DETERMINATION OF BINDING CONFORMATIONS OF DRUGS TO HUMAN SERUM-ALBUMIN BY TRANSFERRED NUCLEAR OVERHAUSER EFFECT MEASUREMENTS AND CONFORMATIONAL-ANALYSES USING HIGH-TEMPERATURE MOLECULAR-DYNAMICS CALCULATIONS

The binding conformations of oxyphenbutazone (OXY), N-epsilon-dansyl-L -lysine (DNS-LYS), and furosemide (FU) to human serum albumin (HSA) ha ve been investigated by molecular dynamics (MD) calculations and trans ferred nuclear Overhauser effect (TRNOE) measurements. We have combine d distance information obtained from the Conformational Analyzer with Molecular Dynamics And Sampling (CAMDAS) calculation and experimental NOE spectroscopy measurements to determine a ''binding conformation'' for each drug which binds to site I of HSA. For OXY, only one conforme r (conf9) among the conformer set generated by MD calculation satisfie d the distance restraint conditions obtained from TRNOE measurements. For DNS-LYS and FU, 17 and 5 conformers satisfied distance restraint c onditions, respectively. The structure of conf9 of OXY was taken as a ''template'' to choose binding conformers for DNS-LYS and FU. By fitti ng the ''template'' to the 17 conformers of DNS-LYS and 5 conformers o f FU, we could efficiently obtain one binding conformer for DNS-LYS (c onf144) and FU (conf26). It is suggested from the feature of the bindi ng conformation that the three-dimensional location of a hydrophobic a romatic ring, alkyl chain, and electronegative functional group is imp ortant for binding to site I of HSA. This method, which combines MD ca lculations and NOE information, is thought to be effective for determi ning the binding conformation of drugs to HSA.