Cytochrome P-450 from bovine adrenocortical mitochondria. Immunochemical properties and purity.

This is the authors' abstract. We don't add key points for this paper.

Antibodies were induced against side cleavage P-450 from bovine adrenocortical mitochondria by injecting the enzyme into rabbits. Double diffusion in agarose gels revealed single bands between rabbit anti-P-450 antiserum and adrenal cytochrome P-450 side chain cleavage prepared by two different methods and also with P-450 of different molecular weights called protein 4, protein 8, and large P-450. In addition, the same anti-serum showed a line of identity with an ammonium sulfate fraction which is an impure precursor of pure cytochrome P-450 side chain cleavage in two methods used for its preparation. The IgG fraction from antiserum to P-450 gives a single band with bovine adrenal P-450 side chain cleavage in immunoelectrophoresis. Antiserum to P-450 side chain cleavage inhibits side chain cleavage enzyme activity but not 11β- or 18-hydroxylation and native P-450 competes with 125I-labeled P-450 (side chain cleavage) in combining with anti-P-450 antibodies so that a radioimmunoassay for side chain cleavage P-450 has been developed. Extremely small and possibly nonspecific competition for the anti-P-450 is seen between 125I-labeled P-450 side chain cleavage and 11β-hydroxylase P-450 prepared from the same source. This demonstration of the immunochemical homogeneity of these preparations of P-450 side chain cleavage eliminates one proposed cause for disparity between heme content of the enzyme measured by two different methods; this difference cannot now be attributed to the presence of contaminants.