Table 3. Results of transaminase-catalysed amination reactions of pyruvate, α-ketoglutarate, glyoxylic acid, α-keto-γ-(methylthio)-butyrate and phenylpyruvate with rac-1-phenylethylamine, propan-2-amine, rac-butan-2-amine, cyclohexylamine and dl-alanine after 24 h at 30 °C.
| Protein | Amino donor | Pyruvate c [%]a | α-Keto- glutarate c [%]b | Glyoxylic acid c [%] | α-Keto-γ-(methyl-thio)-butyrate c [%]b | Phenyl-pyruvate c [%]b |
|---|---|---|---|---|---|---|
| CpuTA1 | 1-phenylethylamine | 40 | 29 | 21 | 23 | 4 |
| propan-2-amine | 2 | 1 | — | — | — | |
| butan-2-amine | 3 | 1 | — | — | — | |
| cyclohexylamine | 1 | 1 | — | — | — | |
| dl-alanine | — | 56 | 71 | 72 | 67 | |
| MgiTA1 | 1-phenylethylamine | 79 | 74 | 39 | 27 | 2 |
| propan-2-amine | 2 | 1 | — | — | — | |
| butan-2-amine | 2 | 2 | — | — | — | |
| cyclohexylamine | 1 | <1 | — | — | — | |
| dl-alanine | — | 43 | 91 | 59 | 16 | |
| RaqTA3 | 1-phenylethylamine | 24 | 1 | 4 | 4 | 2 |
| propan-2-amine | 2 | <1 | — | — | — | |
| butan-2-amine | 2 | <1 | — | — | — | |
| cyclohexylamine | 1 | <1 | — | — | — | |
| dl-alanine | — | 63 | 12 | 17 | 0 |
Reaction conditions: cell-free E. coli lysate containing different TAs (2.0 mg mL−1 total lysate protein), 200 mM rac-1-phenylethylamine, rac-butan-2-amine or dl-alanine, or 100 mM propan-2-amine or cyclohexylamine, 20 mM pyruvate, α-ketoglutarate, glyoxylic acid, α-keto-γ-(methylthio)-butyrate or phenylpyruvate, 0.1 mM PLP and 100 mM KPi buffer, pH 7.5, 24 h at 30 °C. The conversions were determined by rp-HPLC after derivatisation of the amino acid products with Marfey’s reagent; a: Calculated from the sum of d-Ala und l-Ala for following reason: in case of Ala, substantial racemisation of the initially formed d-Ala by an amino acid racemase present in the cell-free E. coli lysates occurred as checked by incubation of 20 mM d-Ala in the presence of enzyme lysate and PLP at the same concentrations. 34% of l-Ala was formed in the presence of lysate from CpuTA1, respectively MgiTA1 under these conditions. b: Calculated from the amount of d-Glu, d-Met or d-Phe formed as racemisation to the corresponding l-amino acids was found negligible.