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Wen Y, Sun J, Jia H, Qi X, Mao X. Inactivation of polyphenol oxidase by low intensity DC field: Experiment and mechanism analysis via molecular dynamics simulation and molecular docking. Food Res Int 2024; 188:114325. [PMID: 38823824 DOI: 10.1016/j.foodres.2024.114325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 04/01/2024] [Accepted: 04/16/2024] [Indexed: 06/03/2024]
Abstract
In this study, inactivation of mushroom polyphenol oxidase (PPO) by low intensity direct current (DC) electric field and its molecular mechanism were investigated. In the experiments under 3 V/cm, 5 V/cm, 7 V/cm and 9 V/cm electric fields, PPOs were all completely inactivated after different exposure times. Under 1 V/cm, a residual activity of 11.88 % remained. The inactivation kinetics confirms to Weibull model. Under 1-7 V/cm, n value closes to a constant about 1.3. The structural analysis of PPO under 3 V/cm and 5 V/cm by fluorescence emission spectroscopy and molecular dynamics (MD) simulation showed that the tertiary structure was slightly changed with increased radius of gyration, higher potential energy and rate of C-alpha fluctuation. After exposure to the electric field, most of the hydrophobic tryptophan (TRP) residues turned to the hydrophilic surface, resulting the fluorescence red-shifted and quenched. Molecular docking indicated that the receptor binding domain of catechol in PPO was changed. PPO under electric field was MD simulated the first time, revealing the changing mechanism of the electric field itself on PPO, a binuclear copper enzyme, which has a metallic center. All these suggest that the low intensity DC electric field would be a promising option for enzymatic browning inhibition or even enzyme activity inactivation.
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Affiliation(s)
- Yanbing Wen
- State Key Laboratory of Marine Food Processing and Safety Control, College of Food Science and Engineering, Ocean University of China, Qingdao 266404, PR China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, PR China; Qingdao Key Laboratory of Food Biotechnology, Qingdao 266404, PR China; Key Laboratory of Biological Processing of Aquatic Products, China National Light Industry, Qingdao 266404, PR China
| | - Jing Sun
- State Key Laboratory of Marine Food Processing and Safety Control, College of Food Science and Engineering, Ocean University of China, Qingdao 266404, PR China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, PR China; Qingdao Key Laboratory of Food Biotechnology, Qingdao 266404, PR China; Key Laboratory of Biological Processing of Aquatic Products, China National Light Industry, Qingdao 266404, PR China
| | - Hongxin Jia
- State Key Laboratory of Marine Food Processing and Safety Control, College of Food Science and Engineering, Ocean University of China, Qingdao 266404, PR China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, PR China; Qingdao Key Laboratory of Food Biotechnology, Qingdao 266404, PR China; Key Laboratory of Biological Processing of Aquatic Products, China National Light Industry, Qingdao 266404, PR China
| | - Xiangming Qi
- State Key Laboratory of Marine Food Processing and Safety Control, College of Food Science and Engineering, Ocean University of China, Qingdao 266404, PR China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, PR China; Qingdao Key Laboratory of Food Biotechnology, Qingdao 266404, PR China; Key Laboratory of Biological Processing of Aquatic Products, China National Light Industry, Qingdao 266404, PR China.
| | - Xiangzhao Mao
- State Key Laboratory of Marine Food Processing and Safety Control, College of Food Science and Engineering, Ocean University of China, Qingdao 266404, PR China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, PR China; Qingdao Key Laboratory of Food Biotechnology, Qingdao 266404, PR China; Key Laboratory of Biological Processing of Aquatic Products, China National Light Industry, Qingdao 266404, PR China
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In Vitro Measurement of Sphingolipid Intermembrane Transport Illustrated by GLTP Superfamily Members. Methods Mol Biol 2019; 1949:237-256. [PMID: 30790260 DOI: 10.1007/978-1-4939-9136-5_17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Herein, we describe methodological approaches for measuring in vitro transfer of sphingolipids (SLs) between membranes. The approaches rely on direct tracking of the lipid. Typically, direct tracking involves lipid labeling via attachment of fluorophores or introduction of radioactivity. Members of the GlycoLipid Transfer Protein (GLTP) superfamily are used to illustrate two broadly applicable methods for direct lipid tracking. One method relies on Förster resonance energy transfer (FRET) that enables continuous assessment of fluorophore-labeled SL transfer in real time between lipid donor and acceptor vesicles. The second method relies on tracking of radiolabeled SL transfer by separation of lipid donor and acceptor vesicles at discrete time points. The assays are readily adjustable for assessing lipid transfer (1) between various model membrane assemblies (vesicles, micelles, bicelles, nanodiscs), (2) involving other lipid types by other lipid transfer proteins, (3) with protein preparations that are either crudely or highly purified, and (4) that is spontaneous and occurs in the absence of protein.
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