[Kinetic manifestations of slow conformation rearrangements of lactate dehydrogenase. An experiment and a mathematical model].
Non-steady-state kinetics of lactate dehydrogenase (LDH) catalyzed reaction was investigated for a wide time interval (from 100 msec to 1-3 min) by using stopped-flow methods. A two-stage character of LDH reaction, slow changes like a lag-period on kinetic curves at pH 8.0, flexions on kinetic curves after pre-mixing LDH with NAD+ and pyruvate have been revealed. The graph theory for mathematical analysis of experimental data was applied, which has been developed for the non-steady-state kinetics. An enzyme model of the two-conformer LDH structure was used. The reaction scheme with a preferential inhibition of one of the conformers (pH 8.0) is suggested. The obtained values of kinetic constants prove that transitions between LDH conformers must be slow.
D000818:Animals; D066298:In Vitro Techniques; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D008954:Models, Biological; D009132:Muscles / Q000201:enzymology*; D011487:Protein Conformation; D013552:Swine; D013997:Time Factors
D007770:L-Lactate Dehydrogenase
Issledovanie kineticheskikh proiavleniĭ medlennykh konformatsionnykh perestroek v laktatdegidrogenaze. Eksperiment i matematicheskaia model'.