Function of malate synthetase and isocitritase in the growth of bacteria on two-carbon compounds

Reeves, Henry C. (Albert Einstein Medical Center, Philadelphia, Pa.) and Samuel J. Ajl. Function of malate synthetase and isocitritase in the growth of bacteria on two-carbon compounds. J. Bacteriol. 83:597-601. 1962.-Escherichia coli, grown in a glucose-citrate medium under anaerobic conditions, is devoid of the enzymes malate synthetase and isocitritase. It has been demonstrated that the adaptation of such cells to aerobic growth in a medium containing acetate as the sole carbon source involves at least two separate events. The first appears to be an adaptation which permits the oxidative dissimilation of acetate and involves primarily the synthesis of condensing enzyme. The second, which also precedes all division, is the synthesis of isocitritase and malate synthetase. Finally, a definite correlation has been found to exist between the synthesis of isocitritase and malate synthetase and the lag period prior to cell proliferation.

Role of citritase in acetoin formation by Streptococcus diacetilactis and Leuconostoc citrovorum

Harvey, R. J. (University of California, Davis) and E. B. Collins. Role of citritase in acetoin formation by Streptococcus diacetilactis and Leuconostoc citrovorum. J. Bacteriol. 82:954-959. 1961.-Cell-free extracts of Streptococcus diacetilactis and Leuconostoc citrovorum converted citrate to acetate, oxalacetate, pyruvate, carbon dioxide, and acetoin. The products, stoichiometry, and cofactor requirements of the citrate-splitting reaction were identical to those reported for citritase. Coenzyme A was not required; the reaction was stimulated by magnesium or manganous ions, and inhibited by calcium ions. In S. diacetilactis the enzyme is constitutive; it has been found inducible in all other organisms that have been studied. Ten strains of S. diacetilactis, three strains of Leuconostoc, and one strain of S. liquefaciens contained the enzyme; 21 strains of S. cremoris and 3 strains of S. lactis did not. Cell-free extracts of S. diacetilactis and L. citrovorum converted pyruvate to acetoin and carbon dioxide in the presence of manganous ions and thiamine pyrophosphate.

Observations on the substrate specificity of DOPA decarboxylase from ox adrenal medulla, human phaeochromocytoma and human argentaffinoma

The substrate specificity of the dopa decarboxylases of ox adrenal medulla, human phaeochromocytoma and human argentaffinoma have been studied. The enzymes from all three tissues decarboxylated dopa, metatyrosine, orthotyrosine and 5-hydroxytryptophan. Dopa was decarboxylated most rapidly and 5-hydroxytryptophan least rapidly by the enzyme from all three tissues. Competition experiments indicate that all four substrates are decarboxylated by the one enzyme. Attempts to demonstrate decarboxylation of [C(14)]-tyrosine, [C(14)]-tryptophan or [C(14)]-histidine by these enzyme preparations were unsuccessful.

Decarboxylase inhibition and blood pressure reduction by alpha-methyl-3,4-dihydroxy-DL-phenylalanine

alpha-Methyl-3,4-dihydroxy-DLphenylalanine has been found to be an effective inhibitor of aromatic amino acid decarboxylation in man. This was shown by decreased formation of serotonin, tryptamine, and tyramine from the precursor amino acids. Reduction of amine biosynthesis is associated with lowering of blood pressure in hypertensive patients and a transient sedative effect.

Nutrition and metabolism of marine bacteria. X. The glyoxylate cycle in a marine bacterium

Extracts of a species of marine bacterium have been shown to contain isocitratase and malate synthetase when cells were grown in a medium in which acetate was the sole source of carbon and energy. Neither enzyme could be demonstrated in extracts prepared from cells grown in a nutrient broth, yeast extract medium.