PURIFICATION OF NADH-CYTOCHROME B(5) REDUCTASE FROM RAT-LIVER PLASMA-MEMBRANES

An NADH-cytochrome b(5) reductase was purified from rat liver plasma m embranes. Rat liver plasma membranes were prepared by aqueous two-phas e partition. Peripheral proteins were removed by EDTA extraction and i ntegral membrane proteins were solubilized with Triton X-100. The NADH -cytochrome b(5) reductase was purified by hydroxyapatite, anion excha nge, and gel filtration chromatographies. The purified preparation was homogeneous and estimated to have an apparent molecular weight of 32 kDa on SDS-polyacrylamide gel electrophoresis. Two tryptic peptides of the purified enzyme had sequence homologies with rat, human, and bovi ne NADH-cytochrome bs reductases.