ELECTROPHORETIC STUDIES ON PHOSPHATASES FROM THE PANCREATIC ISLETS OF OBESE-HYPERGLYCAEMIC MICE

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Abstract
Disc-electrophoresis on polyacrylamide gels was used for the separation of phosphatases from the pancreatic islets of American obese-hyperglycaemic mice. Three sites of enzyme activity involving inosine diphosphate, adenosine diphosphate and thiamine pyrophosphate were observed and their apparent substrate specificity and sensitivity to various ions examined. By comparison with the epididymis, it was concluded that the different enzyme activities most probably represented alkaline phosphatase, thiamine pyrophosphatase and Golgi-associated nucleoside diphosphatase. The activity of the last enzyme was measured in the endocrine and exocrine pancreas of fed and starved animals by densitometric scanning of the stained gels. The Golgi-associated nucleoside-diphosphatase activity was found to be about 4 times higher in the islets than in the acinar tissue, starvation of the animals for 7 days being without effect. The relative activities of two different molecular varieties of non-specific acid phosphatase were assayed after the isoenzymes had been extracted from the polyacrylamide gels. In the liver and endocrine pancreas the most rapidly migrating enzyme had the highest activity. Most of the enzyme activity from the exocrine pancreas, on the other hand, was found in the slow band.