Regulation of the activity of the Bacillus licheniformis A5 glutamine synthetase.
AUTOR(ES)
Donohue, T J
RESUMO
The regulation of glutamine synthetase activity by positive and negative effectors of enzyme activity singularly and in combinations was studied by using a homogeneous enzyme preparation from Bacillus licheniformis A5. Phosphorylribosyl pyrophosphate at concentrations greater than 2mM stimulated glutamine synthetase activity by approximately 70%. The concentration of phosphorylribosyl pyrophosphate required for half-maximal stimulation of enzyme activity was 0.4 mM. Results obtained from studies of fractional inhibition of glutamine synthetase activity were consistent with the presence of one allosteric site for glutamine binding (apparent I0.5, 2.2mM) per active enzyme unit at a glutamate concentration of 50 mM. At a glutamate concentration of 30 mM or less, the data were consistent with the enzyme containing two binding sites for glutamine (one of which was an allosteric site with an apparent I0.5 of 0.4 mM). Bases on an analysis of the response of glutamine synthetase activity to positive and negative effectors in vitro and to the intracellular concentration of these effectors in vivo, the primary modulators of glutamine synthetase activity in B. licheniformis A5 appear to be glutamine and alanine (apparent I0.5, 5.2mM).
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=216179Documentos Relacionados
- Properties of the Bacillus licheniformis A5 glutamine synthetase purified from cells grown in the presence of ammonia or nitrate.
- Regulation of Glutamine Synthetase VI. Interactions of Inhibitors for Bacillus licheniformis Glutamine Synthetase
- Regulation of Glutamine Synthetase V. Partial Purification and Properties of Glutamine Synthetase from Bacillus licheniformis
- Regulation of synthesis of glutamine synthetase by adenylylated glutamine synthetase.
- Regulation of glutamine synthetase. 8. ATP: glutamine synthetase adenylyltransferase, an enzyme that catalyzes alterations in the regulatory properties of glutamine synthetase.
