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  • 1.
    Duong-Thi, Minh-Dao
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Introducing weak affinity chromatography to drug discovery with focus on fragment screening2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fragment-based drug discovery is an emerging process that has gained popularity in recent years. The process starts from small molecules called fragments. One major step in fragment-based drug discovery is fragment screening, which is a strategy to screen libraries of small molecules to find hits. The strategy in theory is more efficient than traditional high-throughput screening that works with larger molecules. As fragments intrinsically possess weak affinity to a target, detection techniques of high sensitivity to affinity are required for fragment screening. Furthermore, the use of different screening methods is necessary to improve the likelihood of success in finding suitable fragments. Since no single method can work for all types of screening, there is a demand for new techniques. The aim of this thesis is to introduce weak affinity chromatography (WAC) as a novel technique for fragment screening.

    WAC is, as the name suggests, an affinity-based liquid chromatographic technique that separates compounds based on their different weak affinities to an immobilized target. The higher affinity a compound has towards the target, the longer it remains in the separation unit, and this will be expressed as a longer retention time. The affinity measure and ranking of affinity can be achieved by processing the obtained retention times of analyzed compounds.

    In this thesis, WAC is studied for fragment screening on two platforms. The first system comprised a 24-channel affinity cartridge that works in cooperation with an eight-needle autosampler and 24 parallel UV detector units. The second system was a standard analytical LC-MS platform that is connected to an affinity column, generally called WAC-MS or affinity LC-MS. The evaluation criteria in studying WAC for fragment screening using these platforms were throughput, affinity determination and ranking, specificity, operational platform characteristics and consumption of target protein and sample. The model target proteins were bovine serum albumin for the first platform, thrombin and trypsin for the latter. Screened fragments were either small molecule drugs, a thrombin-directed collection of compounds, or a general-purpose fragment library. To evaluate WAC for early stages of fragment elaboration, diastereomeric mixtures from a thrombin-directed synthesis project were screened.

    Although both analytical platforms can be used for fragment screening, WAC-MS shows more useful features due to easy access to the screening platform, higher throughput and ability to analyze mixtures. Affinity data from WAC are in good correlation with IC50 values from enzyme assay experiments. The possibility to distinguish specific from non- specific interactions plays an important role in the interpretation of WAC results. In this thesis, this was achieved by inhibiting the active site of the target protein to measure off-site interactions. WAC proves to be a sensitive, robust, moderate in cost and easy to access technique for fragment screening, and can also be useful in the early stages of fragment evolution.

    In conclusion, this thesis has demonstrated the proof of principle of using WAC as a new tool to monitor affinity and to select hits in fragment-based drug discovery. This thesis has indicated the primary possibilities, advantages as well as the limitations of WAC in fragment screening procedures.  In the future, WAC should be evaluated on other targets and fragment libraries in order to realize more fully the potential of the technology.

  • 2.
    Duong-Thi, Minh-Dao
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Bergström, Gunnar
    Linköping Univ, Sweden.
    Mandenius, Carl-Fredrik
    Linköping Univ, Sweden.
    Bergström, Maria
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Fex, Tomas
    Univ Gothenburg, Sweden.
    Ohlson, Sten
    Nanyang Technol Univ, Singapore.
    Comparison of weak affinity chromatography and surface plasmon resonance in determining affinity of small molecules2014In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 461, p. 57-59Article in journal (Refereed)
    Abstract [en]

    In this study, we compared affinity data from surface plasmon resonance (SPR) and weak affinity chromatography (WAC), two established techniques for determination of weak affinity (mM-mu M) small molecule-protein interactions. In the current comparison, thrombin was used as target protein. In WAC the affinity constant (K-D) was determined from retention times, and in SPR it was determined by Langmuir isotherm fitting of steady-state responses. Results indicate a strong correlation between the two methods (R-2 = 0.995, P < 0.0001). (C) 2014 Elsevier Inc. All rights reserved.

  • 3.
    Duong-Thi, Minh-Dao
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences. Nanyang Technol University, Singapore.
    Bergström, Maria
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Edwards, Katarina
    Uppsala University.
    Eriksson, Jonny
    Uppsala University.
    Ohlson, Sten
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    To Yiu Ying, Janet
    Nanyang Technol University, Singapore.
    Torres, Jaume
    Nanyang Technol University, Singapore.
    Agmo Hernández, Víctor
    Uppsala University.
    Lipodisks integrated with weak affinity chromatography enable fragment screening of integral membrane proteins2016In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 141, no 3, p. 981-988Article in journal (Refereed)
    Abstract [en]

    Membrane proteins constitute the largest class of drug targets but they present many challenges in drug discovery. Importantly, the discovery of potential drug candidates is hampered by the limited availability of efficient methods for screening drug-protein interactions. In this work we present a novel strategy for rapid identification of molecules capable of binding to a selected membrane protein. An integral membrane protein (human aquaporin-1) was incorporated into planar lipid bilayer disks (lipodisks), which were subsequently covalently coupled to porous derivatized silica and packed into HPLC columns. The obtained affinity columns were used in a typical protocol for fragment screening by weak affinity chromatography (WAC), in which one hit was identified out of a 200 compound collection. The lipodisk-based strategy, which ensures a stable and native-like lipid environment for the protein, is expected to work also with other membrane proteins and screening procedures.

