EQUILIBRIUM DIALYSIS STUDY ON THE INTERACTION BETWEEN CU(II) AND HSA OR BSA

The interaction of Cu(II) and human serum albumin (HSA) or bovine seru m albumin (BSA) at physiological pH is studied by equilibrium dialysis . The successive stability constants are obtained by non-linear least square methods fitting Bjerrum formula. For both the Cu(II)-HSA and Cu (II)-BSA systems, the order of magnitude of K-1 and K-2 was found to b e approximate to 10(4) mol(-1) dm(3). There are about twenty stoichiom etry binding sites found in one HSA or BSA molecule. They can be divid ed into two or three sets. Results of equilibrium dialysis experiments suggest that there exists one strong metal binding site in both Cu(II )-HSA and Cu(II)-BSA. It is the imidazol group nitrogen atoms of His(3 ) that are primarily concerned with copper binding site. After reachin g dialysis equilibrium, there is the interaction among the different b inding sites, the values of K all deviate from the simple statistical effect except for K-1 and K-2 in both Cu(II)-HSA and Cu(II)-BSA system s, and the positive cooperative effect is found.