Purification and Properties of the Tightly Bound Reduced Nicotinamide Adenine Dinucleotide Phosphate-Adrenodoxin Reductase of Bovine Adrenocortical Mitochondria1

Two forms of NADPH-adrenodoxin reductase, tightly and loosely bound forms, were found in bovine adrenocortical mitochondria. The loosely bound NADPH-adrenodoxin reductase was solubilized by ultrasonication and its content was about 65% of the total activity in bovine adrenocortical mitochondria. The tightly bound NADPH-adrenodoxin reductase could not be solubilized by mechanical sonication and required detergent treatment. The tightly bound NADPH-adrenodoxin reductase was purified to homogeneity, judging by sodium dodecyl sulfate (SDS) gel electrophoresis, from bovine adrenocortical mitochondria using sodium cholate solubilization and chromatography on DEAE-Sepharose and 2'5'-ADP-Sepharose columns. Its physicochemical properties were similar to those of the loosely bound form, except for its carbohydrate composition.