title: Characterizing Active Pharmaceutical Ingredient Binding to Human Serum Albumin by Spin-Labeling and EPR Spectroscopy.
abstract: Drug binding to human serum albumin (HSA) has been characterized by a spin-labeling and continuous-wave (CW) EPR spectroscopic approach. Specifically, the contribution of functional groups (FGs) in a compound on its albumin-binding capabilities is quantitatively described. Molecules from different drug classes are labeled with EPR-active nitroxide radicals (spin-labeled pharmaceuticals (SLPs)) and in a screening approach CW-EPR spectroscopy is used to investigate HSA binding under physiological conditions and at varying ratios of SLP to protein. Spectral simulations of the CW-EPR spectra allow extraction of association constants (KA ) and the maximum number (n) of binding sites per protein. By comparison of data from 23 SLPs, the mechanisms of drug-protein association and the impact of chemical modifications at individual positions on drug uptake can be rationalized. Furthermore, new drug modifications with predictable protein binding tendency may be envisaged.
authors.affiliation: Martin-Luther-Universität Halle-Wittenberg, Institute of Chemistry, Von-Danckelmann-Platz 4, 06120, Halle (Saale), Germany.
authors.forename: Till
authors.initials: T
authors.lastname: Hauenschild
authors.affiliation: Martin-Luther-Universität Halle-Wittenberg, Institute of Chemistry, Von-Danckelmann-Platz 4, 06120, Halle (Saale), Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Reichenwallner
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Enkelmann
authors.affiliation: Martin-Luther-Universität Halle-Wittenberg, Institute of Chemistry, Von-Danckelmann-Platz 4, 06120, Halle (Saale), Germany. dariush.hinderberger@chemie.uni-halle.de.
authors.forename: Dariush
authors.identifier: http://orcid.org/0000-0002-6066-7099
authors.initials: D
authors.lastname: Hinderberger
mesh_terms: D001665:Binding Sites; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D006801:Humans; D009589:Nitrogen Oxides / Q000737:chemistry*; D011485:Protein Binding; D000075462:Serum Albumin, Human / Q000737:chemistry* / Q000378:metabolism; D013113:Spin Labels
chemical_list: D009589:Nitrogen Oxides; D013113:Spin Labels; C039900:nitroxyl; D000075462:Serum Albumin, Human
keywords: EPR spectroscopy; binding properties; drug delivery; spin-labeling; structure-activity relationships