Pyruvate metabolism in Halobacterium salinarium studied by intracellular 13C nuclear magnetic resonance spectroscopy.
13C nuclear magnetic resonance spectroscopy was used to study the metabolism of [2-13C]pyruvate in intact cells of Halobacterium salinarium. The spectra of these cells show that pyruvate is reduced to lactic acid and transaminated to alanine. The intensity of C-2 lactate is higher under anaerobic conditions than under aerobic conditions. When cells are grown in the absence of glucose, the level of C-2 lactate intensity is lower. In extracts of these cells, the level of NADH-dependent lactate dehydrogenase activity is lower than that of cells grown in the presence of glucose. A C-5 glutamate resonance suggests the entry of pyruvate into the tricarboxylic acid cycle through acetyl-coenzyme A. In addition, the label is also observed at C-3 and C-4 of glutamate, signifying a pyruvate carboxylase-type reaction and scrambling of label at the fumarate-succinate stage plus malic enzyme operation, respectively. Citrate synthase and malic enzyme activity appear to be controlled by the growth conditions of H. salinarium.
Bhaumik
S R
SR
Chemical Physics Group, Tata Institute of Fundamental Research, Bombay, India.
Sonawat
H M
HM
D000409:Alanine / Q000378:metabolism; D002247:Carbon Isotopes; D002952:Citric Acid Cycle / Q000502:physiology*; D006217:Halobacterium / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009682:Magnetic Resonance Spectroscopy; D011773:Pyruvates / Q000378:metabolism*; D019289:Pyruvic Acid
D002247:Carbon Isotopes; D007773:Lactates; D011773:Pyruvates; D019344:Lactic Acid; D019289:Pyruvic Acid; D000409:Alanine