Abstract

INTERACTIO OF CEFMINOX WITH BOVINE SERUM ALBUMINXuyang Liu, Ming Su, Peiyun Chen, Hanwen Sun*

Xuyang Liu, Ming Su, Peiyun Chen, Hanwen Sun*

ABSTRACT

The interaction of cefminox with bovine serum albumin (BSA) was studied by fluorescence quenching in combination with UV -Vis spectroscopic method under near physiological conditions. The fluorescence quenching rate constants and binding constants for BSA–cefminox system were determined at different temperatures. The fluorescence quenching of BSA by cefminox is due to static quenching and energy transfer. The results of thermodynamic parameters, ΔH (–96.19 kJ mol–1), ΔS (–226.26 J mol–1K–1) and ΔG (–28.7 to –25.4 kJ mol–1), indicated that van der Waals interaction and hydrogen bonding played a major role for cefminox–BSA association. The competitive experiments demonstrated that the primary binding site of cefminox within subdomain IIIA and the second binding site within subdomain IIA of BSA. The distance between BSA and cefminox is estimated to be 1.09 nm based on the Förster resonance energy transfer theory. The binding constant (Ka) of BSA–cefminox was 1.49×105L mol–1. Circular dichroism spectra, synchronous fluorescence and threedimensional fluorescence studies showed that the presence of cefminox could slightly change the conformation of BSA during the binding process.

Keywords: The interaction of cefminox with bovine serum albumin (BSA) was studied by fluorescence quenching in combination with UV -Vis spectroscopic method under near physiological conditions. The fluorescence quenching rate constants and binding constants for BSA