Interactions between Orange II and Components in Heat-Treated Bovine Serum Albumin

Abstract

In the earlier date, interactions between dyes and heat-treated bovine serum albumin (BSA) were studied using the whole solutions of heat-treated BSA themselves. Since it is known that heat-treated BSA consists of several components, interactions between dye and some of the individual components isolated from heat-treated solution of BSA are to be studied.By use of the native BSA monomer, components (1') and (2), spectrophotometric measurements were made at pH 7.O and 25°C on systems of Orange II and these albumin species. Components (1') and (2) were isolated from BSA solution heat-treated at pH 9 and 65°C for 60 min. Spectrophotometric data were analyzed by Terada-Miyake's method [Kolloid Z. Z. Polym., 251, 139 (1973)] to determine binding parameters. For the native BSA monomer, n (number of binding sites on the protein for the dye) was 6.4 and K (equilibrium constant of the system) was O.92 × 105 M-1. For components (1') and (2), values of n and K were different from those of the native BSA monomer.