[Interaction of the components of the cytochrome P-450 monooxygenase system from liver microsomes. I. Immobilization of the solubilized and partially purified protein components].

The method of matrix fixation has been used to study the interaction between the components of the cytochrome P-450 monooxygenases from rat liver microsomes. The solubilized, isolated protein components were covalently bound to BrCN-activated. Sepharose in different ways and subsequently the N-demethylase activity was determined. It has been proved that in each case of fixation a certain amount of activity could be determined. However the degree of activity varied in dependence on the sequence and number of bound components. The activity compared with the reconstituted soluble system decreased in the following sequence: single fixation of NADPH-cytochrome P-450 reductase (40%), of cytochrome P-450 (23%); sequential fixation: first component cytochrome P-450 (33%), first component NADPH-cytochrome P-450 reductase (8%). Simultaneous fixation of both components yielded a lower activity. From the results it was concluded that the activity is influenced by some kind of self-assembly.