The interaction of 3-[di(carboxymethyl)aminomethyl]-1, 2- dihydroxyanthraquinone (AFB) and bovine serum albumin (BSA) was investigated by spectrophotometric method in acidic solution (pH4.1). When BSA was added into AFB solution, a purple color was observed, which indicated formation the of the AFB-BSA complex. The maximum absorption of the complex was obtained at 510nm, with the apparent molar absorptivity of ε=1.2474×10^4mol^-^1.cm^-^1.L. Two conditional constants were defined: the maximum binding number n=7 and apparent binding constant K~c=3.85×10^6. It is suggested that the electrostatic force is the main binding force. The Scatchard model is appropriate in the treatment of data obtained here. It is found that sodium chloride concentration of the solution has significant effect on the sensitivity of AFB-BSA complex.

Key words: ANTHRAQUINONE P, PROTEIN, SERUM ALBUMIN, ULTRAVIOLET SPECTROPHOTOMETRY, INTERACTIONS