Cloned (Comment) | Organism |
---|---|
recombinant enzyme expression in Escherichia coli strain BL21(DE3)pLysS | Homo sapiens |
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 | 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 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 | 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 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 | 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 | UniProt | Comment | Textmining |
---|---|---|---|
Homo sapiens | P04181 | - |
- |
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 Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
---|---|---|---|
22 | - |
purified recombinant enzyme, pH 8.0, 25°C | Homo sapiens |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
L-ornithine + 2-oxoglutarate | - |
Homo sapiens | L-glutamate 5-semialdehyde + L-glutamate | - |
r |
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 | Comment | Organism |
---|---|---|
hOAT | - |
Homo sapiens |
ornithine delta-aminotransferase | - |
Homo sapiens |
ornithine: 2-oxo-glutarate aminotransferase | - |
Homo sapiens |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | - |
assay at | Homo sapiens |
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 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 Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
8 | - |
assay at | Homo sapiens |
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 | 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 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 |