BINDING OF COUMARINS TO SITE-I OF HUMAN SERUM-ALBUMIN - EFFECT OF THEFATTY-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 repr esented by warfarin binding and the specific binding region represente d by azapropazone and phenylbutazone binding. In this paper binding pa rameters to defatted HSA and to HSA with fatty acids (molar ratio of f atty acid/HSA = 4) were compared. High-affinity binding sites for warf arin, 4-chromanol, 4-hydroxycoumarin, coumarin, 3-acetylcoumarin and p henylbutazone (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 cap acity of warfarin to HSA (2 > n > 1).