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Literature summary extracted from

  • Hoskins, A.A.; Morar, M.; Kappock, T.J.; Mathews, I.I.; Zaugg, J.B.; Barder, T.E.; Peng, P.; Okamoto, A.; Ealick, S.E.; Stubbe, J.
    N5-CAIR mutase: role of a CO2 binding site and substrate movement in catalysis (2007), Biochemistry, 46, 2842-2855.
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

EC Number Cloned (Comment) Organism
5.4.99.18 expression in Escherichia coli Escherichia coli

Crystallization (Commentary)

EC Number Crystallization (Comment) Organism
5.4.99.18 wild-type cocrystallized with 4-nitroaminoimidazole ribonucleotide and mutants H45N and H45Q soaked with 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate Escherichia coli

Protein Variants

EC Number Protein Variants Comment Organism
5.4.99.18 H45N very low catalytic activity Escherichia coli
5.4.99.18 H45Q very low catalytic activity Escherichia coli
5.4.99.18 H45W very low catalytic activity Escherichia coli

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
5.4.99.18 0.0226
-
 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate wild-type, pH 7.5, 23°C Escherichia coli

Organism

EC Number Organism UniProt Comment Textmining
5.4.99.18 Escherichia coli P0AG18
-
-

Reaction

EC Number Reaction Comment Organism Reaction ID
5.4.99.18 5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole = 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate common, buried carboxylate or CO2 binding site for substrate and product in a hydrophobic pocket, in which the carboxylate or CO2 interacts with backbone amides. The carboxylate orients the substrate for proton transfer from His45 to 5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole to form an enzyme-bound aminoimidazole ribonucleotide and CO2 intermediate. subsequent movement of the aminoimidazole moiety reorients it for addition of CO2 at C4 to generate iso-5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate. H5 is now in a position to remove a C4 proton to produce 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate Escherichia coli
a

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
5.4.99.18 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate
-
 Escherichia coli 5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole
-
 r
5.4.99.18 5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole
-
 Escherichia coli 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate
-
 r

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
5.4.99.18 0.0004
-
 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate mutant H45W, pH 7.5, 23°C Escherichia coli
5.4.99.18 0.0012
-
 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate mutant H45Q, pH 7.5, 23°C Escherichia coli
5.4.99.18 0.0021
-
 5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole mutant H45Q, pH 7.5, 23°C Escherichia coli
5.4.99.18 15.5
-
 5-carboxyamino-1-(5-phospho-D-ribosyl)imidazole wild-type, pH 7.5, 23°C Escherichia coli
5.4.99.18 15.6
-
 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxylate wild-type, pH 7.5, 23°C Escherichia coli