Regulatory enzymes of carbohydrate metabolism in the giant scallop Placopecten Magellanicus (Gmelin).

O'Doherty, Patrick James Anthony (1970) Regulatory enzymes of carbohydrate metabolism in the giant scallop Placopecten Magellanicus (Gmelin). Masters thesis, Memorial University of Newfoundland.

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Abstract

It would appear from the relative activities of key glycolytic enzymes, that succinate is the main end product of glycolysis in both the mantle and the adductor muscle of the giant scallop. The pathway of succinate formation appears to be similar to that postulated for other invertebrates. All the enzymes but one catalyzing the formation of succinate in the mantle and the adductor muscle were found in the cytosol. The enzyme catalyzing the reduction of fumarate was found in the mitochondrial fraction. -- The enzymes of the Bucher Shuttle were found in the adductor muscle. Thus two mechanisms are readily available in the adductor muscle for the oxidation of cytoplasmic NADH, viz. the malate dehydrogenase system and the Bucher Shuttle. -- The high activities of phosphoenolpyruvic carboxykinase and fructose diphosphatase are compatible with active glycogen synthesis in the adductor muscle, and it appears the dicarboxylic acid shuttle is the mechanism by which the pyruvate kinase step is bypassed, as pyruvate carboxylase is absent. -- The effects of known metabolic regulators of other systems were studied on several of the carbohydrate enzymes of the adductor muscle. Many showed similar properties to mammalian enzymes, although some interesting differences were found. -- Studies on the thermal properties of the enzymes showed that the Km was influenced by temperature and that the effect of some metabolic regulators were temperature-dependent. It would appear temperature may be an important parameter in metabolic control in the scallop.

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