Polyclonal antibody elicited in a rabbit against purified cytochrome P-450cc25, which catalyzes 25-hydroxylation of vitamin D3, inhibited not only 25-hydroxylation of cholecal-ciferol and 1α-hydroxycholecalciferol, but also 16α- and 2α-hydroxylation of testosterone catalyzed by the purified P-450cc25 preparation. Antibody inhibition experiments with microsomes revealed that most 16α- and 2α-hydroxylation of testosterone and most 25-hydroxylation of cholecalciferol by male rat liver microsomes were catalyzed by P-450cc25. In order to examine the identity of cholecalciferol 25-hydroxylase and testosterone 16α-hydroxylase, monoclonal antibodies recognizing three different epitopes of P-450cc25 were prepared from hybridoma clones produced by fusion of mouse myeloma cells (P3X63Ag8U1) with the spleen cells of immunized BALB/c mouse. All of these monoclonal antibodies inhibited both 25-hydroxylation of 1α-hydroxycholecalciferol and 16α-hydroxylation of testosterone by purified P-450cc25. These observations suggested that immunochemically indistinguishable form(s) of cytochrome P-450 catalyzed both reactions.
|Number of pages||5|
|Journal||Journal of biochemistry|
|Publication status||Published - 1988 May|
ASJC Scopus subject areas
- Molecular Biology