A phospholipid-dependent NADH-coenzyme Q reductase from liver plasma membrane.

A 34 kDa coenzyme Q reductase has been solubilized and purified from pig liver plasma membranes. The solubilized enzyme reduced coenzyme Q0 with NADH. Ubiquinones with longer isoprenoid side chain such as Q2 and Q10 were also reduced when the quinones and the enzyme were reconstituted into phospholipid liposomes. N-terminal sequencing of an internal peptide showed identity to bovine NADH-cytochrome b5 reductase. Biochemical characterization of the purified enzyme indicated that the coenzyme Q reductase corresponds to an unusual form of NADH-cytochrome b5 reductase.