Cloned (Comment) | Organism |
---|---|
gene gadB, recombinant expression in Escherichia coli strain BL21(DE3) | Escherichia coli |
Protein Variants | Comment | Organism |
---|---|---|
additional information | cross-linked aggregation method is used in order to extend the active range of GAD toward alkaline pH. Cross-linked aggregation activate GAD even at neutral and alkaline pH values. It is a useful method capable of facilitating recovery and reuse of the enzyme as well as increasing the reaction conversion by extending the active pH range of GAD. GAD from Escherichia coli is prepared as cross-linked enzyme aggregate (CLEA) in which the enzyme is precipitated using ammonium sulfate (60% saturation) and then cross-linked with glutaraldehyde (2%) in sodium acetate buffer (0.2 mol/l, pH 4.6). The cross-linked aggregation extends an active pH-range of GAD from pH 5.5 up to pH 8.0. As a result, the reaction conversion of 1 mol/l monosodium L-glutamate into GABA is improved from 13% to 22%. Moreover, the CLEA of GAD is easily recovered after the reaction and reused retaining over 95% of its initial activity during the first four cycles and over 60% activity at the 10th cycle. Method evaluation and optimization, overview | Escherichia coli |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
L-glutamate | Escherichia coli | - |
4-aminobutanoate + CO2 | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Escherichia coli | P69910 | - |
- |
Purification (Comment) | Organism |
---|---|
recombinant enzyme from Escherichia coli strain BL21(DE3) partially by ammonium sulfate fractionation | Escherichia coli |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
L-glutamate | - |
Escherichia coli | 4-aminobutanoate + CO2 | - |
? | |
L-glutamate | alpha-decarboxylation | Escherichia coli | 4-aminobutanoate + CO2 | - |
? |
Synonyms | Comment | Organism |
---|---|---|
GAD | - |
Escherichia coli |
GadB | - |
Escherichia coli |
GADbeta | - |
Escherichia coli |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
37 | - |
assay at | Escherichia coli |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
4.6 | - |
assay at | Escherichia coli |
pH Minimum | pH Maximum | Comment | Organism |
---|---|---|---|
additional information | - |
pH rise caused by the reaction inactivates the enzyme catalyst, which is active only under acidic conditions, and consequently leads to low reaction conversions | Escherichia coli |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
pyridoxal 5'-phosphate | dependent on | Escherichia coli |
General Information | Comment | Organism |
---|---|---|
additional information | pH rise caused by the reaction inactivates the enzyme catalyst, which is active only under acidic conditions, and consequently leads to low reaction conversions. Cross-linked aggregation method is used in order to extend the active range of GAD toward alkaline pH | Escherichia coli |