Investigation of the Interaction Between Gallic Acid and α-Amylase by Spectroscopy

Abstract

Gallic acid is one of the important polyphenols in plants and it inhibits α-amylase. The interaction between gallic acid and α-amylase was investigated by fluorescence quenching spectroscopy, UV-vis spectroscopy, synchronous spectroscopy, and the three-dimensional fluorescence spectroscopy under mimic physiological conditions. The result of the emission quenching at different temperatures revealed that there are static quenching of intrinsic fluorescence of α-amylase induced by gallic acid and a complex of gallic acid-α-amylase was formed. The results obtained from the evaluation of three-dimensional fluorescence spectra, UV-vis spectra, and synchronous spectra suggested that the association between gallic acid and α-amylase did change the molecular conformation of α-amylase. Gallic acid can enter the primary substrate-binding pocket and alter the microenvironment around tryptophan and tyrosine residues.