Allen, S. H. G. (Western Reserve University, Cleveland, Ohio), R. W. Kellermeyer, R. L. Stjernholm, and Harland G. Wood. Purification and properties of enzymes involved in the propionic acid fermentation. J. Bacteriol. 87:171-187. 1964.-Chromatographic procedures are described for the separation and purification of phosphotransacetylase, acetyl kinase, malic dehydrogenase and coenzyme A (CoA) transferase. Purity of the enzymes was judged by homogeneity in an ultracentrifuge and by specific activity. Phosphotransacetylase was obtained 85% pure with a specific activity of 27.1. The preparation of acetyl kinase was a homogeneous protein with a specific activity of 531. The malic dehydrogenase likewise was homogeneous with a specific activity of 938. The CoA transferase, which was about 56% pure with a specific activity of 42.6, is the purest preparation of this enzyme yet described. The pH optimum was 6.5 to 7.8, and the K(m) for succinyl-CoA in the transfer of CoA to acetate was found to be 1.3 x 10(-4)m; for acetate, in the same transfer, the K(m) was 7.0 x 10(-3)m; for succinyl-CoA to propionate it was 6.8 x 10(-5)m, and for propionate, in the same reaction, 6.2 x 10(-4)m. Methods are described for the enzymatic production of methyl-malonyl-CoA, malonyl-CoA, propionyl-CoA, acetyl-CoA, and succinyl-CoA. The role of these enzymes in the propionic acid fermentation as well as the possible mechanism responsible for the high yields of adenosine triphosphate from glucose are considered.