Kinetic and Thermal Stability of Catecholase in Tomato (Solanum Lycopersicum) in the Presence of Glycine and Cysteine

Saeidian, Shahriar; Khalili Aqdam, Nabi; Fathi, Mokhtar; Solati Pooralkaran, Maryam

doi:10.22034/jpr.2026.8600.3401

Kinetic and Thermal Stability of Catecholase in Tomato (Solanum Lycopersicum) in the Presence of Glycine and Cysteine

Articles in Press

Document Type : Research Paper

Authors

shahriar saeidian ¹

nabi khalili aqdam ²

mokhtar Fathi ³

maryam Solati pooralkaran ⁴

¹ Biology department of payam noor university

² department of agriculture, payame noor university

³ Department of agriculture, payam noor university

⁴ department of Biology, payame noor university

10.22034/jpr.2026.8600.3401

Abstract

In this study, catecholase activity in tomatoes (Solanum lycopersicum) was investigated under unripe and ripe conditions. The main objective of the study was to investigate the effect of pH, amino acids, and temperature on catecholase activity and the catalytic efficiency of the enzyme under different ripening conditions. Catecholase activity was observed in tomatoes (Solanum lycopersicum) under both unripe and ripe conditions. The optimal pH for catecholase activity varied depending on the type of substrate. Glycine and cysteine amino acids acted as inhibitors, reducing catecholase activity and catalytic efficiency. The catalytic efficiency was higher under ripe conditions. The decrease in Km under ripe conditions indicated a higher affinity of catecholase for catechol, which was confirmed by an increase in maximum velocity (Vmax) of catecholase activity in all three conditions (in the presence and absence of amino acids). At low substrate concentrations, the enzyme had a high affinity and consumed the substrate quickly, while increasing the substrate concentration increased the enzyme's affinity, likely due to conformational changes. The type of inhibition of catecholase by glycine and cysteine was independent of the substrate type and dependent on the inhibitor type, and the ripeness or unripeness of the tomato had no effect on it. C

Keywords

Catecholase

Kinetics

Cysteine

Glycine

Solanum lycopersicum

Subjects