  • 4.
    Duong-Thi, Minh-Dao
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Bergström, Maria
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Fex, Tomas
    Astra& Zeneca R&D Mölndal, Mölndal, Sweden.
    Isaksson, Roland
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Ohlson, Sten
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    High-Throughput Fragment Screening by Affinity LC-MS2013In: Journal of Biomolecular Screening, ISSN 1087-0571, E-ISSN 1552-454X, Vol. 18, no 2, p. 160-171Article in journal (Refereed)
    Abstract [en]

    Fragment screening, an emerging approach for hit finding in drug discovery, has recently been proven effective by its first approved drug, vemurafenib, for cancer treatment. Techniques such as nuclear magnetic resonance, surface plasmon resonance, and isothemal titration calorimetry, with their own pros and cons, have been employed for screening fragment libraries. As an alternative approach, screening based on high-performance liquid chromatography separation has been developed. In this work, we present weak affinity LC/MS as a method to screen fragments under high-throughput conditions. Affinity-based capillary columns with immobilized thrombin were used to screen a collection of 590 compounds from a fragment library. The collection was divided into 11 mixtures (each containing 35 to 65 fragments) and screened by MS detection. The primary screening was performed in < 4 h (corresponding to > 3500 fragments per day). Thirty hits were defined, which subsequently entered a secondary screening using an active site-blocked thrombin column for confirmation of specificity. One hit showed selective binding to thrombin with an estimated dissociation constant (K-D) in the 0.1 mM range. This study shows that affinity LC/MS is characterized by high throughput, ease of operation, and low consumption of target and fragments, and therefore it promises to be a valuable method for fragment screening.

  • 5.
    Duong-Thi, Minh-Dao
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Bergström, Maria
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Fex, Tomas
    Astra&Zeneca R&D, Sweden.
    Svensson, Susanne
    Chalmers University of Technology, Sweden.
    Ohlson, Sten
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Isaksson, Roland
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Weak Affinity Chromatography for Evaluation of Stereoisomers in Early Drug Discovery2013In: Journal of Biomolecular Screening, ISSN 1087-0571, E-ISSN 1552-454X, Vol. 18, no 6, p. 748-755Article in journal (Refereed)
    Abstract [en]

    In early drug discovery (e.g. in fragment screening), recognition of stereoisomeric structures is valuable and guides medicinal chemists to focus only on useful configurations. In this work, we concurrently screened mixtures of stereoisomers and estimated their affinities to a protein target (thrombin) using weak affinity chromatography-mass spectrometry (WAC-MS). Affinity determinations by WAC showed that minor changes in stereoisomeric configuration could have major impact on affinity. The ability of WAC-MS to provide instant information about stereoselectivity and binding affinities directly from analyte mixtures is a great advantage in fragment library screening and drug lead development.

  • 6.
    Duong-Thi, Minh-Dao
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Meiby, Elinor
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Bergström, Maria
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Fex, Tomas
    Isaksson, Roland
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Ohlson, Sten
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Weak affinity chromatography as a new approach for fragment screening in drug discovery2011In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 414, no 1, p. 138-146Article in journal (Refereed)
    Abstract [en]

    Fragment-based drug design (FBDD) is currently being implemented in drug discovery, creating a demand for developing efficient techniques for fragment screening. Due to the intrinsic weak or transient binding of fragments (mM–uM in dissociation constant (KD)) to targets, methods must be sensitive enough to accurately detect and quantify an interaction. This study presents weak affinity chromatography (WAC) as an alternative tool for screening of small fragments. The technology was demonstrated by screening of a selected 23 compound fragment collection of documented binders, mostly amidines, using trypsin and thrombin as model target protease proteins. WAC was proven to be a sensitive, robust, and reproducible technique that also provides information about affinity of a fragment in the range of 1 mM–10uM. Furthermore, it has potential for high throughput as was evidenced by analyzing mixtures in the range of 10 substances by WAC–MS. The accessibility and flexibility of the technology were shown as fragment screening can be performed on standard HPLC equipment. The technology can further be miniaturized and adapted to the requirements of affinity ranges of the fragment library. All these features of WAC make it a potential method in drug discovery for fragment screening.

  • 7.
    Ohlson, Sten
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Duong-Thi, Minh-Dao
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Bergström, Maria
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Fex, Tomas
    Hansson, Lennart
    Pedersen, Lennart
    Guazotti, Sergio
    Isaksson, Roland
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Toward high-throughput drug screening on a chip-based parallell affinity separation platform2010In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 33, no 17-18, p. 2575-2581Article in journal (Refereed)
    Abstract [en]

    High-throughput screening of compound libraries, including the study of fragments, has become one of the cornerstones in modern drug discovery research. During this process hits are defined that may be developed into valuable leads and eventually into possible drug candidates. In this paper, we have demonstrated that parallel zonal weak affinity chromatography in microcolumns on a chip offers a possible screening format for weakly binding ligands toward a protein target. We used albumin as a model system because this transport protein is well established as a binder (both weak and strong) for drug substances. Bovine serum albumin was immobilized on microparticulate diolsilica particles and then packed into a 24-channel cartridge, which served as the separation platform. Analysis of the obtained chromatograms yielded information about affinity even in the millimolar range. Employing this approach, thousands of substances can be screened in just a day. We feel confident that zonal affinity chromatography will provide a useful technology in the future for performing high-throughput screening.

  • 8.
    Ohlson, Sten
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Duong-Thi, Minh-Dao
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Meiby, Elinor
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Isaksson, Roland
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Fex, Tomas
    Methods using weak interaction chromatography to separate and determine affinities of stereoisomers2012Patent (Other (popular science, discussion, etc.))
1 - 8 of 8
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