Application | Comment | Organism |
---|---|---|
drug development | because TgOAT possesses parasite-specific structural features as well as differing substrate specificity from its human homologue, it is an attractive target for anti-toxoplasmosis inhibitor design that can be exploited for chemotherapeutic intervention | Toxoplasma gondii |
Cloned (Comment) | Organism |
---|---|
recombinant expression of His-tagged wild-type and mutant enzymes in Escherichia coli strain BL21(DE3) Codon Plus | Toxoplasma gondii |
Protein Variants | Comment | Organism |
---|---|---|
additional information | generation of an N-terminally truncated TgOAT variant lacking the first 16 residues | Toxoplasma gondii |
V79Y | site-directed mutagenesis, the mutation in analogy to the human enzyme causes an inversion of the substrate preference with L-ornithine becoming the preferred substrate of the V79Y variant. The V79Y mutation leads to a 6fold decrease in kcat for 2-oxoglutarate which is countered by a 6fold decrease in Km, such that kcat/Km is reduced only 1.3fold | Toxoplasma gondii |
Inhibitors | Comment | Organism | Structure |
---|---|---|---|
2-oxoglutarate | substrate inhibition | Toxoplasma gondii | |
putrescine | a non-competitive inhibitor | Toxoplasma gondii | |
spermidine | a non-competitive inhibitor | Toxoplasma gondii |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
additional information | - |
additional information | steady-state and pre-steady state Michaelis-Menten kinetics, rapid-scanning stopped-flow kinetics, and transamination half-reaction kinetic parameters, overview | Toxoplasma gondii | |
0.056 | - |
2-oxoglutarate | pH 8.0, 37°C, recombinant mutant V79Y | Toxoplasma gondii | |
0.31 | - |
2-oxoglutarate | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
4.2 | - |
D-ornithine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
6.9 | - |
L-ornithine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
7.4 | - |
acetylornithine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
496 | - |
acetylornithine | pH 8.0, 37°C, recombinant mutant V79Y | Toxoplasma gondii |
Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
---|---|---|---|
77000 | - |
recombinant N-terminal deletion variant of TgOAT, gel filtration | Toxoplasma gondii |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
L-ornithine + 2-oxoglutarate | Toxoplasma gondii | - |
L-glutamate 5-semialdehyde + L-glutamate | - |
r | |
L-ornithine + 2-oxoglutarate | Toxoplasma gondii ATCC 50611 | - |
L-glutamate 5-semialdehyde + L-glutamate | - |
r | |
L-ornithine + 2-oxoglutarate | Toxoplasma gondii ME49 | - |
L-glutamate 5-semialdehyde + L-glutamate | - |
r | |
additional information | Toxoplasma gondii | the enzyme from Toxoplasma gondii does not show a specific ornithine aminotransferase activity like its human homologue, but exhibits both N-acetylornithine and gamma-aminobutyric acid (GABA) transaminase activity (EC 2.6.1.19) in vitro, suggesting a role in both arginine and GABA metabolism in vivo | ? | - |
- |
|
additional information | Toxoplasma gondii ATCC 50611 | the enzyme from Toxoplasma gondii does not show a specific ornithine aminotransferase activity like its human homologue, but exhibits both N-acetylornithine and gamma-aminobutyric acid (GABA) transaminase activity (EC 2.6.1.19) in vitro, suggesting a role in both arginine and GABA metabolism in vivo | ? | - |
- |
|
additional information | Toxoplasma gondii ME49 | the enzyme from Toxoplasma gondii does not show a specific ornithine aminotransferase activity like its human homologue, but exhibits both N-acetylornithine and gamma-aminobutyric acid (GABA) transaminase activity (EC 2.6.1.19) in vitro, suggesting a role in both arginine and GABA metabolism in vivo | ? | - |
- |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Toxoplasma gondii | S8EY38 | - |
- |
Toxoplasma gondii ATCC 50611 | S8EY38 | - |
- |
Toxoplasma gondii ME49 | S8EY38 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant His-tagged wild-type and mutant enzymes from Escherichia coli strain BL21(DE3) Codon Plus by nickel affinity chromatography and ultarfiltration | Toxoplasma gondii |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
L-ornithine + a 2-oxo carboxylate = L-glutamate 5-semialdehyde + an L-amino acid | reaction mechanism and kinetics, overview | Toxoplasma gondii |
Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
---|---|---|---|
2.6 | - |
purified recombinant His-tagged wild-type enzyme, pH 8.0, 37°C | Toxoplasma gondii |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
acetylornithine + 2-oxoglutarate | - |
Toxoplasma gondii | ? + L-glutamate | - |
r | |
acetylornithine + 2-oxoglutarate | - |
Toxoplasma gondii ATCC 50611 | ? + L-glutamate | - |
r | |
acetylornithine + 2-oxoglutarate | - |
Toxoplasma gondii ME49 | ? + L-glutamate | - |
r | |
D-ornithine + 2-oxoglutarate | - |
Toxoplasma gondii | D-glutamate 5-semialdehyde + L-glutamate | - |
r | |
D-ornithine + 2-oxoglutarate | - |
Toxoplasma gondii ATCC 50611 | D-glutamate 5-semialdehyde + L-glutamate | - |
r | |
D-ornithine + 2-oxoglutarate | - |
Toxoplasma gondii ME49 | D-glutamate 5-semialdehyde + L-glutamate | - |
r | |
L-ornithine + 2-oxoglutarate | - |
Toxoplasma gondii | L-glutamate 5-semialdehyde + L-glutamate | - |
r | |
L-ornithine + 2-oxoglutarate | - |
Toxoplasma gondii ATCC 50611 | L-glutamate 5-semialdehyde + L-glutamate | - |
r | |
L-ornithine + 2-oxoglutarate | - |
Toxoplasma gondii ME49 | L-glutamate 5-semialdehyde + L-glutamate | - |
r | |
