Biomedical subjects

C A PASTERNAK

Publications and source records attributed to C A PASTERNAK.

15 recordsLinked to original sources

PubMed1965

FURTHER STUDIES ON THE REGULATION OF AMINO SUGAR METABOLISM IN BACILLUS SUBTILIS.

1. Glucosamine 6-phosphate deaminase [2-amino-2-deoxy-d-glucose 6-phosphate ketol-isomerase (deaminating), EC 5.3.1.10] of Bacillus subtilis has been partially purified. Its K(m) is 3.0mm. 2. Extracts of B. subtilis contain N-acetylglucosamine 6-phosphate deacetylase (K(m) 1.4mm), glucosamine 1-phosphate acetylase and amino sugar kinases (EC 2.7.1.8 and 2.7.1.9). 3. Glucosamine 6-phosphate synthetase (l-glutamine-d-fructose 6-phosphate aminotransferase, EC 2.6.1.16) is repressed by growth of B. subtilis in the presence of glucosamine, N-acetylglucosamine, N-propionylglucosamine or N-formylglucosamine. Glucosamine 6-phosphate deaminase and N-acetylglucosamine 6-phosphate deacetylase are induced by N-acetylglucosamine. Amino sugar kinases are induced by glucose, glucosamine and N-acetylglucosamine. The synthesis of glucosamine 1-phosphate acetylase is unaffected by amino sugars. 4. Glucose in the growth medium prevents the induction of glucosamine 6-phosphate deaminase and of N-acetylglucosamine 6-phosphate deacetylase caused by N-acetylglucosamine; glucose also alleviates the repression of glucosamine 6-phosphate synthetase caused by amino sugars. 5. Glucosamine 6-phosphate deaminase increases in bacteria incubated beyond the exponential phase of growth. This increase is prevented by glucose.

Acetylglucosamine↗

PubMed1965

THE INCORPORATION OF LABELLED AMINO SUGARS BY BACILLUS SUBTILIS.

1. N-Acetyl[1-(14)C]glucosamine (10mum-5mm) is incorporated by cells of Bacillus subtilis at a constant rate (0.2-2mmumoles/mg. dry wt./hr.). The rate of [1-(14)C]glucosamine (2.5mum-5mm) incorporation is proportional to the concentration; it approaches that of N-acetyl[1-(14)C]glucosamine at 5mm. 2. Label from N-acetyl-[1-(14)C]glucosamine and [1-(14)C]glucosamine is incorporated predominantly into the ;hot-trichloroacetic acid-soluble' and ;residue' fractions of cells. Acid hydrolysis of the hot-trichloroacetic acid-soluble fraction yields mainly [(14)C]glucosamine; hydrolysis of the residue fraction yields [(14)C]glucosamine and [(14)C]muramic acid. The label from N-[1-(14)C]acetylglucosamine and sodium [1-(14)C]acetate enters most cell fractions. Incorporation of N-[1-(14)C]acetylglucosamine is inhibited by the addition of unlabelled acetate. 3. Glucose competes with [1-(14)C]glucosamine for incorporation. N-Propionylglucosamine and N-formylglucosamine compete with N-acetyl[1-(14)C]glucosamine. 4. Cells pregrown on N-acetylglucosamine or glucosamine incorporate up to ten times as much N-acetyl[1-(14)C]glucosamine or [1-(14)C]glucosamine in a given time as cells pregrown on glucose.

Acetates↗

PubMed1965

THE CONTROL OF SULPHATE REDUCTION IN BACTERIA.

1. An enzyme from Escherichia coli 9723 that reduces adenosine 3'-phosphate 5'-sulphatophosphate to inorganic sulphite is described. Extracts of E. coli K(12) and Bacillus subtilis 1379 contain a similar enzyme. 2. This reductase and sulphite reductase (EC 1.8.1.2) of E. coli 9723, E. coli K(12) and of B. subtilis are repressed by growth in the presence of l-cystine. Cysteine synthase (EC 4.2.1.22) is unaffected. 3. Growth of E. coli 9723 on inorganic sulphite represses the sulphate-activating enzymes (EC 2.7.7.4 and 2.7.1.25) almost completely but has little effect on sulphite reductase. Growth on 0.042-0.056mm-l-cystine gives a similar result. 4. Such differential repression by cyst(e)ine prevents E. coli, when growing on sulphite, from synthesizing unnecessary enzymes.

Adenine Nucleotides↗

PubMed1965

THE CONTROL OF SULPHATE ACTIVATION IN BACTERIA.

1. ATP-sulphate adenylyltransferase (EC 2.7.7.4) and ATP-adenylyl sulphate 3'-phosphotransferase (EC 2.7.1.25) of Escherichia coli 9723, E. coli K(12) and Bacillus subtilis 1379 are each repressed by growth in the presence of cystine. Repression of the two enzymes in E. coli 9723 may be co-ordinate. 2. ATP-sulphate adenylyltransferase of Desulphovibrio desulphuricans, in which sulphate reduction is linked to the energy supply of the organism, is not repressed by growth in the presence of inorganic sulphite or cysteine. 3. Leuconostoc mesenteroides lacks all the enzymes between sulphate and cysteine whether grown on cysteine or glutathione.

Bacillus subtilis↗

PubMed1964