Formate Metabolism

It was incidentally observed in this laboratory that crystalline preparations of formyltetrahydrofolate synthetase from CEostridium cylindrosporum catalyze the activation of formate by adenosine triphosphate in the absence of tetrahydrofolate.Efforts to determine whether the tetrahydrofolate-independent reaction is catalyzed by formyltetrahydrofolate synthetase led eventually to the discovery of two formate kinases in extracts of C. cylindrosporum which catalyze the formation of formyl phosphate.It was further established that formyl phosphate serves as a formyl donor for the synthesis of formyl coenzyme A in a reaction catalyzed by phosphate acetyltransferase.It is the purpose of this communication to summarize the results of these experiments.EXPERIMENTAL PROCEDURE &fate&& Dried cells of C. cylindrosporum were prepared from cultures grown in a 400~liter industrial fermenter' in the medium described by Rabinowitz and Barker (1).The nucleotide triphosphates, diphosphates, and Co.4 were purchased from Pabst Laboratories.ADP-MY4 was purchased from Schwarz BioResearch, Inc. Dilithium acetyl-P was prepared as described by Stadtman (2).Formyl-P was prepared by using the elegant synthesis of Jaenicke and Brode (3),* which involves formylation of dipotassium phosphate with formyl fluoride.The formyl fluoride for this synthesis was prepared by Dr. Lin Tsai of this laboratory according to the method of Olah and Kuhn (4).Formyl-CoA was prepared as described in the previous paper (5).Authentic formylhydroxamate was prepared by the method of Hestrin (6), and a crystalline sample was the generous gift of Dr. L. Jaenicke.dnalytical Procedures Acylthioesters and acyl phosphates were assayed by the hydroxamate procedure (2) .3Orthophosphate was measured i Dr. T. C. Stadtman adapted the growth conditions for use in the industrial fermenter,