additional information | the enzyme from Toxoplasma gondii does not show a specific ornithine aminotransferase activity like its human homologue, but exhibits both N-acetylornithine and gamma-aminobutyric acid (GABA) transaminase activity (EC 2.6.1.19) in vitro, suggesting a role in both arginine and GABA metabolism in vivo | Toxoplasma gondii | ? | - |
- |
|
additional information | the external aldimine hydrolysis is rate-limiting, and not its formation. The enzyme TgOAT also shows lyase activity with beta-chloro-L-alanine (BCA) performin g a beta-elimination reaction | Toxoplasma gondii | ? | - |
- |
|
additional information | the enzyme from Toxoplasma gondii does not show a specific ornithine aminotransferase activity like its human homologue, but exhibits both N-acetylornithine and gamma-aminobutyric acid (GABA) transaminase activity (EC 2.6.1.19) in vitro, suggesting a role in both arginine and GABA metabolism in vivo | Toxoplasma gondii ATCC 50611 | ? | - |
- |
|
additional information | the external aldimine hydrolysis is rate-limiting, and not its formation. The enzyme TgOAT also shows lyase activity with beta-chloro-L-alanine (BCA) performin g a beta-elimination reaction | Toxoplasma gondii ATCC 50611 | ? | - |
- |
|
additional information | the enzyme from Toxoplasma gondii does not show a specific ornithine aminotransferase activity like its human homologue, but exhibits both N-acetylornithine and gamma-aminobutyric acid (GABA) transaminase activity (EC 2.6.1.19) in vitro, suggesting a role in both arginine and GABA metabolism in vivo | Toxoplasma gondii ME49 | ? | - |
- |
|
additional information | the external aldimine hydrolysis is rate-limiting, and not its formation. The enzyme TgOAT also shows lyase activity with beta-chloro-L-alanine (BCA) performin g a beta-elimination reaction | Toxoplasma gondii ME49 | ? | - |
- |
Subunits | Comment | Organism |
---|---|---|
homodimer | 2 * 48000, about, SDS-PAGE | Toxoplasma gondii |
Synonyms | Comment | Organism |
---|---|---|
OAT | - |
Toxoplasma gondii |
ornithine aminotransferase | - |
Toxoplasma gondii |
TgOAT | - |
Toxoplasma gondii |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
37 | - |
assay at | Toxoplasma gondii |
Temperature Minimum [°C] | Temperature Maximum [°C] | Comment | Organism |
---|---|---|---|
15 | 75 | temperature range, profile overview | Toxoplasma gondii |
Temperature Stability Minimum [°C] | Temperature Stability Maximum [°C] | Comment | Organism |
---|---|---|---|
55 | - |
purified recombinant enzyme, pH 8.0, 10 min, stable up to | Toxoplasma gondii |
65 | - |
purified recombinant enzyme, pH 8.0, 10 min, loss of 50% activity | Toxoplasma gondii |
80 | - |
purified recombinant enzyme, pH 8.0, 10 min, inactivation | Toxoplasma gondii |
Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.41 | - |
2-oxoglutarate | pH 8.0, 37°C, recombinant mutant V79Y | Toxoplasma gondii | |
0.42 | - |
D-ornithine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
2.1 | - |
L-ornithine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
2.5 | - |
acetylornithine | pH 8.0, 37°C, recombinant mutant V79Y | Toxoplasma gondii | |
2.51 | - |
2-oxoglutarate | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
4.6 | - |
acetylornithine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
8 | - |
assay at | Toxoplasma gondii |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
pyridoxal 5'-phosphate | PLP, dependent on | Toxoplasma gondii |
Ki Value [mM] | Ki Value maximum [mM] | Inhibitor | Comment | Organism | Structure |
---|---|---|---|---|---|
17 | - |
2-oxoglutarate | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
20 | - |
2-oxoglutarate | pH 8.0, 37°C, recombinant mutant V79Y | Toxoplasma gondii | |
24 | - |
spermidine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
93 | - |
putrescine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii |
General Information | Comment | Organism |
---|---|---|
malfunction | mutation of Val79 to Tyr results in a change of substrate preference between GABA, N-acetylornithine and L-ornithine, suggesting a key role of Val79 in defining substrate specificity | Toxoplasma gondii |
additional information | the presence of Val79 in the active site of TgOAT in place of Tyr, as in its human counterpart, provides the necessary room to accommodate N-acetylornithine and GABA, resembling the active site arrangement of GABA transaminases. Contribution of active site Val79 to the specificity of the TgOAT enzym. The crystal structure of TgOAT in its internal aldimine form (PDB ID 4ZLV) is used to generate a structrue model of the V79Y mutant enzyme form, molecular modelling | Toxoplasma gondii |
physiological function | the enzyme from Toxoplasma gondii does not show a specific ornithine aminotransferase activity like its human homologue, but exhibits both N-acetylornithine and ?-aminobutyric acid (GABA) transaminase activity in vitro, suggesting a role in both arginine and GABA metabolism in vivo | Toxoplasma gondii |
kcat/KM Value [1/mMs-1] | kcat/KM Value Maximum [1/mMs-1] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.005 | - |
acetylornithine | pH 8.0, 37°C, recombinant mutant V79Y | Toxoplasma gondii | |
0.1 | - |
D-ornithine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
0.304 | - |
L-ornithine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
0.62 | - |
acetylornithine | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii | |
7.321 | - |
2-oxoglutarate | pH 8.0, 37°C, recombinant mutant V79Y | Toxoplasma gondii | |
8.097 | - |
2-oxoglutarate | pH 8.0, 37°C, recombinant wild-type enzyme | Toxoplasma gondii |