Kinetic behaviour and oligomeric state of 3-phosphoglyceroyl-D-glyceraldehyde-3-phosphate dehydrogenase

The specific activity of pig muscle D-glyceraldehyde-3-phosphate dehydrogenase was found to be constant in the reverse reaction, with NADH and 1,3-diphosphoglycerate as substrates, over the enzyme concentration range 10(-8) to 10(-4) M. The molecular weight of the covalent intermediate of the enzyme, 3-phosphoglyceroyl-glyceraldehyde-3-phosphate dehydrogenase, as measured by sedimentation techniques, proved constant (145 000 +/- 6 000) between 3 x 10(-5) M enzyme concentration. Likewise, no change in the apparent molecular weight was observed by gel-chromatography even at 2 x 10(-8) M enzyme concentration. The data indicate that the enzyme functions in its tetrameric form.