BINDING OF COUMARINS TO SITE-I OF HUMAN SERUM-ALBUMIN - EFFECT OF THE FATTY-ACIDS

It is known that binding site I on human serum albumin (HSA) consists of a zone of two overlapping regions: the specific binding region represented by warfarin binding and the specific binding region represented by azapropazone and phenylbutazone binding. In this paper binding parameters to defatted HSA and to HSA with fatty acids (molar ratio of fatty acid/HSA = 4) were compared. High-affinity binding sites for warfarin, 4-chromanol, 4-hydroxycoumarin, coumarin, 3-acetylcoumarin and phenylbutazone (759 549 M(-1) > K-a > 67 024 M(-1)) constitute binding site I on HSA. In this binding area defatted HS can bind two molecules of warfarin, but the presence of fatty acids diminish the binding capacity of warfarin to HSA (2 > n > 1).