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Electrospray ionization mass spectrometry as a tool for determination of drug binding sites to human serum albumin by noncovalent interaction

Authors

  • Kurt Benkestock,

    Corresponding author
    1. Biovitrum AB, Department of Structural Chemistry, SE-112 76, Stockholm, Sweden
    2. Royal Institute of Technology, Department of Analytical Chemistry, SE-100 44, Stockholm, Sweden
    Current affiliation:
    1. Medivir AB, Department of Analytical Chemistry, SE-141 44 Huddinge, Sweden.
    • Medivir AB, Department of Analytical Chemistry, SE-141 44 Huddinge, Sweden.
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  • Per-Olof Edlund,

    1. Biovitrum AB, Department of Analytical Sciences, SE-112 76, Stockholm, Sweden
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  • Johan Roeraade

    1. Royal Institute of Technology, Department of Analytical Chemistry, SE-100 44, Stockholm, Sweden
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Abstract

Most proteins in blood plasma bind ligands. Human serum albumin (HSA) is the main transport protein with a very high capacity for binding of endogenous and exogenous compounds in plasma. Many pharmacokinetic properties of a drug depend on the level of binding to plasma proteins. This work reports studies of noncovalent interactions by means of nanoelectrospray ionization mass spectrometry (nanoESI-MS) for determination of the specific binding of selected drug candidates to HSA. Warfarin, iopanoic acid and digitoxin were chosen as site-specific probes that bind to the main sites of HSA. Two drug candidates and two known binders to HSA were analyzed using a competitive approach. The drugs were incubated with the target protein followed by addition of site-specific probes, one at a time. The drug candidates showed predominant affinity to site I (warfarin site). Naproxen and glyburide showed affinity to both sites I and II. The advantages of nanoESI-MS for these studies are the sensitivity, the absence of labeled molecules and the short method development time. Copyright © 2005 John Wiley & Sons, Ltd.

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