The carbanion of nitroethane is an inhibitor of, and not a substrate for, flavocytochrome b2 [L-(+)-lactate dehydrogenase].
Although nitroethane does not bind to the active site of flavocytochrome b2, its anion, ethane nitronate, behaves as a competitive inhibitor, with a Ki of 2.2 mM. No electron transfer can be detected between the nitronate and the enzyme, in contrast with the observations of other workers on D-amino acid oxidase. Propionate is a competitive inhibitor, with a Ki of 28 mM. The significance of these results with respect to the proposed carbanion mechanism and the putative existence of a covalent enzyme-substrate intermediate is discussed.
Genet
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R
Institut National de la Santé et de la Recherche Médicale Unité 25, Centre National de la Recherche Scientifique Unité Associëe 122, Hôpital Necker, Paris, France.
Lederer
F
F
D000473:Alkanes / Q000494:pharmacology*; D000838:Anions; D001667:Binding, Competitive; D004980:Ethane / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D042844:L-Lactate Dehydrogenase (Cytochrome); D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009595:Nitroparaffins / Q000378:metabolism / Q000494:pharmacology*; D011422:Propionates / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000201:enzymology
D000473:Alkanes; D000838:Anions; D007773:Lactates; D009595:Nitroparaffins; D011422:Propionates; D019344:Lactic Acid; C014705:nitroethane; D007770:L-Lactate Dehydrogenase; D042844:L-Lactate Dehydrogenase (Cytochrome); C029658:propionic acid; D004980:Ethane