SUCCINIC ACID DECARBOXYLATION SYSTEM IN PROPIONIBACTERIUM PENTOSACEUM AND VEILLONELLA GAZOGENES

Abstract

Evidence presented indicates that during the decarboxylation of succinate to propionate and CO2 by cell-free extracts of P. pentosaceum and V. gazogenes, a 1-carbon fragment (C1) is produced from the y-car-boxyl carbon of succinyl-CoA, and that CO2 is subsequently produced from the C1 fragment by the action of an additional (and separate) enzyme system. Data include (a) non-stoichiometry of CO2 and propionate production from succinate; (b) "malonate block" experiments which indicated that the C1 fragment could be incorporated''into the malate carboxyl group; (c) propionate "exchanged" with succinate by combination with a C1 fragment arising from succinate decarboxylation; (d) CO2 production from succinate by combinations of cell-free extracts of both organisms showed that at least 2 separate enzyme reactions were involved between succinyl-CoA decarboxylation and the production of CO2; and (e) comparison of the ratios of C14o2 and propionate-1-C14 arising from the decomposition of (asymmetrically) labeled succinyl-4-C14-CoA and of (symmetrically) labeled succinyl-l,4-C14-CoA demonstrated that the C1 fragment arose from the unactivated succinate carboxyl carbon atom.