Laccase-catalyzed Conjugation of BSA Mediated by Gallic Acid: Preparation, Characterization, and Antioxidant Activity

Abstract

Laccase is one of the enzymes that catalyze the oxidation of phenolic and non-phenolic substrates and show encouraging potential as a biocatalyst in the synthesis of bioactive compounds. It is known that phenolic acids have an antioxidant effect. Bovine serum albumin (BSA) shows gelling activity, and nutraceutical binding ability but it does not show antioxidant activity. In this study, BSA which has no antioxidant activity using laccase, started to show antioxidant activity with gallic acid (GA) conjugation. The synthesized conjugates were analyzed by polyacrylamide gel electrophoresis (PAGE), ultraviolet–visible spectrophotometry (UV-Vis), and Fourier-transform infrared spectroscopy (FTIR). Radical scavenging capacity for antioxidant activity was measured. GA-functionalized-BSA displayed greatly improved 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging capacities, compared with the untreated BSA. Protein– flavonoid conjugates can improve the natural properties of proteins, being promising products to be used in medical, food and polymer fields where antioxidant ability is an essential feature. © 2022 Elsevier B.V., All rights reserved.