TABLE 4.
Apparent Km and kcat values of purified C. thermocellum wild-type and LL350 AdhE proteins
| C. thermocellum straina (characteristic) and enzyme | Substrate | Km (mM) | kcat (S−1) | kcat/Km (S−1 M−1) |
|---|---|---|---|---|
| LL1004 (wild type) | ||||
| ALDH | Acetyl-CoA | 0.0084 ± 0.0002e | 280 ± 2 | 3.3E + 07 |
| NADH | 0.052 ± 0.003 | 150 ± 3 | 3.0E + 06 | |
| ADH | Acetaldehyde | 1.6 ± 0.05 | 240 ± 4 | 1.5E + 05 |
| NADH | 0.088 ± 0.006 | 240 ± 6 | 2.7E + 06 | |
| LL350 (moderate ethanol production) | ||||
| ALDH | Acetyl-CoA | 0.0042 ± 0.0004d | 230 ± 2f | 5.4E + 07 |
| NADH | 0.026 ± 0.0002d | 62 ± 0.1f | 2.4E + 06d | |
| ADH | Acetaldehydeb | 1.4 ± 0.05 | 220 ± 2d | 1.5E + 05 |
| Acetaldehydec | 1.4 ± 0.04 | 210 ± 3d | 1.5E + 05 | |
| NADH | 0.17 ± 0.01d | 220 ± 5 | 1.3E + 06d | |
| NADPH | 0.075 ± 0.01 | 280 ± 7 | 3.7E + 06 |
a
Source of AdhE, which was expressed in E. coli and affinity purified.
b
Measurements were done with NADH as a cofactor.
c
Measurements were done with NADPH as a cofactor.
d
Compared to value obtained with wild-type AdhE, two-tailed P value of <0.05.
e
Error represents 1 standard error, at a confidence level of 0.95 (n = 10 to 16, depending on the sample).
f
Compared to value obtained with wild-type AdhE, two-tailed P value of <0.01.