The problem at hand is dealing with; to what extend velocities of polyphenol oxidase (PPO), peroxidase
(POD) and pectinmethylesterase (PME) are affected by irradiation?. To reach such target, the investigated mango
fruits were irradiated with different doses of γ- rays namely .500, 1000, 1500, 2500 and 5000 Gy produced from Co60.
Velocity reaction of the aforementioned enzymes in relation to different substrate and enzyme concentrations were
studied. Kinetic properties in terms of affinity, maximum velocity, activity coefficient, and slope of reaction were
calculated through a specific computer program namely “Enzyme kinetics". Changes in the velocity patterns of the
investigated enzymes as affected by storage for three weeks at 20±2oC were also studied. On the basis of the obtained
results, it was found that a dose of 2500 Gy could be recommended to reach higher inhibition level of the three tested
enzymes, a pattern which improves the quality and extends shelf-life of mango fruit.