Formation of adducts of pyridine nucleotides in the active center of swine lactate dehydrogenase (isoenzyme M4)
Volkova, T.D.; Kalacheva, N.I.; Vorontsov, E.A.; Mal'tsev, N.I.; Shchors, E.I.
Biokhimiia 41(1): 58-67
1976
ISSN/ISBN: 0320-9725 PMID: 179605 Document Number: 103581
Isozyme M4 of pig lactate dehydrogenase (LDH-M4) catalyzes reaction of NAD-adduct formation with a nucleophylic agent that is perhaps OH--ion. The T 1/2 of the reaction is 10-30 sec at concentration NAD 2,0-10(-3) M, LDH-M4 50 gamma/ml at pH greater than 8. Initial velocity and limit of the reaction increase at high LDH-M4, NAD and OH--ion concentrations. Pyridine-3-aldehyde and 3-acetyl pyridine analogs of NAD forms fluorescent adducts too, but at OH--ion concentration approximately 0,01 of that in the case of NAD reaction. Isoelectrical point of LDH-M4 determined by isoelectrofocusing method is 8,65 +/- 0,04 pH unit.