CARBON ASSIMILATION BY <i>PSEUDOMONAS OXALATICUS</i> (OX 1). 7. DECARBOXYLATION OF OXALYL-COENZYME A TO FORMYL-COENZYME A

Abstract

Oxalyl-coenzyme A has been implicated in the decarboxylation of oxalate in an oxalate-grown bacterium by Jakoby, Ohmura & Hayaishi (1956), who suggested this series of reactions:Quayle, Keech & Taylor (1961) concluded that de- carboxylation of oxalate by crude extracts of oxalate-grown Pseudomonas oxalaticus followed reactions (1)-( 3) except that acetyl-CoA is replaced in (1) by succinyl-CoA and, in addition, a trans- ferase is present capable of transferring the CoA grouping from formyl-CoA to either succinate or oxalate.Koch & Jaenicke (1962) also refer to decarboxylation of oxalate by extracts of a species of Pseudomonas in which phosphate, CoA and thiamine pyrophosphate were cofactors for the reaction.This paper records a study of the decarboxylation of oxalyl-CoA and oxalate in crude extracts of P. oxalaticus, and the purification from such extracts of an enzyme that catalyses reaction (2).Part of this work has been communicated to The Biochemical Society (Quayle, 1963b). MATERIALS AND METHODSAbbreviation.TPP, Thiamine pyrophosphate.Special chemicals.Oxalyl-CoA was prepared by thiol ester interchange between CoA and thiocresyl hydrogen oxalate and was assayed by the use of oxalyl-CoA reductase (Quayle, 1963a).[14C2]0xalyl-[12C]CoA was prepared by a similar method from thiocresyl hydrogen [l"C2]oxalate.The latter compound was prepared from [14C2]oxalyl chloride according to the method of Stolle (1914).Succinyl-CoA was prepared by the reaction of CoA with succinic anhydride (Simon, 1957).Malonyl-CoAwasgivenbyProfessorF.Lynen (Max Planck