کنگره بین المللی زیست فناوری گیاهان دارویی و قارچ های کوهی

صفحه اصلی / پنجمین کنگره بین المللی و ششمین همایش ملی زیست فناوری گیاهان دارویی و قارچ های کوهی

Biochemical Behavior of Peroxidase in Different Physiological Growth Conditions of Solanum lycopersicum in Response to Cysteine and Glycine

نویسندگان :

Seyedeh zahra Moosavi¹ Zhila Zareie²

1- دانشگاه پیام نور 2- دانشگاه پیام نور

کلمات کلیدی :

solanum Lycopersicum،kinetics،Peroxidase،cysteine،glycine

چکیده :

Abstract Tomato (Solanum lycopersicum), as a model plant in the Solanaceae family, is highly valued for its nutritional, genetic, and physiological traits. Under biotic and abiotic stress conditions, reactive oxygen species (ROS), such as hydrogen peroxide (H₂O₂), accumulate and damage cellular structures. Ascorbate peroxidase (APX) plays a crucial role in maintaining redox balance by converting H₂O₂ into water through the ascorbate-glutathione cycle. This study aimed to investigate the kinetic behavior and thermal stability of APX in three developmental stages of tomato (immature, ripe, and post-storage), and to evaluate the effects of two inhibitors, cysteine and glycine. Samples were prepared, homogenized, and centrifuged, and the crude extract was used to measure enzyme activity. APX activity was assessed by monitoring the decrease in absorbance at 290 nm, and data were analyzed using statistical tests. Results showed that the maximum reaction rate (Vmax) increased progressively from the immature to the ripe and post-storage stages, indicating the plant’s response to elevated oxidative stress during development. The decrease in Michaelis constant (Km) reflected enhanced substrate affinity and catalytic efficiency under stress conditions. The type of inhibition varied with developmental stage; cysteine exhibited stronger inhibition due to its thiol group, suggesting a regulatory role in redox balance, while glycine showed milder effects. Optimal temperature for APX activity also shifted depending on growth stage and inhibitor presence, indicating structural adaptation of the enzyme to environmental conditions. These findings highlight the regulatory role of APX in antioxidant defense and its potential application in postharvest stress management.