[Thermostabilization of glutamin(asparagin)ase from Pseudomonas aurantica BKMB-548].
In studies on kinetics of thermoinactivation of glutaminase (asparaginase) from Ps. arantiaca BKMB-548 at 50 degrees and pH 7.0 in presence or in absence of L-glutamate the enzyme inactivation was found to obey the first order equation. Both the glutaminase and asparaginase activities decreased at a similar rate. L-Glutamate stabilized the enzyme due to direct interaction with its molecule. Stability of the complex formed was evaluated quantitatively. L-Glutamate reacted apparently with a specific site on the surface of the enzyme molecule; Kdiss was 0.42 +/- 0.03 mM at pH 7.0 and 50 degrees. No cooperative effect was found. L-Aspartate protected the enzyme completely; stabilizing effects of L-cysteine, L-serine and glycine were similar to the effect of L-glutamate (94%, 84%, 83% and 82%, respectively). At the same time, glutarate, succinate, alpha-ketobutyrate, alpha-ketoglutarate, gamma-aminobutyrate and N-benzoyl glutamate did not exhibit the stabilization effect. The data obtained suggest that the high stabilizing effect might exhibit only the substances containing simultaneously free alpha-NH2 and alpha-COOH groups in a molecule, whereas presence of COOH groups at beta--or gamma-carbon atoms was not essential for the stabilizing effect.
D000581:Amidohydrolases / Q000037:antagonists & inhibitors*; D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D006358:Hot Temperature; D007700:Kinetics; D011549:Pseudomonas / Q000201:enzymology*; D012970:Sodium Glutamate / Q000494:pharmacology; D013379:Substrate Specificity
D000581:Amidohydrolases; C020654:glutamin-(asparagin-)ase; D012970:Sodium Glutamate
Termostabilizatsiia glutamin(asparagin)azy iz Pseudomonas aurantiaca BKMB-548.