| Origin | microorganism |
|---|---|
| Lineage name | L-Glutamate : ammonia ligase (ADP-forming) |
| EC Number | 6.3.1.2 |
| Reaction formula | ATP + L-Glutamate + NH3→→→ ADP + Orthophosphate + L-Glutamine |
Glutamine Synthetase (GST)
- The enzyme is useful for the determination of ammonia and ATP in clinical analysis.
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SPECIFICATION
| Appearance | light yellow lyophilizate | |
|---|---|---|
| Activity | ≧7 U/mg lyophilizate | |
| Contaminants | catalase ≦0.5％ | |
| Stabilizer | sucrose | |
| Storage | below-20℃ |
PROPERTIES
| Molecular weight | ca. 900 kDa (gel filtration) |
|---|---|
| Structure | 57 kDa (SDS-PAGE) |
| Isoelectric point | 6.5 |
| Michaelis constant | 1.5×10-2M (L-glutamate) |
| 1.3×10-4M (ammonia) | |
| 8.7×10-4M (ATP) | |
| pH Optimum | 7.0 |
| pH Stability | 6.5–9.5 |
| Optimum temperature | 60℃ |
| Thermal stability | below 40℃ |
| Stability (liquid form) | stable at 20℃ for at least two weeks |
| Stability (powder form) | stable at 37℃ for at least one month |
| Inhibitors | methionine sulfoximine, carbamyl phosphate |
| Activators | Mg2+，Mn2+ |
| Specificity | L-glutamate (100), D-glutamate (0.8) |
| NH₃(100), NH₂OH (12) | |
| ATP (100), GTP (2.5) |
APPLICATIONS
The enzyme is useful for the determination of ammonia and ATP in clinical analysis.
REFERENCES
Ebner, E. et al., “Methods in Enzymology,” Vol. 17A, Academic Press, New York, 1970, pp. 910–922.
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