Some enzymic reactions concerned in the metabolism of acetoacetyl-coenzyme A in Athiorhodaceae

Abstract

Ceil-free extracts of photosynthetic bacteria of the Athiorhodaceae family form acetoacetate from acetyl phosphate in the presence of phospho-[image] transacetylase and coenzyme A. Such extracts are rich in fi -ketothiolase and coenzyme A transferase. The extracts contained [beta]-hydroxy-[beta]-methyl-glutaryl-coenzyme A cleavage enzyme. Neither the formation of [beta]-hydroxy[beta]-methylglut.aryl-coenzyme A from acetoacetyl-coenzyme A and acetyl-coenzyme A, nor its reduction to mevalonic acid by reduced triphosphopyridine nucleotide, was detected. The level of activity of these enzymes, and of [beta] -hydroxybutyrate dehydrogenase and [beta]-hydroxy-butyryl-coenzyme A dehydrogenase, did not differ significantly in extracts prepared from pigmented and non-pigmented organisms.