Study on the Interaction between Vincristine and Bovine Serum Albumin

The interaction between vincristine(VCR) and bovine serum albumin(BSA) was investigated by UV-Vis absorption,fluorescence and circular dichroism(CD) spectra at 296,303 and 310 K,respectively.With fluorescence quenching method,the binding constants Ka were determined to be 1.5×104 L·mol-1,9.5×103 L·mol-1,4.9×103 L·mol-1 and the number of binding site was 1 at three temperatures,respectively.The conformation of BSA was altered(CD data) with the reductions of α-helices from 33.5% for free BSA to 29.7%,and with increases of β-sheet from 13.6% for free BSA to 18.4% in the presence of VCR.The thermodynamic parameters,enthalpy change(ΔH) and entropy change(ΔS),were calculated to be-62.07 kJ·mol-1 and-129.38 J·(mol·K)-1 respectively,according to van′t Hoff equation,which indicated that hydrogen bonds and van der walls interactions played major roles in the binding process.