Velocity of specific selective enzymes in mango [Mangifera indica L.] treated with y- Rays

This study aimed to investigate to what extend the 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 gamma-rays; namely, 500, 1000, 1500, 2500 and 5000 Gy produced from Co60. The velocity reaction of the aforementioned enzymes in relation to different substrate and enzyme concentrations were studied. The kinetic properties in terms of affinity, maximum velocity, activity coefficient and slope of reaction were calculated through a specific computer program [enzyme kinetics]. The changes in the velocity patterns of the investigated enzymes as affected by storage for three weeks at 20 +/- 2C were also studied. On the basis of the obtained results, it was found that a dose of 2500 Gy could be recommended to reach a higher inhibition level of the three tested enzymes, a pattern which improves the quality and extends the shelf-life of mango fruit

Conjugation of proteins and enzymes with hydrophilic polymers and their applications.

The efficacy of a number of therapeutically active proteins and peptides is severely limited due to their instability in circulation. Of the various approaches used to stabilise these proteins, the one more successful is covalent modification of the protein or enzyme with some hydrophilic polymers such as dextran or PEG. These conjugates are more stable than the native protein both in vitro as well as in vivo. They exhibit enhanced resistant to proteolytic degradation, have a long-life in circulation and exhibit reduced immunogenicity. The therapeutic efficacy of these conjugates is also greatly enhanced compared to the native protein or enzyme.