Table 4.
Effect of varied activity ratio for CtXR and CbFDH during whole cell-catalyzed reduction of 100 mM ethyl 4-cyanobenzoylformate by a suitable mixture of E. coli XR_FDH and E. coli FDH.
| substrate conc. [mM] | XR : FDH | additive1,2 | yield [mM]3/ee [%]4 |
| 100 | 1 : 2 | polymyxin B | 18/86.1 R |
| 100 | 1 : 6 | polymyxin B | 36/74.6 R |
| 100 | 1 : 20 | polymyxin B | 62/71.3 R |
| 100 | 1 : 2 | NAD+, polymyxin B | 23/66.8 R |
| 100 | 1 : 6 | NAD+, polymyxin B | 36/64.7 R |
| 100 | 1 : 20 | NAD+, polymyxin B | 64/71.2 R |
| 500 | 1 : 2 | polymyxin B | 25/≥ 99.9 R |
| 500 | 1 : 6 | polymyxin B | 39/84.6 R |
| 500 | 1 : 20 | polymyxin B | 88/73.7 R |
| 500 | 1 : 2 | NAD+, polymyxin B | 29/≥ 99.9 R |
| 500 | 1 : 6 | NAD+, polymyxin B | 42/85.1 R |
| 500 | 1 : 20 | NAD+, polymyxin B | 90/75.5 R |
The activity of CtXR was kept constant at 1.4 U/mL throughout.
1 [NAD+] = 490 μM, 2 [polymyxin B sulphate] = 144 μM;3Standard errors ≤ 15%. 4Detection limit of ethyl 4-cyanomandelate is below 0.01 mM.