The levels of several enzymes involved in assimilation of different nitrogen compounds were investigated in Streptomyces clavuligerus in relation to the nitrogen source supplied to the cultures. Threonine dehydratase, serine dehydratase, proline dehydrogenase, histidase and urocanase were not decreased in the presence of ammonium. The latter two enzymes were induced by histidine in the culture ...

In the physiological condition, glutamate acts as an excitatory neurotransmitter in the retina. However, excessive glutamate can be toxic to retinal neurons by overstimulation of the glutamate receptors. Glutamate excess is primarily attributed to perturbation in the homeostasis of the glutamate metabolism. Major pathway of glutamate metabolism consists of glutamate uptake by glutamate transpor...

We investigated the effect of methionine sulfoximine (MetSox), a potent inhibitor of glutamine synthetase, on Mycobacterium tuberculosis. M. tuberculosis encodes four glutamine synthetases, of which MetSox targets the type I enzyme encoded by glnA1. Transcriptional profiling revealed that glutamate synthetase (gltB) and a type II glutamine synthetase (glnA3) were induced after exposure to MetSo...

Glutamine synthetase (GS) utilizes various substituted glutamic acids as substrates. We have used this information to design herbicidal alpha- and gamma-substituted analogs of phosphinothricin (l-2-amino-4-(hydroxymethylphosphinyl)butanoic acid, PPT), a naturally occurring GS inhibitor and a potent herbicide. The substituted phosphinothricins inhibit cytosolic sorghum GS(1) and chloroplastic GS...

In Streptomyces sp. 3022a, anthranilate synthetase is composed of two non-identical subunits. The major subunit (molecular weight, 72,000) converts chorismic acid to anthranilic acid, using ammonia as the source of the amino group. The smaller subunit (molecular weight 28,000 to 29,000) confers on the enzyme the ability to use glutamine instead of ammonia as a substrate. In this study, reactivi...