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Literature summary extracted from

  • Menon, B.R.; Menon, N.; Fisher, K.; Rigby, S.E.; Leys, D.; Scrutton, N.S.
    Glutamate 338 is an electrostatic facilitator of C-Co bond breakage in a dynamic/electrostatic model of catalysis by ornithine aminomutase (2015), FEBS J., 282, 1242-1255 .
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

EC Number Cloned (Comment) Organism
5.4.3.5 genes oraS and oraE encoding the alpha- and beta-subunit, recombinant expression of wild-type and beta-subunit mutant enzymes Acetoanaerobium sticklandii

Protein Variants

EC Number Protein Variants Comment Organism
5.4.3.5 E338A site-directed mutagenesis, the beta-subunit mutant shows a reduced turnover number compared to wild-type enzyme, while the Km value is similar Acetoanaerobium sticklandii
5.4.3.5 E338D site-directed mutagenesis, the beta-subunit mutant shows a reduced turnover number compared to wild-type enzyme, while the Km value is similar Acetoanaerobium sticklandii
5.4.3.5 E338Q site-directed mutagenesis, the beta-subunit mutant shows a reduced turnover number compared to wild-type enzyme, while the Km value is similar Acetoanaerobium sticklandii
5.4.3.5 additional information analysis of substrate-bound wild-type and beta-subunit mutant enzymes, overview Acetoanaerobium sticklandii

Inhibitors

EC Number Inhibitors Comment Organism Structure
5.4.3.5 DL-2,4-diaminobutyric acid DAB, a competitive inhibitor Acetoanaerobium sticklandii

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
5.4.3.5 additional information
-
 additional information steady-state kinetics of wild-type enzyme and beta-subunit mutants, enzyme dynamics and C-Co bond homolysis in single-turnover stopped-flow kinetics Acetoanaerobium sticklandii

Organism

EC Number Organism UniProt Comment Textmining
5.4.3.5 Acetoanaerobium sticklandii E3PY95 AND E3PY96 subunits beta and alpha
-

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
5.4.3.5 D-ornithine
-
 Acetoanaerobium sticklandii (2R,4S)-2,4-diaminopentanoate
-
 r

Synonyms

EC Number Synonyms Comment Organism
5.4.3.5 OAM
-
 Acetoanaerobium sticklandii
5.4.3.5 ornithine 4,5-aminomutase
-
 Acetoanaerobium sticklandii
5.4.3.5 ornithine aminomutase
-
 Acetoanaerobium sticklandii

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
5.4.3.5 25
-
 assay at Acetoanaerobium sticklandii

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
5.4.3.5 564
-
 D-ornithine recombinant beta-subunit mutant E338A, pH 8.5, 25°C Acetoanaerobium sticklandii
5.4.3.5 608
-
 D-ornithine recombinant beta-subunit mutant E338D, pH 8.5, 25°C Acetoanaerobium sticklandii
5.4.3.5 694
-
 D-ornithine recombinant beta-subunit mutant E338Q, pH 8.5, 25°C Acetoanaerobium sticklandii
5.4.3.5 1072
-
 D-ornithine recombinant wild-type enzyme, pH 8.5, 25°C Acetoanaerobium sticklandii

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
5.4.3.5 8.5
-
 assay at Acetoanaerobium sticklandii

General Information

EC Number General Information Comment Organism
5.4.3.5 malfunction substrate-induced C-Co bond homolysis is compromised in Glu388 variant forms of OAM, although photolysis of the C-Co bond is not affected by the identity of residue 338. Electrostatic interactions of Glu338 with the 5'-deoxyadenosyl group of B12 potentiate C-Co bond homolysis in closed conformations only. These conformations are unlocked by substrate binding. Conformational sampling of the mobile cobalamin-binding domain occurs in the Glu388 variants, but that, in adopting the closed conformation, C-Co bond homolysis is compromised. The population of the closed conformation has an associated lifetime. Each time the closed conformation is populated, there is a higher probability of bond homolysis in wild-type OAM relative to the variant forms because of the electrostatic interactions formed between Glu338 and the cobalamin cofactor that facilitate bond homolysis Acetoanaerobium sticklandii
5.4.3.5 additional information for the pyridoxal 5'-phosphate and cobalamin-dependent enzyme ornithine 4,5-aminomutase, large-scale re-orientation of the cobalamin-binding domain linked to C-Co bond breakage is proposed. In the model, substrate binding triggers dynamic sampling of the B12-binding Rossmann domain to achieve a catalytically competent closed conformational state. In closed conformations of the enzyme, Glu338 is thought to facilitate C-Co bond breakage by close association with the cobalamin adenosyl group. Large-scale motion is required to pre-organize the active site by enabling transient formation of closed conformations of OAM. In closed conformations, Glu338 interacts with the 5'-deoxyadenosyl group of cobalamin. This interaction is required to potentiate C-Co homolysis, and is a crucial component of the approximately 1012 rate enhancement achieved by cobalamin-dependent enzymes for C-Co bond homolysis. Three-dimensional enzyme structure and active site structure analysis, spectral analysis of substrate-bound wild-type and beta-subunit mutant enzymes, overview Acetoanaerobium sticklandii