α-Glycerophosphate dehydrogenase

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Abstract
The preparation of an active [alpha]-glycerophosphate dehydrogenase from muscle is described. The influence of pH, methylene blue concn., substrate concn. and partial pressure of O on the rate of enzymic oxidation was studied. The dehydrogenase oxidised only ([long dash]) [alpha]-glycerophosphate, the natural muscle isomeride. Evidence is presented that glyceraldehydephosphate is the principal oxidation product. The possibility that di-hydroxyacetonephosphate is also formed was not excluded. Methylglyoxal is formed as a decomposition product of the triosephosphate. The enzyme was not inhibited by KCN or NaN3 but was inhibited by octyl alcohol and ethylurethane. NaF and iodacetate in concns. which poison glycolytic processes had no action on the dehydrogenase. The dehydrogenase did not catalyse the reaction between [alpha]-glycerophosphate and pyruvate. Evidence is presented that the dehydrogenase was not the enzyme responsible for this reaction in the glycolytic cycle. Flavoprotein, flavin, ascorbic acid and adrenaline did not catalyse the reaction of the dehydrogenase system with molecular O. Cytochrome c of heart and yeast were the only common natural carriers which were active with this system. The cytochrome effect was analyzed and it was shown that, under suitable conditions, cytochrome was reduced and oxidized about 300 times per min. The dehydrogenase is considered to be anaerobic in the sense that it does not react with O in absence of a suitable carrier. The enzyme is widely distributed in animal tissues, and in the rabbit is found in the highest concn. in the brain. When extracted from tissues, it is found associated with particles and cannot be brought into solution.

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