Glyceraldehyde Phosphate Dehydrogenase, Phosphoglycerate Kinase, and Phosphoglyceromutase of Escherichia coli

A relatively simple seven-step procedure is described whereby glyceraldehyde phosphate dehydrogenase, phosphoglyceromutase, and phosphoglycerate kinase can be purified from extracts of Escherichia coli. The purified preparations (50 to 100 mg) of the first two enzymes were homogeneous when examined by polyacrylamide gel electrophoresis at pH 9 and by sedimentation techniques. The purified fraction of phosphoglycerate kinase contained small amounts of contaminating proteins. The molecular weights and s20, w0 values of the purified proteins were, respectively: glyceraldehyde phosphate dehydrogenase, 144,000 and 7.5 S; phosphoglycerate kinase, 43,700 and 3.5 S; and phosphoglyceromutase, 56,300 and 4.8 S. The amounts of these enzymes in cell extracts varied with the carbon source which the cells utilized during growth, but the three activities were invariably present in constant proportion to one another. Calculation of the number of molecules of each enzyme present in such extracts indicated a nonequimolar distribution (ratio of glyceraldehyde phosphate dehydrogenase to phosphoglycerate kinase to phosphoglyceromutase, 1:2.4:3.6).