title: Separation of two constitutive forms of cytochrome P-450 active in aminopyrine N-demethylation from rabbit intestinal mucosa microsomes.
abstract: Two constitutive forms of cytochrome P-450, designated P-450ib and P-450ic, were purified from intestinal mucosa microsomes of untreated rabbits. P-450ib and P-450ic have minimal molecular weights of 56 000 and 49 000, respectively, as determined by calibrated sodium dodecyl sulphate polyacrylamide gel electrophoresis. The CO-reduced difference spectral maximum of cytochrome P-450ib is at 450 nm and P-450ic is at 451 nm. Both the cytochromes preferentially demethylate aminopyrine, benzphetamine and N,N-dimethylaniline in the presence of NADPH-cytochrome P-450 reductase. Cytochrome P-450ib has absorption maxima at 417, 535 and 573 nm in the oxidized form, indicating that this cytochrome is in a low-spin state. Ouchterlony double-diffusion studies show that cytochrome P-450ib does not cross-react with antisera against liver cytochrome P-450LM2 purified from phenobarbital-treated rabbits, but P-450ic cross-reacts with spur formation. Unlike cytochrome P-450ib, P-450ic is very similar, if not identical, to liver cytochrome P-450LM2 on the basis of its molecular weight, spectral properties, catalytic activities and immunochemical properties.
mesh_terms: D000633:Aminopyrine N-Demethylase / Q000378:metabolism*; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism; D005779:Immunodiffusion; D007413:Intestinal Mucosa / Q000648:ultrastructure*; D007527:Isoenzymes / Q000302:isolation & purification*; D008297:Male; D008861:Microsomes / Q000201:enzymology*; D008970:Molecular Weight; D010206:Papain / Q000378:metabolism; D011817:Rabbits; D012697:Serine Endopeptidases
chemical_list: D007527:Isoenzymes; D003577:Cytochrome P-450 Enzyme System; D000633:Aminopyrine N-Demethylase; D010450:Endopeptidases; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D010206:Papain