Temperature, pH and additives effects on the binding of Caffeic acid phenethyl ester to the native state of bovine serum albumin

Abstract

Caffeic acid phenethyl ester (CAPE, phenethyl 3-(3,4-dihydroxyphenyl)acrylate), an important anti-tumor components of Beehive Propolis, has many pharmacological activities. The interaction of CAPE with bovine serum albumin (BSA) was thus investigated using UV-visible spectroscopy, fluorescence spectroscopy, circular dichroism (CD), dynamic light scattering (DLS), dynamic fluorescence spectrum and molecular docking under physiological conditions. The intrinsic fluorescence quenching of BSA by CAPE was a static process, confirmed by the dynamic Fluorescence Spectrum. The negative values of ΔHmo and ΔSmo indicated that the hydrogen bond and van der Walls force played a predominant role in the enthalpy-driven binding process. The CD spectrum showed that after adding CAPE, the α-helix content structure of BSA decreased, and the secondary structure changed. At pH 6.0 and 8.5, the binding affinity of BSA to CAPE decreased. After adding metal ions, the binding affinity of BSA and CAPE increased. However, the presence of biosurfactants [sodium cholate (NaC) and sodium deoxycholate (NaDC)] decreased the binding affinity of BSA to CAPE because they all bound in the same subdomain of BSA.