Quantitative histochemistry of the primate skin. III. Glyceraldehyde-3-phosphate dehydrogenase.

Glyceraldehyde-3-phosphate dehydrogenase activities were assayed with a fluorometric micromethod in various parts of the skin and its appendages. Enzyme activity was abundant, particularly in the epidermis and mucous membrane (4.2 to 11.3 moles/hr/kg dry wt.). The keratin layer of sole epidermis also contained a considerable amount of enzyme activity (2.6 moles/hr/kg dry wt.). A relatively low activity was found in the apocrine and sebaceous glands (1.8 to 3.6 moles/hr/kg dry wt.). The enzyme was influenced by various activators and inhibitors. The activators were 1-cysteine (200% increase), mercaptoethanol (+300%), EDTA (+300%), and the inhibitors, pCMB, Cu++ and Co++ (nearly 100% inhibition). Either arsenate or orthophosphate was an absolute requirement for the enzyme reaction. It is speculated that this dehydrogenase in skin and appendages may be a regulator of the Pasteur effect, hence of glycolysis, as it may be in muscle or in ascites tumor cells.