Objective: The interaction of zidovudine and zidovudine acetate ester (AZT-Es)

with bovine serum albumin(BSA) has been investigated under physiological conditions. The binding constants

binding sites

binding type and effect of coexisting ions on the binding were studied. Method: The interaction of AZT and AZT-Es

with bovine serum albumin(BSA) has been studied by fluorescence quenching

synchronous fluorescence spectroscopy and ultraviolet spectrophotometry at different temperatures. The Stern-Volmer formula was used to process the experiment date. The binding constant and number of binding sites were obtained. Result: The interaction of AZT with BSA is mainly static quenching at temperature range of 289-310 K

while interaction of AZT-Es with BSA is dominate by the static quenching at lower temperature

and turned to be combination of static and dynamic quenching at higher temperature. The binding is mainly driven by the hydrophobic interaction for both two systems and they bound at a molar ratio of 1:1. The synchronous spectra showed that with increasing AZT-Es contents

the conformations of BSA tyrosyl and tryptophan residues were changed

and the hydrophobicity of the environment around the residues were decreased. The effects of coexisting metal ions on the binding constants of two systems are negligible. Conclusion: The interaction of AZT and AZT-Es with BSA are different quenching mechanism at different temperature. The binding is mainly driven by the hydrophobic interaction for both two systems. The effects of coexisting metal ions on the binding constants of two systems are negligible.