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On the dehydration of ( R )‐lactate in the fermentation of alanine to propionate by Clostridium propionicum
Author(s) -
Schweiger Georg,
Buckel Wolfgang
Publication year - 1984
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(84)80463-9
Subject(s) - propionate , chemistry , biochemistry , fermentation , lactate dehydrogenase , hydroxylamine , cofactor , enzyme , nad+ kinase
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 α 6 , α 2 and α 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.