Any feedback?
Please rate this page
(literature.php)
(0/150)

BRENDA support

Literature summary for 2.6.1.13 extracted from

  • Montioli, R.; Zamparelli, C.; Borri Voltattorni, C.; Cellini, B.
    Oligomeric state and thermal stability of apo- and holo-human ornithine delta-aminotransferase (2017), Protein J., 36, 174-185 .
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

Cloned (Comment) Organism
recombinant enzyme expression in Escherichia coli strain BL21(DE3)pLysS Homo sapiens

Protein Variants

Protein Variants Comment Organism
R217A site-directed mutagenesis, the artificial dimeric mutant variant exhibits spectroscopic properties, Tm values, and catalytic features similar to those of the tetrameric species. The mutant shows increased activity compared to wild-type Homo sapiens

General Stability

General Stability Organism
unlike holo-hOAT, apo-hOAT is prone to unfolding and aggregation under physiological conditions. Under physiological conditions the apo-tetramer is slightly less prone to unfolding and aggregation than the apo-dimer Homo sapiens

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
additional information
-
additional information Michaelis-Menten steady-state kinetics Homo sapiens
2.4
-
2-oxoglutarate pH 8.0, 25°C, recombinant mutant R217A, 60 nM enzyme Homo sapiens
3.9
-
2-oxoglutarate pH 8.0, 25°C, recombinant wild-type enzyme, 60 nM enzyme Homo sapiens
4
-
2-oxoglutarate pH 8.0, 15°C, recombinant wild-ype enzyme, 0.001 mM enzyme Homo sapiens
4.4
-
2-oxoglutarate pH 8.0, 15°C, recombinant mutant R217A, 0.001 mM enzyme Homo sapiens
5.1
-
L-ornithine pH 8.0, 25°C, recombinant mutant R217A, 60 nM enzyme Homo sapiens
6.5
-
L-ornithine pH 8.0, 25°C, recombinant wild-type enzyme, 60 nM enzyme Homo sapiens
6.9
-
L-ornithine pH 8.0, 15°C, recombinant mutant R217A, 0.001 mM enzyme Homo sapiens
7
-
L-ornithine pH 8.0, 15°C, recombinant wild-type enzyme, 0.001 mM enzyme Homo sapiens

Localization

Localization Comment Organism GeneOntology No. Textmining
mitochondrion
-
Homo sapiens 5739
-
additional information OAT is synthesized as a 49 kDa precursor in the cytosol and it is then imported into mitochondria where it reaches the functional conformation upon removal of an N-terminal mitochondrial targeting sequence (residues 1-25) producing a about 45 kDa mature protein Homo sapiens
-
-

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
88000
-
recombinant dimeric mutant R217A, gel filtration and analytical ultracentrifugation sedimentation analysis Homo sapiens
182000 183000 recombinant tetrameric wild-type enzyme, gel filtration and analytical ultracentrifugation sedimentation analysis Homo sapiens

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
L-ornithine + 2-oxoglutarate Homo sapiens
-
L-glutamate 5-semialdehyde + L-glutamate
-
r

Organism

Organism UniProt Comment Textmining
Homo sapiens P04181
-
-

Purification (Commentary)

Purification (Comment) Organism
recombinant enzyme 9.6fold from Escherichia coli strain BL21(DE3)pLysS by anion exchange chromatography, ultrafiltration, and gel filtration, followed by another step of ultrafiltration Homo sapiens

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
22
-
purified recombinant enzyme, pH 8.0, 25°C Homo sapiens

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
L-ornithine + 2-oxoglutarate
-
Homo sapiens L-glutamate 5-semialdehyde + L-glutamate
-
r

