Involved in the hydrocarbon hydroxylating system, which transfers electrons from NADH to rubredoxin reductase and then through rubredoxin to alkane 1 monooxygenase. H(+) + NAD(+) + 2 reduced [rubredoxin] = NADH + 2 oxidized [rubredoxin] Hydrocarbon metabolism; alkane degradation. Homodimer. Constitutively expressed. Belongs to the FAD-dependent oxidoreductase family.