TABLE 2.
AST pathway enzymes in E. coli and K. aerogenes
| Line | Strain | Mediuma | Enzyme activity, μmol/h/mg of protein (n)b, of:
|
||
|---|---|---|---|---|---|
| Dihydrolase | Desuccinylase | Transaminasec | |||
| E. coli | |||||
| 1 | Wild type | Glucose-arginine | 1.5 ± 0.16 (3) | 2.6 ± 0.10 (3) | 5.4 ± 0.24 (3) |
| 2 | Wild type | Glucose-NH4+-arginine | 0.06 ± 0.033 (2) | 0.09 ± 0.033 (2) | 0.57 ± 0.35 (2) |
| 3 | Wild type | Glucose-glutamine | 0.47 ± 0.04 (4) | 0.84 ± 0.03 (4) | 3.8 ± 0.36 (4) |
| 4 | Wild type | Glucose-NH4+-glutamine | 0.08 ± 0.08 (3) | <0.05 (3) | 2.4 ± 0.14 (3) |
| 5 | glnG | Glucose-glutamine | 0.14 ± 0.03 (4) | 0.22 ± 0.03 (4) | 2.2 ± 0.11 (4) |
| K. aerogenes | |||||
| 6 | Wild type | Arginine | 38 ± 4.0 (2) | 21 ± 0.6 (2) | 64 ± 5.6 (2) |
| 7 | Wild type | Glucose-arginine | 8.0 ± 0.31 (5) | 8.1 ± 0.42 (5) | 24 ± 1.1 (5) |
| 8 | Wild type | Glucose-NH4+-arginine | 3.63 ± 0.20 (3) | 3.32 ± 0.34 (3) | 9.32 ± 0.56 (3) |
| 9 | Wild type | Glucose-glutamine | 0.48 ± 0.058 (2) | 0.44 ± 0.091 (2) | 1.6 ± 0.1 (2) |
| 10 | Wild type | Glucose-NH4+-glutamine | 0.14 ± 0.03 (3) | 0.22 ± 0.033 (3) | 1.2 ± 0.18 (3) |
| 11 | glnG | Glucose-glutamine | 0.17 ± 0.029 (2) | 0.05 ± 0.05 (2) | 7.5 ± 1.1 (2) |
| 12 | glnG | Glucose-arginine | 7.41 ± 0.88 (2) | 6.86 ± 1.3 (2) | 18 ± 1.6 (2) |
a
Cells were grown in minimal medium with 0.4% glucose and 0.2% of the indicated nitrogen sources. Arginine was at 1% when used as both carbon and nitrogen source.
b
The variation is expressed as the standard error of the mean, with the number of determinations in parentheses.
c
Except for cells grown in arginine-containing medium, the assay for this enzyme measures both the arginine-repressible acetylornithine transaminase and the arginine-inducible succinylornithine transaminase.