EC Number   |
Substrates |
Organism  |
Products |
Reversibility |
|---|
   4.3.1.B2 | more |
the enzyme also shows glutaminase activity. The glutaminase activity of the glutaminase domain is tightly regulated by the acceptor substrate domain. In IGP synthase the glutaminase and N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate binding sites are separated by 30 A. Using kinetic analyses of site-specific mutants and molecular dynamic simulations, it is determined that an interdomain salt bridge in IGP synthase between D359 and K196 (approximately 16 A from the N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate binding site) plays a key role in mediating communication between the two active sites. This interdomain contact modulates the glutaminase loop containing the histidine and glutamic acid of the catalytic triad to control glutamine hydrolysis |
Saccharomyces cerevisiae |
? |
- |
? |
| 4.3.1.B2 | more |
the enzyme shows a low basal level glutaminase activity that can be enhanced 1000fold in the presence of a nucleotide substrate or analog |
Saccharomyces cerevisiae |
? |
- |
? |
| 4.3.1.B2 | more |
the glutaminase activity of the enzyme is stimulated 4900fold in the presence of the acceptor substrate N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate |
Saccharomyces cerevisiae |
? |
- |
? |
| 4.3.1.B2 | NH4+ + N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate |
- |
Saccharomyces cerevisiae |
D-erythro-1-(imidazol-4-yl)glycerol phosphate + 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide |
- |
? |
| 4.3.1.B2 | L-glutamine + H2O |
the enzyme constitutes a bienzyme complex of the glutaminase subunit HisH and the synthase subunit HisF. Nascent ammonia produced by HisH reacts at the active site of HisF with N'-((5'-phosphoribulosyl)formimino)-5-aminoimidazole-4-carboxamide-ribonucleotide to yield the products imidazoleglycerol phosphate and 5-aminoimidazole-4-carboxamide ribotide. Isolated subunit HisH shows no detectable glutaminase activity but is stimulated by complex formation with subunit HisF to which either the product imidazole glycerol phosphate or a substrate analogue are bound |
Thermotoga maritima |
L-glutamate + NH3 |
- |
? |
| 4.3.1.B2 | L-glutamine + N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-monophosphate |
the enzyme catalyzes two different reactions at two separate active sites. At the glutaminase active site, glutamine is hydrolyzed to glutamate and ammonia, which, at the synthase active site, reacts with the acceptor substrate N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-monophosphate. Ammonia is channeled between glutaminase and synthase active sites |
Thermotoga maritima |
L-glutamate + D-erythro-1-(imidazol-4-yl)glycerol phosphate + 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide |
- |
? |
| 4.3.1.B2 | L-glutamine + N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-monophosphate |
the enzyme constitutes a bienzyme complex of the glutaminase subunit HisH and the synthase subunit HisF. Nascent ammonia produced by HisH reacts at the active site of HisF with N'-((5'-phosphoribulosyl)formimino)-5-aminoimidazole-4-carboxamide-ribonucleotide to yield the products imidazole glycerol phosphate and 5-aminoimidazole-4-carboxamide ribotide. Isolated subunit HisH shows no detectable glutaminase activity but is stimulated by complex formation with subunit HisF to which either the product imidazole glycerol phosphate or a substrate analogue are bound |
Thermotoga maritima |
L-glutamate + D-erythro-1-(imidazol-4-yl)glycerol phosphate + 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide |
- |
? |
| 4.3.1.B2 | L-glutamine + N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate |
- |
Thermotoga maritima |
L-glutamate + D-erythro-1-(imidazol-4-yl)glycerol phosphate + 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide |
- |
? |
| 4.3.1.B2 | N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate + NH3 |
the enzyme constitutes a bienzyme complex of the glutaminase subunit HisH and the synthase subunit HisF. Nascent ammonia produced by HisH reacts at the active site of HisF with N'-((5'-phosphoribulosyl)formimino)-5-aminoimidazole-4-carboxamide-ribonucleotide to yield the products imidazole glycerol phosphate and 5-aminoimidazole-4-carboxamide ribotide. Isolated subunit HisH shows no detectable glutaminase activity but is stimulated by complex formation with subunit HisF to which either the product imidazole glycerol phosphate or a substrate analogue are bound |
Thermotoga maritima |
D-erythro-1-(imidazol-4-yl)glycerol phosphate + 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide |
- |
? |
| 4.3.1.B2 | NH4+ + N1-[(5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamido-1-beta-D-ribofuranosyl 5'-phosphate |
- |
Thermotoga maritima |
D-erythro-1-(imidazol-4-yl)glycerol phosphate + 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide |
- |
? |
