[Biosynthesis in the rat liver of a common form of monooxygenase induced by xenobiotics of a methylcholanthrene series].

Injection of Wistar rats with five structurally different inducers of methylcholanthrene-type (polycyclic aromatic and heterocyclic hydrocarbons, chloro-derivatives of biphenyl and dibenzo-p-dioxin) results in the de novo synthesis of two P-448 hemoproteins (molecular weight 56 000 and 53 000 Da) differing in their functional and immunochemical properties in liver microsomes. A comparison of catalytic and immunochemical characteristics of five cytochrome P-448 forms (Mr = 56 000 Da) as well as the data from electrophoretic, proteolytic and inhibitory analyses revealed no differences in the preparations used, with the exception of 2,3,7,8-tetrachloro-dibenzo-p-dioxin-induced microsomes characterized by a low level of this cytochrome P-448 form and a higher molecular activity as compared with 3,4-benzpyrene and 7-ethoxyresorufin-induced microsomes. The experimental results do not confirm the hypothesis on the feasibility of induced synthesis of a variety of individual forms of monooxygenase that would correlate with the number of structural variants of inducers.