The Effect of Tumor Growth on Hepatic Threonine Dehydrogenase.

The enzyme in Rhodopseudomona@ spheroides requires DPN as a co-factor (13) and has been called threonine dehydrogenase (14). Aminoacetone can also be synthesized by the condensa tion of glycine and acetyl CoA to form a-amino-@-keto butyric acid (6, 10, 21, 22). This reaction is analogous to that involved in the biosynthesis of 5-aminolevulinic acid, the aliphatic precursor of porphyrins, and was first proposed by Shemin in 1956 (16). The role of aminoacetone in metabolic processes has been studied by several investigators. Shemin demon strated that the carbon bearing the amino group can be converted to 002 or formate, or incorporated into the