title: Reversible transfer of heme between different molecular species of microsome-bound cytochrome P-450 in rat liver.
abstract: Incorporation of newly synthesized heme into microsome-bound cytochrome P-450 in rat liver was not affected by cycloheximide administration to the animals, indicating that the heme incorporation into cytochrome P-450 is not tightly coupled with the synthesis of the apo-cytochrome. When the heme of microsomal cytochrome P-450 had been labeled in vivo with delta-[14C]aminolevulinic acid, and then the animals were treated with phenobarbital (PB) or 3-methylcholanthrene (MC), PB-induced or MC-induced form of cytochrome P-450 was found to contain labeled heme derived from preexistent cytochrome P-450. These observations indicated that the heme of microsome-bound cytochrome P-450 is not tightly associated with the protein portion, and exchanges reversibly between different molecular species of cytochrome P-450 in vivo.
mesh_terms: D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D006418:Heme / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D008748:Methylcholanthrene / Q000494:pharmacology; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology; D051381:Rats
chemical_list: D007527:Isoenzymes; D006418:Heme; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D003513:Cycloheximide; D010634:Phenobarbital