Nicholls, Ian A.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Molecularly imprinted polymer catalysis of a Diels-Alder reaction2009In: Journal of Molecular Catalysis B: Enzymatic, ISSN 1381-1177, E-ISSN 1873-3158, Vol. 58, no 1-4, 110-117 p.Article in journal (Refereed)
    Abstract [en]

    A series of synthetic polymers were designed and synthesized for enhancing the rate of the Diels-Alder cycloaddition reaction of 1,3-butadiene carbamic acid benzyl ester (11) and N,N-dimethyl acrylamide (2), to yield the corresponding endo- (3) and exo- (4) reaction products. Putative transition state analogues (TSAs) for the endo- (5) and exo- (6) reaction pathways were used as templates for the synthesis of molecularly imprinted methacrylic acid (MAA)-divinylbenzene (DVB) copolymers. The polymer system utilized was selected based upon a series of (1)H NMR studies of complex formation between template and a functional monomer analogue (K(d) (app) approximate to 70 mM, d(8)-toluene, 293 K). Batch binding studies revealed that the imprinted polymers were selective for the TSA corresponding to the template used in the polymer synthesis. Studies on the influence of the polymers on the catalysis of the reaction of 1 and 2 demonstrated a 20-fold enhancement of the rate of the reaction relative to the solution reaction. A surprising temperature dependence of the reaction of 1 and 2 in the presence of the polymers was observed, which provides support for the role of template-functional monomer complexes in the catalysis of the Diels-Alder reaction.

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