Interaction of N′‐(1‐Carboxyethylidene)salicylhydrazide with Bovine Serum Albumin

Abstract

Abstract Under the simulated physiological condition of an animal body, the interaction between N′‐(1‐carboxyethylidene)salicylhydrazide (CESH) and bovine serum albumin (BSA) was investigated by fluorescence spectra, UV‐Vis absorption spectra and circular dichroism (CD) spectra. The experiment results showed that the fluorescence of BSA was strongly quenched by CESH because of the formation of a CESH‐BSA complex, indicating a static quenching mechanism in the binding process. The modified Stern‐Volmer quenching constants (Ka) were 11.23×104, 7.103×104, 4.934×104 and 2.495×104 L·mol−1 at 292, 298, 304 and 310 K, respectively. The thermodynamic parameters ΔG, ΔH and ΔS at the four temperatures were calculated according to van't Hoff equation and the results indicated that hydrogen bonds and van der Waals force played major roles in stabilizing the CESH‐BSA complex. The distance r=4.26 nm between the donor BSA and acceptor CESH was obtained according to F?rster's non‐radiative energy transfer theory. The synchronous fluorescence spectral results indicated that the hydrophobicity of tyrosine residue increased while the microenvironment around tryptophan residue had no change. The CD and three‐dimensional fluorescence spectral results showed that in the presence of CESH, the α‐helix content of BSA decreased and the microenvironment and conformation of BSA changed.