Regularities in the kinetic of photoactivation of lactate dehydrogenase by the action of UV light in different microenvironment
Artiukhov, V.G.; Lysenko, I.A.; Nakvasina, M.A.
Biofizika 45(3): 427-431
2000
ISSN/ISBN: 0006-3029 PMID: 10872053 Document Number: 518640
The kinetics of photoinactivation of cardiac (H4) and muscular (M4) isoforms of lactate dehydrogenase irradiated by UV light (240-390 nm) in the free form and in the presence of sodium azide, D-mannitol, and serotonin was studied. It was shown that the decrease in the catalytic activity of both enzymes can be described by the kinetics of the first-order monomolecular reaction. The inactivation rate constant of lactate dehydrogenase M4 is considerably higher than that of lactate dehydrogenase H4, indicating a greater photochemical lability of the isoform M4. It was shown that sodium azide has a different protective action on the proteins studied. The irradiation of the muscular isoform in the presence of serotonin and D-mannitol did not change the character of the "dose-effect" curve and only led to a decrease in the photoinactivation rate constant of the protein.