Addition of ammonium salts to E. coli cells grown on a medium with glutamate as the sole nitrogen source is followed by rapid inactivation of glutamine synthetase (GS) I1 The active form of the enzyme (GSa) and the inactive form (GSb) have been isolated.2 Both forms behave similarly in the analytical ultracentrifuge, electrophoresis, and ion exchange chromatography. 2 In a cell-free system GSa ...

Glutamine synthetase, purified from rat liver, is homogeneous on acrylamide gel electrophoresis and on ultracentrifugation (~20,~) 15.0 S). The enzyme, which consists of eight subunits (subunit molecular weight, 44,000), resembles ovine brain glutamine synthetase in its physical properties, amino acid composition, and substrate specificity. Complete inhibition of the liver enzyme by methionine ...

The L-glutamine- and N-acetyl-L-glutamate-dependent carbamoyl phosphate synthetase III present in liver of spiny dogfish (Squalus acanthias) has been purified to a high state of purity. The purified enzyme has a Mr congruent to 160,000 and is subject to self-association which is facilitated by the presence of MgATP, L-glutamine, and N-acetyl-L-glutamate. The enzyme exhibits hysteretic propertie...

CTP synthetase is a cytosolic-associated glutamine amidotransferase enzyme that catalyzes the ATP-dependent transfer of the amide nitrogen from glutamine to the C-4 position of UTP to form CTP. In the yeast Saccharomyces cerevisiae, the reaction product CTP is an essential precursor of all membrane phospholipids that are synthesized via the Kennedy (CDP-choline and CDP-ethanolamine branches) an...

A carbamyl phosphate synthetase has been detected and partially characterized in hepatopancreas tissue of the land snail Strophocheitus oblongus. The enzyme is localized in mitochondria, utilizes L-glutamine, and shows an absolute requirement for N-acetyl-L-glutamate. This unique combination of properties distinguishes the snail enzyme from either of the previously described animal carbamyl pho...

The structural gene for glutamine synthetase (glnA) in Bacillus subtilis ( glnAB ) cloned in the lambda vector phage Charon 4A was used to transduce a lysogenic glutamine auxotrophic Escherichia coli strain to prototrophy. The defective E. coli gene ( glnAE ) was still present in the transductant since it could be transduced. In addition, curing of the prototroph resulted in the restoration of ...

We have demonstrated that Rhizobium leguminosarum strain LPR1105 contains a heat stable and a heat labile glutamine synthetase (EC 6.3.1.2) activity similar to those described for other Rhizobiaceae. Most of the activity is heat stable when this strain is grown on glutamine as sole nitrogen source, but most is heat labile when grown on nitrate. Using a gene bank of R. leguminosarum DNA we have ...

Anabaena oryzae ARM 570 was examined for its growth (chlorophyll and protein), heterocyst frequency, nitrogenase (acetylene reduction) activity, ammonia excretion, and glutamine synthetase and nitrate reductase in response to two levels of urea-N vis-à-vis N2-N. Growth of cyanobacterium increased with duration of incubation. Reduction in heterocyst frequency (40%) was observed at 30 ppm of urea...

The a-methyl and a-ethyl analogs of methionine sulfoximine, like methionine sulfoximine, induce convulsions in mice and inhibit glutamine synthetase irreversibly; cu-ethylmethionine sulfoximine is approximately 50% as inhibitory as methionine sulfoximine and a-methylmethionine sulfoximine. However, whereas cy-methylmethionine sulfoximine and methionine sulfoximine inhibit y-glutamylcysteine syn...