The TcO4- binding to human serum albumin

The stoichiometry and the characteristics of the TcO4- binding equilibrium to human serum albumin were investigated with the use of 99TcO4-. Based on the Scatchard plots, the number of binding sites and the association constants were obtained at pH 7.38, 6.04, 5.10, 4.18, 2.80 and 0.65, respectively. From the parameters at pH 7.38, it was estimated that 64% of TcO4- added was bound to human serum albumin under physiological condition. Variance in the values at pH 7.38, 6.04 and 5.10 shows that these bindings are stabilized by electrostatic forces. Below pH 4.18 the number of binding sites increased and the association constants diminished. These phenomena may be attributed to the conformation change of human serum albumin. (auth.)