The metabolism of Brucellae: The oxidation of succinate as a function of pH and concentration

Abstract

A markedly disparate increase in the rate of uptake over the rate of oxidation of succinate in Brucella abortus results when the concentration of hydrogen ions or the substrate is grossly increased. The relation of this and other findings to possible alteration of the permeability of the cells has been considered in another paper (1). The present experiments

The metabolism of Brucellae: The nature of the effects of pH and concentration on the rate of oxidation of succinate

“…with increasing concentration of hydrogen ions or the substrate was further investigated in other experiments (8) and was found to be accounted for predominantly in greater accumulation of pyruvate xvith greater uptake of succinate. The respiratory quotients and the product-substrate ratios remained relatively constant, further indicating that the effect of the variables was not explainable by a shift in metabolic pathway.…”

“…The oxidation of L-glutamate through succinate with the accumulation of pyruvate and alanine (9), the relative constancy of MQO,(N) of glutamate with similar pH and concentration changes (l), and the marked increase of pyruvate accumulation from succinat'e oxidat,ion when the substrate uptake was increased by lowered pH (8) suggested a comparison between glutamate and succinate in the effect of pH on M&,(N), M&,(N), and the accumulation of intermediates with these substrates. If the pH change primarily affects the oxidation of succinat'e internally, then there should result comparable changes in the accumulation of the common intermediates.…”

“…However, the unpredicted quantitative difference (i.e. tenfold less pyruvate from glutamate) in the presumably common pathways lessened the usefulness of the data for the point in question, although they were of considerable interest metabolically (8). Alanine formation from glutamate (9) Tvas expected to account for this difference, but no alanine was found.…”