2.7.2.8 2-oxoglutarate complete inhibition at 0.5 mM 34 2.7.2.8 ADP - 13 2.7.2.8 ADP inhibitor of complex formation with PII protein 13 2.7.2.8 arginine feedback regulation of enzyme and N-acetylglutamate synthase is mutually interdependent, enzymes form a complex 532 2.7.2.8 arginine pH-optimum for inhibition is 7.5 532 2.7.2.8 arginine allosteric enzyme which is inhibited by arginine 532 2.7.2.8 arginine enzyme has no allosteric properties and its activity is influenced neither by arginine nor by any of the intermediates of the arginine biosynthetic pathway 532 2.7.2.8 arginine feedback inhibition is markedly dependent on pH, above pH 9 no inhibition 532 2.7.2.8 arginine 1 mM, 96% inhibition 532 2.7.2.8 arginine feedback inhibition 532 2.7.2.8 arginine - 532 2.7.2.8 ATP - 4 2.7.2.8 L-arginine pH and temperature dependent, sigmoidal dependence on concentration of arginine, Hill coefficient of 4, 1 mM, 37°C, 95% inhibition 123 2.7.2.8 L-arginine only for N-acetylglutamate synthase activity 123 2.7.2.8 L-arginine less inhibitory in the presence of the PII protein 123 2.7.2.8 L-arginine sigmoidal arginine inhibition kinetics, feedback inhibition, indentification of the N-terminal arginine site, mutational analysis, the mobile alphaH-beta16 loop of the arginine site is the modulatory signal receiver, overview 123 2.7.2.8 L-arginine - 123 2.7.2.8 L-arginine complete inhibition at 3-5 mM, PII-mediated relief from L-arginine inhibition is antagonized by 2-oxoglutarate 123 2.7.2.8 L-arginine complete inhibition at 0.1-1.0 mM, PII-mediated relief from L-arginine inhibition is antagonized by 2-oxoglutarate 123 2.7.2.8 L-arginine an allosteric inhibitor of mmNAGS/K, mechanism of allosteric inhibition of mmNAGS/K by L-arginine. L-Arginine is an allosteric inhibitor of NAGS/K but an allosteric activator of mammalian NAGS. In contrast to the structure of mmNAGS/K in the absence of L-arginine where there are conformational differences between the four subunits in the asymmetric unit, all four subunits in the L-arginine liganded structure have very similar conformations. In this conformation, the AcCoA binding site in the N-acetyltransferase domain is blocked by a loop from the amino acid kinase domain, as a result of a domain rotation that occurs when L-arginine binds 123 2.7.2.8 L-arginine feedback inhibition. SYPA5-5 N-acetylglutamate kinase feedback inhibition by L-arginine can be deregulated by introducing point mutations, H268N or R209A 123 2.7.2.8 L-arginine feedback inhibition, almost complete inhibition at 10 mM 123 2.7.2.8 L-arginine wild type enzyme activity drastically decreases by addition of 0.2 mM L-Arg, and consequently decreases when L-Arg concentration is increased, indicating that the enzyme activity is subject to feedback inhibition by L-Arg. Enzyme activity is almost lost in the presence of 1.0 mM L-Arg 123 2.7.2.8 L-arginine methyl ester 1 mM, 80% inhibition 6543 2.7.2.8 L-canavanine - 1143 2.7.2.8 L-citrulline - 938 2.7.2.8 MgCl2 inhibition above 20 mM 196 2.7.2.8 MgCl2 30 mM, slight inhibition 196 2.7.2.8 additional information not inhibitory: D-arginine, agmatine, citrulline, L-canavanine, L-lysine, L-ornithine, guanidinium ions, urea at 1 mM, 37°C 2 2.7.2.8 additional information the enzyme is L-arginine-insensitive 2 2.7.2.8 trichloroacetic acid complete inactivation at 30% 48176