Different modes of inhibition for organic acids on polyphenoloxidase. (15th May 2016)

• Record Type: Journal Article
• Authors: Zhou, Lei; Liu, Wei; Xiong, Zhiqiang; Zou, Liqiang; Chen, Jun; Liu, Junping; Zhong, Junzhen
• Is Part Of: Food chemistry. Volume 199(2016)
• Page Start: 439
• Page End: 446
• Publication Date: 2016-05-15
• Subjects: Polyphenoloxidase -- Organic acid -- pH -- Inhibitory mode -- Conformation -- Molecular docking; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2015.12.034
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Inhibition of PPO induced by citric or malic acid was due to the decrease of pH. Cinnamic acid reversibly inhibited PPO in a mixed-type manner. Citric acid, malic acid and cinnamic acid quenched fluorescence in different modes. Cinnamic acid bound to PPO and induced the rearrangement of secondary structure. Abstract: It is still unclear whether the inhibitory effect of organic acid on polyphenoloxidase (PPO) is due to the reversible inhibition or decrease of pH. In this study, cinnamic acid, citric acid and malic acid inhibited PPO in different modes. Results showed that the inhibition by cinnamic acid resulted from reversible inhibition, while the decrease of pH was the main cause for citric acid and malic acid. The kinetic results showed that cinnamic acid reversibly inhibited PPO in a mixed-type manner. Fluorescence emission spectra indicated that cinnamic acid might interact with PPO and quench its intrinsic fluorescence, while the decrease of the fluorescence intensity induced by citric acid or malic acid was due to the acid-pH. Cinnamic acid bound to PPO and induced the rearrangement of secondary structure. Molecular docking result revealed cinnamic acid inserted into the hydrophobic cavity of PPO by forming π–π stacking.