On the dehydration of (R)-lactate in the fermentation of alanine to propionate by Clostridium propionicum.
All the enzymes of the pathway of (S)-alanine fermentation to acetate and propionate were detected in cell-free extracts of Clostridium propionicum . Among these (S)-glutamate dehydrogenase (NAD), (R)-lactate dehydrogenase (NAD) and propionate CoA-transferase were purified to apparent homogeneity. Their structures were presumably alpha 6, alpha 2 and alpha 4, respectively. The latter enzyme was specific for short-chain monocarboxylic acids with a pronounced preference for (R)-lactate over the (S)-enantiomer. The key step of the pathway, the dehydration of (R)-lactate required acetyl phosphate and CoASH under anaerobic conditions. It was inhibited by hydroxylamine, arsenate, azide (1 mM each) or by 0.1 mM 2,4-dinitrophenol. Thus it closely resembled the dehydration of (R)-2-hydroxyglutarate in Acidaminococcus fermentans , although an activation was not necessary.
D000409:Alanine / Q000378:metabolism*; D003013:Clostridium / Q000378:metabolism*; D015256:Coenzyme A-Transferases; D005285:Fermentation; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007773:Lactates / Q000378:metabolism*; D019344:Lactic Acid; D011422:Propionates / Q000378:metabolism*; D013237:Stereoisomerism; D013466:Sulfurtransferases / Q000378:metabolism
D007773:Lactates; D011422:Propionates; D019344:Lactic Acid; D007770:L-Lactate Dehydrogenase; D005969:Glutamate Dehydrogenase; D013466:Sulfurtransferases; D015256:Coenzyme A-Transferases; C031212:acyl-CoA transferase; C029658:propionic acid; D000409:Alanine