A selC mutant is devoid of the hydrogenase-independent H
: BV oxidoreductase activity. Extracts derived from MC4100 (lane 1) and the isogenic ΔselC mutant FM460 (lane 2) were separated by non-denaturing PAGE and subsequently stained for hydrogenase enzyme activity. Equivalent amounts of Triton X-100-treated crude extract (50 μg of protein) were applied to each lane. The activity bands corresponding to Hyd-1 and Hyd-2 are indicated, as is the activity band due to Fdh-N/Fdh-O (designated by an arrow).