In this paper, three different methods were used to study the binding numbe
rs and binding constants of chrome-azurol S (CAS) on bovine serum albumin (
BSA), and almost same results were obtained. It is proposed that the concen
tration of CAS and pH of the solutions affect the binding mode of CAS and B
SA. According to the theory of Forster non-radiative energy transfer, the b
inding sites of CAS on BSA are found. Taking advantage of fluorescence quen
ching, the reaction mechanism of CAS and BSA is explored.