Rate Of Succinate Oxidation Research Articles

Malic enzyme activity in blowfly muscle.

AN investigation of the metabolism of sarcosomes and whole-muscle homogenates isolated from the flight-muscle of the blowfly (Calliphora erythrocephala) indicated that the rate of succinate oxidation by these preparations is limited by the steady-state concentration of oxaloacetate produced by further oxidation of fumarate (Lewis, S. E., and Price, G. M., unpublished observations).

Die α-Glycerophosphat-Oxydation des Heuschreckenbrustmuskels (Locusta migratoria)

The conditions were studied for the glycerophosphate oxidation by homogenate from locust flight muscle, and the O2-consumption was measured. Maximal oxidation rates were found with 0.087m glycerophosphate, 8 × 10−6m cytochromec, 7 × 10−6m DPN and pH 7.5. The production of dihydroxyacetone phosphate is followed by further oxidation steps, as could be shown by estimation of the different fractions of acid-soluble phosphate. Comparative studies were made on different insects and vertebrates. The rate of succinate oxidation by insect muscle was found to be ten times higher than that of vertebrate muscle. The relation of glycerophosphate oxidation to succinate oxidation is quite different in insects and vertebrates, but no difference could be detected between the two types of muscle metabolism of insects: the carbohydrate and the fatutilizing type.

The effect of glucose in the growth medium on the succinic acid oxidizing system of Escherichia coli.

Manometric determinations have been made of the rate of succinate oxidation by washed Escherichia coli cells derived from a glucose-containing medium. Succinate oxidation is initially slow but after 50-60 minutes the rate increases to a steady level. The duration of the lag period is markedly increased by excessive washing of the cells. With minimally washed cells the final activity may be reduced as a result of competitive inhibition due to endogenous substrates. Conditions of suspension preparation must be carefully standardized to obtain maximum activities and reproducible effects. Results obtained indicate that the enzyme system responsible for the oxidation of succinate is formed when Escherichia coli is grown in a glucose medium and that the lag period can be more satisfactorily explained on the basis of a temporary impermeability of the cell to succinate rather than a period of enzyme adaptation.