Hyd-3 activity is detectable after electrophoresis in different gel-systems. The strains CP971 (ΔhycA-I), CPD17 (ΔhyaB hybC fdhE), CPD23 (ΔhyaB hybC fdhE fdhF) and MC4100 were grown anaerobically in TGYEP, pH 6.5. A: About 25 μg of total protein were applied to a Tris-barbitone gel system, pH 7.0 (7.5% w/v polyacrylamide) and the gel was stained in 100% hydrogen with BV/TTC after electrophoresis. B: Extracts of the given strains were separated into soluble fraction (SF) and membrane fraction (MF) by ultracentrifugation and 25 μg of each fraction were applied to native PAGE (7.5% w/v polyacrylamide in Tris/glycine system). On the right hand side of the figures the top of the gel is marked with an arrow and the migration patterns of hydrogenase 1 (Hyd-1), Hyd-2 and Hyd-3 are indicated.