Citric Acid Cycle Metabolites Research Articles

Effects of x-irradiation on 14C-pyruvate metabolism in rat thymocytes.

Incorporation of 14C-pyruvate into the citric acid cycle metabolites was measured in rat thymocytes X-irradiated in vitro. X-irradiation caused no significant changes in 14C-pyruvate incorporation into the metabolites separated by Dowex-1 formate column chromatography. Glycogen content of the cells decreased, whereas malate showed a significant accumulation after irradiation. From the results, the previously reported increase in labeling of citric acid cycle metabolites derived from 14C-glucose was explained as the result of the enhanced glycolysis in the thymocytes after irradiation.

Kinetic Properties of Rabbit Testicular Lactate Dehydrogenase Isozyme

Abstract The additional lactate dehydrogenase isozyme from rabbit testis and sperm, lactate dehydrogenase isozyme-1 (B4) from heart, and lactate dehydrogenase isozyme-5 (A4) from liver have been separated and partially purified by preparative starch gel electrophoresis. Studies performed on these fractions comprised Km and optimum substrate concentration for pyruvate, α-ketobutyrate, and lactate, inhibition by substrate and product, effect of oxamate, oxalate, urea, some citric acid cycle metabolites, pH, and heating. Results indicate that rabbit testicular lactate dehydrogenase isozyme is a distinct molecular form with peculiar catalytic properties. It showed different behavior against high substrate concentrations whether the direct or the reverse reaction was studied: striking inhibition by pyruvate, no effect with lactate. There is a remarkable correlation between these properties and metabolic requirements of mature spermatozoa.