Equilibrium dialysis of metal-serum albumin (II) - Allosteric effect in Ni(II)-serum albumin systems

Abstract

Detailed studies were carried out on equilibrium dialysis of the binding of Ni 2+ ion to human serum albumin (HSA) and bovine serum albumin (BSA). The successive stability constants were obtained by the least-squares fitting. The eight binding sites found for both Ni(II)-HSA and Ni(II)-BSA systems can be divided into two different sets; and for both systems, there exist two identical prior binding sites where the bound Ni 2+ ions can be considered as allosteric effectors, which induce the allosteric effect in accordance with the model proposed by Monod et al. As indicated by allosteric parameters, the ability of R-state to bind Ni 2+ ions is ca. 100 times as much as that of T-state, and the conformation of HSA is markedly tenser than that of BSA.