The changes in photosynthetic activity, as well the activity of nitrogen-metabolism enzymes, intensity lipid peroxidation, and proline content were studied Triticum aestivum L. plants after their incubation at a low CO2 concentration sealed chamber for 10 d. deficiency (-CO2) compared to normal (control) led decrease rate O2 gas exchange plateau light cur...

The effects of adenine nucleotides on pea seed glutamine synthetase (EC 6.3.1.2) activity were examined as a part of our investigation of the regulation of this octameric plant enzyme. Saturation curves for glutamine synthetase activity versus ATP with ADP as the changing fixed inhibitor were not hyperbolic; greater apparent Vmax values were observed in the presence of added ADP than the Vmax o...

Maize glutamine synthetase cDNA clones were isolated by genetic selection for functional rescue of an Escherichia coli delta glnA mutant growing on medium lacking glutamine. The Black Mexican Sweet cDNA library used in this study was constructed in pUC13 such that cDNA sense strands were transcribed under the control of the lac promoter. E. coli delta glnA cells were transformed with cDNA libra...

The present study was conducted to investigate the allelopathic activity of Rumex dentatus aqueous leaf extract on metabolites, reactive oxygen species (ROS), and enzymes activities in Portulaca oleraceae. results showed a reduction carbohydrates, protein, DNA, RNA contents. However, total phenolics, flavonoids, malondialdehyde were enhanced. ROS such as hydrogen peroxide, superoxide radicals, ...

In whole cells of Rhodopseudomonas sphaeroides, nitrogen fixation, as measured by hydrogen production and acetylene reduction, was totally inhibited by micromolar concentrations of ammonia. This inhibition could not be duplicated by glutamate or glutamine alone. The inhibition by ammonia was abolished by methionine sulfoximine, a glutamine synthetase inhibitor. Inhibition by glutamine was compl...

stimulates glutamine release at the expense of tissue glutamate while decreasing or having little effect on alanine release (Ruderman & Lund, 1972; Chang & Goldberg, 1978). In the perfused rat hindlimb total glutamine production by resting muscle is over 4-fold greater than ammonia production, but the addition of methionine sulphoximine (a glutamine synthetase inhibitor) reverses this pattern (...

Anthranilate synthetase from Serratia marcescens was purified to homogeneity. Criteria for homogeneity were disc gel electrophoresis, sedimentation analysis, and immunodiffusion. During electrofocusing the enzyme was found to have an isoelectric pH of 4.6. Glutamineand ammoniadependent activities superimposed during electrofocusing. Glutamine-dependent activity showed a pH optimum of 7.6, while...

Biochemical studies suggest that excitatory neurons are metabolically coupled with astrocytes to generate glutamate for release. However, the extent to which glutamatergic neurotransmission depends on this process remains controversial because direct electrophysiological evidence is lacking. The distance between cell bodies and axon terminals predicts that glutamine-glutamate cycle is synaptica...

Carbamyl phosphate synthetase (from Escherichia coli) consists of a 7.3S protomeric unit that contains one heavy polypeptide chain (molecular weight about 130,000) and one light chain (molecular weight about 42,000). The heavy and light chains were separated by gel filtration in the presence of 1 M potassium thiocyanate. In contrast to the native enzyme and the reconstituted enzyme (prepared by...