The interaction of tylophorinidine,a potential leukemic drug,with bovine serum albumin

Association of tylophorinidine with bovine serum albumin was indioated by the quenching of the protein fluorescence above pH 7.0. The association constant, Ka, at pH 9.2 was calculated to be 5 × 10⁴ litres/mole. The Ka increased with increasing temperature, and the change in enthalpy, ΔH, was calculated to be 4.5 Kcals. The stoichionetry of binding obtained from Job's plot was 1:1. The data suggest involvement of tryptophan and hydrophobic forces in the albumintylophorinidine complex.