title: Infrared spectral studies of carbon monoxide complexes of microsomal cytochromes P-450 and P-448.
abstract: The characteristic infrared spectral parameters of the carbonyl stretching vibration (the maximum position nu CO, the band width at half height delta nu 1/2 and the apparent molar extinction coefficient epsilon M) have been determined for the CO complexes of microsomal cytochromes P-450 (PB-induced) and P-448 (3-MC-induced) from rabbits and rats. The cytochromes P-450 and P-448 from the same species as well as the cytochromes prepared by the same inducer but from the two different species yielded nu CO band parameters different from each other and from the bacterial cytochrome P-450cam [1]. These differences are discussed in connection with (1) the presence of different protein moities (multiple forms) of cytochromes, (2) changes in the order of the nearest neighbour environment (accessibility) of the CO binding site and (3) the presence of (endogenous bound substrate. The heme-carbonyl of the microsomal cytochromes senses subtle changes in the nearest heme environment by changing the solvent from H2O to D2O.
mesh_terms: D000818:Animals; D002164:Camphor; D002248:Carbon Monoxide; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D003580:Cytochromes / Q000378:metabolism; D008748:Methylcholanthrene / Q000494:pharmacology; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology; D011485:Protein Binding; D011817:Rabbits; D051381:Rats; D013055:Spectrophotometry, Infrared
chemical_list: D003580:Cytochromes; D008748:Methylcholanthrene; D002164:Camphor; D002248:Carbon Monoxide; D003577:Cytochrome P-450 Enzyme System; D010634:Phenobarbital