Algal glyceraldehyde-3-phosphate dehydrogenase. Pyridine-nucleotide requirements of two enzymes purified from Scenedesmus obliquus.

Two enzymes with glyceraldehyde-3-phosphate dehydrogenase activity have been purified from heterotrophically grown Scenedesmus obliquus by ion-exchange chromatography and gel filtration. The D-enzyme has a molecular weight of 550000 and a VNADH: VNADPH ratio of 16 whereas the T-enzyme has a molecular weight of 140000 and a VNADH:VNADPH ratio of 0.15. The two enzymes, however, are very similar with regard to their Michaelis constants for the reduced pyridine nucleotides, pH optimum, subunit size and ultraviolet absorption.