Figure 2. Hydrogenases 1 and 2 are inactive in iscA and erpA mutants.

Aliquots of crude extracts (25 µg protein) derived from the bacterial stains shown were separated by non-denaturing PAGE (7.5% w/v polacrylamide) and subsequently stained for hydrogenase enzyme activity. Hydrogenase 1 migrates as a single active enzyme species while hydrogenase 2 shows multiple active forms, which are designated on the right of the panel. The weak hydrogen: benzyl viologen oxidoreductase activity that is independent of the [NiFe]-hydrogenases, and which is associated with formate dehydrogenase [25], is also designated.