This family of CoA transferases includes enzymes catalyzing at least two related but distinct activities. The E. coli YgfH protein has been characterized as a propionyl-CoA:succinate CoA transferase where it appears to be involved in a pathway for the decarboxylation of succinate to propionate. The Clostridium kluyveri CAT1 protein has been characterized as a acetyl-CoA:succinate CoA transferase and is believed to be involved in anaerobic succinate degradation. The propionate:succinate transferase activity has been reported in the propionic acid fermentation of propionibacterium species, where it is distinct from the coupled activities of distinct nucleotide-triphosphate dependent succinate and propionate/acetate CoA transferases (as inferred from activity in the absence of NTPs). The family represented by this model includes a member from Propionibacterium acnes KPA171202 which is likely to be responsible for this activity. A closely related clade not included in this family are the Ach1p proteins of fungi which are acetyl-CoA hydrolases. This name has been applied to many of the proteins represented by this model, possibly erroneously.
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