Molecular inactivation of testicular hyaluronidase in solid state after proton irradiation: a study based on target size, substrate binding and thermodynamic analysis of heat denaturation.

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dc.contributor.authorGupta, G Sen_US
dc.contributor.authorSharma, P Ken_US
dc.date.accessioned1995-10-01en_US
dc.date.accessioned2009-05-27T09:30:58Z
dc.date.available1995-10-01en_US
dc.date.available2009-05-27T09:30:58Z
dc.date.issued1995-10-01en_US
dc.description.abstractDose response activity curve of testicular hyaluronidase (HDase) following proton irradiation in dry state follows complicated mechanisms which may involve multiple hits and multiple targets of variable sizes giving a constant G value of 1.66. Target analysis appears to be modified by slow recovery of activity when irradiated enzyme is brought to aqueous phase. However, pattern of irradiation at a dose of 1 x 10(5) to 8 x 10(5) Gy reveals that though binding affinity of enzyme to the substrate (hyaluronic acid) increases as shown by declining Km from 500 mg/l to 300-70 mg/l, the reaction rate of catalysis by irradiated HDase is decreased due to decrease in reaction velocity (Vmax: 266 versus 76 units at 8 x 10(5) Gy). Activation analysis of heat denaturation of nonirradiated HDase suggested the involvement of 78 kcal/mole of energy of activation (E*a) which declined to 63-52 k cal/mole after irradiation at 1 x 10(5) to 8 x 10(5) Gy for residual enzyme. The corresponding change in entropy of activation (delta S*) increased from a control value of -291 eu to -236 eu at 8 x 10(5) Gy. From thermodynamic analysis in association with recovery in aqueous phase, it is concluded that HDase is inactivated due to dissipation of proton energy among weak forces including H bonds associated with secondary/tertiary structure of molecules.en_US
dc.description.affiliationDepartment of Biophysics, Panjab University, Chandigarh, India.en_US
dc.identifier.citationGupta GS, Sharma PK. Molecular inactivation of testicular hyaluronidase in solid state after proton irradiation: a study based on target size, substrate binding and thermodynamic analysis of heat denaturation. Indian Journal of Biochemistry & Biophysics. 1995 Oct; 32(5): 266-71en_US
dc.identifier.urihttps://imsear.searo.who.int/handle/123456789/27740
dc.language.isoengen_US
dc.source.urihttps://https://www.niscair.res.in/ScienceCommunication/ResearchJournals/rejour/ijbb/ijbb0.aspen_US
dc.subject.meshAnimalsen_US
dc.subject.meshHot Temperatureen_US
dc.subject.meshHyaluronoglucosaminidase --radiation effectsen_US
dc.subject.meshMaleen_US
dc.subject.meshProtein Denaturationen_US
dc.subject.meshProtonsen_US
dc.subject.meshSheepen_US
dc.subject.meshSubstrate Specificityen_US
dc.subject.meshTestis --enzymologyen_US
dc.subject.meshThermodynamicsen_US
dc.titleMolecular inactivation of testicular hyaluronidase in solid state after proton irradiation: a study based on target size, substrate binding and thermodynamic analysis of heat denaturation.en_US
dc.typeJournal Articleen_US
dc.typeResearch Support, Non-U.S. Gov'ten_US
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