TABLE 1.
Specific activities of citric acid cycle enzymes and other enzymes in cells grown on various media
| Enzyme | EC no. | Sp act (nmol min−1 mg−1) on the following growth mediaa:
|
||
|---|---|---|---|---|
| H2 + CO2 | H2 + acetate + yeast extract | Tryptone + yeast extract | ||
| Citric acid cycle enzymes | ||||
| Citrate synthase | 2.3.3.1 | 101 ± 21 | 137 ± 31 | 217 ± 60c |
| Aconitate hydratase | 4.2.1.3 | 342 ± 72 | 221 ± 28 | 525 ± 140 |
| Isocitrate dehydrogenase | 1.1.1.42 | 430 ± 34 | 626 ± 87 | 711 ± 224 |
| 2-Oxoglutarate synthase | 1.2.7.3 | 112 ± 23 | 148 ± 12 | 130 ± 17 |
| Succinate:CoA ligase (ADP forming) | 6.2.1.5 | 99 ± 16 | 90 ± 1 | 90 ± 11 |
| Succinate dehydrogenase | 1.3.99.1 | 192 ± 41 | 115 ± 8 | 161 ± 88 |
| Succinate dehydrogenaseb | 1.3.99.1 | 195 ± 77 | 148 ± 109 | 201 ± 76 |
| Fumarate hydratase | 4.2.1.2 | 316 ± 10 | 339 ± 96 | 428 ± 52 |
| Malate dehydrogenase | 1.1.1.37 | 1,176 ± 193 | 1,747 ± 646 | 2,221 ± 118 |
| Other enzymes | ||||
| Citrate lyase | 4.1.3.6 | 25 ± 6 | 9 ± 3 | 3 ± 0 |
| ATP citrate synthase | 2.3.3.8 | 12 ± 16 | 51 ± 8 | 25 ± 3 |
| Acetate:CoA ligase (ADP forming) | 6.2.1.13 | 0 | 0 | 93 ± 6 |
| Acetate:CoA ligase (AMP forming) | 6.2.1.1 | 95 ± 8 | 32 ± 6 | 0 |
| Pyruvate synthase | 1.2.7.1 | 0 | 0 | 59 ± 19 |
| Pyruvate-water dikinase | 2.7.9.2 | 32 ± 5 | 19 ± 4 | 22 ± 5 |
| Phosphoenolpyruvate carboxylase | 4.1.1.31 | 123 ± 20 | 126 ± 2 | 0 |
| Malate dehydrogenase (decarboxylating) | 1.1.1.39 | 319 ± 49 | 293 ± 33 | 558 ± 76 |
| Hydrogenase | 1.12.7.2 | 165 ± 20 | 130 ± 11 | 210 ± 34 |
| Hydrogenaseb | 1.12.7.2 | 474 ± 110 | 1,005 ± 80 | 520 ± 65 |
| Formate dehydrogenase | 1.2.2.- | 299 ± 199 | 245 ± 160 | 524 ± 200 |
| Formate dehydrogenaseb | 1.2.2.- | 2,818 ± 1,674 | 1,842 ± 1,253 | 5,743 ± 152 |
| Malate synthase | 2.3.3.9 | 19 ± 12 | 30 ± 7 | 21 ± 9 |
Most enzyme activities were measured using only the cytoplasmic protein fraction. The exceptions were the succinate dehydrogenase, hydrogenase, and formate dehydrogenase activities, which were also measured using whole-cell extracts. The values are means ± standard deviations.
Enzyme activity measured using the whole-cell extract.
Boldface type indicates values that are significantly different (P < 0.05) from one or both values for the same enzyme that are not in boldface type. The statistical trends are as follows: for citrate synthase, peptides > H2-CO2; for aconitate hydratase, peptides > acetate; for malate dehydrogenase, peptides > H2-CO2; for citrate lyase, H2-CO2 > acetate and peptides; for ATP citrate synthase, acetate > peptides and H2-CO2; for acetate:CoA ligase (ADP forming), peptides > acetate and H2-CO2; for acetate:CoA ligase (AMP forming), H2-CO2 > acetate > peptides; for pyruvate synthase, peptides > acetate and H2-CO2; for phosphoenolpyruvate carboxylase, acetate and H2-CO2 > peptides; for malate dehydrogenase (decarboxylating), peptides > acetate and H2-CO2; and for hydrogenase in whole-cell extracts, acetate > peptides and H2-CO2.