Purification and characterization of NADPH-ferredoxin reductase from bovine kidney mitochondria

An NADPH-ferredoxin reductase (EC 1.6.7.1) was purified from bovine kidney mitochondria and its physicochemical properties were investigated. The ratio of the absorbances at 272 and 450 nm was 8.8, and the enzyme had a specific activity of 5,850 nmol/min/mg for the reduction of cytochrome c. We determined the molecular weights of the NADPH-ferredoxin reductase as 53,000 and 34,000 Da by SDS-PAGE and HPLC analysis, respectively. Renal ferredoxin was substituted by adreno-ferredoxin, but spinach ferredoxin was not. The reductase formed an immuno-precipitin line against antibody of the adrenal reductase on Ouchterlony double-diffusion analysis. The sequences of amino acid residues of this reductase in the amino-terminal regions were identical. The amino-terminal region of the reductase may thus play an essential role in the enzymatic function.