Caffeoyl substitution changes the inhibition mode of tartaric acid against α-amylase: Analysis of the enzyme inhibition by four caffeic and tartaric acid derivates. (November 2020)

• Record Type: Journal Article
• Authors: Bai, Fangting; Wang, Yueyi; Zhang, Shanbo; Wang, Yutang; Zhang, Jifan; Cao, Junwei; Sun, Lijun
• Is Part Of: Lebensmittel-Wissenschaft + Technologie =. Volume 133(2020)
• Publication Date: 2020-11
• Subjects: α-Amylase -- Inhibition -- Tartaric acid -- Caffeoyl moiety -- Binding interactions; Food industry and trade -- Periodicals; Food -- Composition -- Periodicals; Microbiology -- Periodicals; Nutrition -- Periodicals; 664.005
• DOI: 10.1016/j.lwt.2020.109942
• Languages: English
• ISSNs: 0023-6438

Abstract

Abstract: α-Amylase inhibition by four dietary organic acids was characterized by inhibition assay, kinetics, fluorescence quenching and molecular docking. Tartaric acid was found as an uncompetitive inhibitor, with 2, 3-OH playing an important role in binding with the enzymic non-active site. Although caffeic acid had a low inhibitory activity, caffeoyl substitution at 2, 3-OH of tartaric acid gradually increased its competitive inhibition character. As a result, caftaric acid (one caffeoyl-substituted) and chicoric acid (two caffeoyl-substituted) were suggested as mixed-type and competitive inhibitors, respectively, despite that the substitution decreased the inhibitory activity of tartaric acid. Fluorescence quenching was only observed for compounds with caffeoyl(s), and the effect increased with the moiety number increasing, consistent with the changing trend in number of active fluorescent residues involved in ligand-enzyme interactions. These results suggest that caffeoyl moiety entered into α-amylase active pocket. Therefore, caffeoyl has potentials as a functional-factor in α-amylase inhibition for alleviating type-II diabetes symptoms. Highlights: Tartaric acid was a typical uncompetitive inhibitor of α-amylase. Fluorescence quenching effect was not significantly observed for tartaric acid. Caffeoyl substitution increased competitive inhibition character of tartaric acid. Fluorescent amino acid residues were involved docking with caffeoyl moiety. Caffeoyl was indicated to enter into and bind with enzyme active site.