Subunits

Subunits Comment Organism
More apo and holo-hOAT enzymes (a) show a similar tertiary structure, even if apo displays a more pronounced exposure of hydrophobic patches, and (b) exhibit a tetrameric structure with a tetramer-dimer equilibrium dissociation constant about fivefold higher for the apoform with respect to the holoform. The catalytic unit of hOAT is the dimer. Enzyme residue Arg217 is an important hot-spot at the dimer-dimer interface of hOAT. The catalytic unit of hOAT is the dimer. The far-UV CD spectrum of the enzyme gives a secondary structure composition of 37% alpha-helix, 18% beta-sheet and 45% random coil, values identical to those calculated from the solved crystal structure, quaternary structure analysis, overview Homo sapiens
tetramer 4 * 45000, mature enzyme, SDS-PAGE, 4 * 49000, pro-enzyme, SDS-PAGE, dimer of dimers Homo sapiens

Synonyms

Synonyms Comment Organism
hOAT
-
Homo sapiens
ornithine delta-aminotransferase
-
Homo sapiens
ornithine: 2-oxo-glutarate aminotransferase
-
Homo sapiens

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
25
-
assay at Homo sapiens

Temperature Stability [°C]

Temperature Stability Minimum [°C] Temperature Stability Maximum [°C] Comment Organism
46
-
Tm of the apo-hOAT enzyme Homo sapiens
67
-
Tm of the holo-hOAT enzyme Homo sapiens

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
20
-
2-oxoglutarate pH 8.0, 15°C, recombinant wild-ype enzyme, 0.001 mM enzyme Homo sapiens
20.7
-
2-oxoglutarate pH 8.0, 15°C, recombinant mutant R217A, 0.001 mM enzyme Homo sapiens
20.7
-
L-ornithine pH 8.0, 15°C, recombinant mutant R217A, 0.001 mM enzyme Homo sapiens
22.6
-
L-ornithine pH 8.0, 15°C, recombinant wild-type enzyme, 0.001 mM enzyme Homo sapiens
34.9
-
L-ornithine pH 8.0, 25°C, recombinant wild-type enzyme, 60 nM enzyme Homo sapiens
35.7
-
2-oxoglutarate pH 8.0, 25°C, recombinant wild-ype enzyme, 60 nM enzyme Homo sapiens
38.1
-
2-oxoglutarate pH 8.0, 25°C, recombinant mutant R217A, 60 nM enzyme Homo sapiens
38.4
-
L-ornithine pH 8.0, 25°C, recombinant mutant R217A, 60 nM enzyme Homo sapiens

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
8
-
assay at Homo sapiens

Cofactor

Cofactor Comment Organism Structure
pyridoxal 5'-phosphate PLP, dependent on, purified hOAT bind about 2 moles of PLP/mol of enzyme dimer Homo sapiens

General Information

General Information Comment Organism
malfunction a deficit in ornithine aminotransferase (OAT) is associated with gyrate atrophy, a rare autosomal recessive disorder causing progressive blindness and chorioretinal degeneration Homo sapiens
physiological function ornithine delta-aminotransferase (OAT) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the delta-transamination of L-ornithine and 2-oxoglutarate to glutamic-gamma-semialdehyde (GSA) and L-glutamate in the mitochondrial matrix. GSA then spontaneously cyclizes forming pirroline-5-carboxylate (P5C), a proline precursor Homo sapiens

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
3
-
L-ornithine pH 8.0, 15°C, recombinant mutant R217A, 0.001 mM enzyme Homo sapiens
3.2
-
L-ornithine pH 8.0, 15°C, recombinant wild-type enzyme, 0.001 mM enzyme Homo sapiens
4.7
-
2-oxoglutarate pH 8.0, 15°C, recombinant mutant R217A, 0.001 mM enzyme Homo sapiens
5
-
2-oxoglutarate pH 8.0, 15°C, recombinant wild-ype enzyme, 0.001 mM enzyme Homo sapiens
5.4
-
L-ornithine pH 8.0, 25°C, recombinant wild-type enzyme Homo sapiens
7.5
-
L-ornithine pH 8.0, 25°C, recombinant mutant R217A Homo sapiens
9.2
-
2-oxoglutarate pH 8.0, 25°C, recombinant wild-type enzyme Homo sapiens
15.9
-
2-oxoglutarate pH 8.0, 25°C, recombinant mutant R217A Homo sapiens