Structural Studies on Metal-Serum Albumin III . Slow Conformational Transition of HSA and BSA Induced by Ni~(2+) Ion

Abstract

A notable hysteretic effect has been observed in the interaction of Ni2+ ion with human or bovine serum albumin using UV - Visible spectrometry, which shows that the binding of Ni2+ ion can induce a slow transition of HSA and BSA from the conformation of weaker affinity for Ni2+ ion to the one of stronger affinity (T - R transition). This conformational transition is supported by the time -dependence of the optical rotation of the samples. The rate constants and activation parameters of these transitions have been measured and discussed. It is inferred that such a conformational transition may mainly occur in the IA subdomain of the proteins,and is likely to be a hinged movement, which makes the IA subdomain become more open.