Effect of--SH compounds and catecholamines on radiosusceptibility of testicular hyaluronidase
Sharma, P.K.; Gupta, G.S.
Indian Journal of Biochemistry and Biophysics 24(4): 218-224
1987
ISSN/ISBN: 0301-1208 PMID: 3436631 Document Number: 289822
The effect of various doses of gamma-irradiation on testicular hyaluronidase in solution has been studied. An exponential relation between residual activity and irradiation dose was generally obtained. A linear relation between enzyme concentration and D37 indicated that the radiation damage of hyaluronidase in solution is mostly due to the radiolytic products of water. A horizontal linear relation between the concentration and concentration/D37 has suggested that the energy required for inactivation does not depend on concentration of enzyme. Number of events occurring per 100 eV of absorbed dose (G value) of hyaluronidase was 0.08. Sham-irradiated enzyme was not affected by melatonin, whereas dopamine stimulated hyaluronidase activity. On the other hand, cysteine and reduced glutathione were effective inhibitors, and the inhibition was dependent on the relative proportion of enzyme and cysteine or glutathione present in the mixture. Semi-log plots of residual activity versus dose on irradiation have indicated that although melatonin and dopamine protect hyaluronidase activity, cysteine and glutathione are unable to show a significant protection. When hyaluronidase was irradiated at varying pH (3.2-6.8), maximum residual activity was obtained at 4.8. Role of aspartic and glutamic acids in radio-protection at pH 4.8 has been suggested.