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 ...

The activity of micrococcal nuclease was studied on a novel substrate, denatured adenylylated glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2], which contains a unique tyrosyl residue linked through a phosphodiester bond to 5'-AMP. The products of the digestion were adenosine and O-phosphotyrosylglutamine synthetase. The Km of the macromolecular substrate with the nuc...

The majority of the phosphotyrosine recovered from partial acid hydrolysates of 32P-labeled Escherichia coli is derived from a single prominent protein. We show here by biochemical, genetic, and immunological criteria that this protein is actually glutamine synthetase adenylylated (not phosphorylated) at tyrosine. Furthermore, all of the phosphotyrosine detectable in partial acid hydrolysates o...

The gene for glutamate dehydrogenase (gdhD) has been mapped in Klebsiella aerogenes by P1 transduction. It is linked to pyrF and trp with the order pyrF-trp-gdh. Complementation analysis using F' episomes from Escherichia coli suggests an analogous location in E. coli. Two mutants able to produce glutamate dehydrogenase in the presence of high levels of glutamine synthetase have been isolated. ...

PurposeOur purpose was to better understand the pathogenesis of seizures associated with angiocentric glioma. Angiocentric glioma is an indolent and rare low-grade Its typical clinical presentation epileptic seizures. The tumor-associated poorly understood. Among possible pathomechanisms, increased neurotoxic concentrations glutamate has been proposed. Glutamate transporters, pyruvate carboxyla...