Table IV. Specific activities of hydrogenase and nitrate reductase in cell extracts of G. metallireducens.
Activity was determined spectrophotometrically using reduced benzyl viologen as electron donor (nitrate reductase) or the oxidized form as electron acceptor (hydrogenase). For the succinate dehydrogenase control, ferricenium was used as electron acceptor. One milliunit is referred to as conversion of 1 nmol min−1 H2/nitrate/succinate, respectively. Mean values ± S.D. from three independent determinations are presented.
| Enzyme | Extracts |
-Fold increase benzoate/acetate (membrane fraction) | |||
|---|---|---|---|---|---|
| Benzoate-grown cells |
Acetate-grown cells |
||||
| Soluble | Membrane | Soluble | Membrane | ||
| milliunits mg−1 | |||||
| Hydrogenase | 47 ± 5 | 157 ± 12 | 10 ± 4 | 10 ± 2 | 16 |
| Nitrate reductase | 146 ± 8 | 450 ± 50 | 48 ± 12 | 125 ± 20 | 4 |
| Succinate dehydrogenase (control) | 155 ± 40 | 525 ± 70 | 270 ± 50 | 774 ± 200 | 0.7 |