Volume 7, Issue 4 (12-2025)
pbp 2025, 7(4): 0-0 |
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saeidian S, khaliliaqdam N, salimi baneh S. The Effect of Temperature and Inhibitors Of Glycine and Cysteine on Cresolase Activity in Solanum lycopersicum under Immature and Mature Conditions. pbp 2025; 7 (4)
URL: http://pbp.medilam.ac.ir/article-1-293-en.html
URL: http://pbp.medilam.ac.ir/article-1-293-en.html
1- Associate Professor of Biochemistry, Faculty of Basic Sciences, Payame Noor University, Tehran, Iran
2- Associate Professor of Agricultural Sciences and Engineering, Faculty of Agriculture, Payame Noor University, Tehran, Iran ,nkhaliliaqdam@gmail.com
3- MSc in Biochemistry, Payame Noor University, Tehran, Iran
2- Associate Professor of Agricultural Sciences and Engineering, Faculty of Agriculture, Payame Noor University, Tehran, Iran ,
3- MSc in Biochemistry, Payame Noor University, Tehran, Iran
Abstract: (96 Views)
Objective: Polyphenol oxidase is a enzyme involved in phenolic substrate hydroxylation (cresolase) and oxidation (catecholase), processes critical for enzymatic browning in stored fruits and vegetables. Its activity depends on the type of substrate. PPO also generates reactive oxygen species and quinones, which can diminish the nutritional quality of proteins. The research focuses on analyzing cresolase activity of extracted from Solanum lycopersicum at immature and mature stages. The study evaluates optimal conditions such as pH, temperature, and substrate concentration, as well as glycine and cysteine as inhibitor.
Methods: Tomatoes from Kurdistan, at immature and mature stages, were processed to obtain extracts. Cresolase was evaluated across pH levels. Protein concentrations were quantified via the Bradford method, and kinetic parameters were calculated using varying p-cresol concentrations. Inhibitory effects of glycine and cysteine were assessed, and catecholase thermal stability under immature conditions was tested at different temperatures. Nonlinear regression models, supported by SAS and GraphPad Prism software, were applied to analyze and optimize enzymatic activity trends.
Results: The study identified pH 6.7 as optimal in both immature and mature samples. At 0.16 mM p-cresol concentration, Vmax was 0.15 units/mg protein, Km was 0.11 mM, and catalytic efficiency reached 1.37 units/mg protein/mM. Glycine exhibited stronger inhibition than cysteine, with IC50 values of 1.7 mM in mature and 0.4 mM in immature samples. Enzyme activity peaked at 45 minutes with inhibitors and 40 minutes without inhibitors. Glycine-treated samples exhibited slower declines in activity than cysteine-treated ones. Optimal performance was at 45°C without inhibitors and 40°C with inhibitors, while higher temperatures caused activity loss due to structural stress.
Conclusion: cresolase activity varies depending on pH, temperature, and inhibitors. Studies on kinetics and mathematical models can contribute to the development of strategies for controlling browning in food products and designing protective mechanisms for plants.
Methods: Tomatoes from Kurdistan, at immature and mature stages, were processed to obtain extracts. Cresolase was evaluated across pH levels. Protein concentrations were quantified via the Bradford method, and kinetic parameters were calculated using varying p-cresol concentrations. Inhibitory effects of glycine and cysteine were assessed, and catecholase thermal stability under immature conditions was tested at different temperatures. Nonlinear regression models, supported by SAS and GraphPad Prism software, were applied to analyze and optimize enzymatic activity trends.
Results: The study identified pH 6.7 as optimal in both immature and mature samples. At 0.16 mM p-cresol concentration, Vmax was 0.15 units/mg protein, Km was 0.11 mM, and catalytic efficiency reached 1.37 units/mg protein/mM. Glycine exhibited stronger inhibition than cysteine, with IC50 values of 1.7 mM in mature and 0.4 mM in immature samples. Enzyme activity peaked at 45 minutes with inhibitors and 40 minutes without inhibitors. Glycine-treated samples exhibited slower declines in activity than cysteine-treated ones. Optimal performance was at 45°C without inhibitors and 40°C with inhibitors, while higher temperatures caused activity loss due to structural stress.
Conclusion: cresolase activity varies depending on pH, temperature, and inhibitors. Studies on kinetics and mathematical models can contribute to the development of strategies for controlling browning in food products and designing protective mechanisms for plants.
Type of Study: Research |
Subject:
Phytochemistry
Received: 2025/04/14 | Accepted: 2025/05/26 | Published: 2025/12/1
Received: 2025/04/14 | Accepted: 2025/05/26 | Published: 2025/12/1
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