Hydrodynamic studies on interactions between the components of the liver microsomal cytochrome P-450 system.
To understand the different behaviour of cytochrome P-450 systems in kinetics as well as in the demethylase activity, sedimentation and molecular weight experiments have been carried out with the following results: 1) Sedimentation coefficients of solubilized P-450 and P-450 LM2 fractions amount to 24 +/- 4 [S] and 12.8 +/- 1.2 [S], respectively. Molecular weights were determined to be 1.0 +/- 0.2 . 10(6) and 3.0 +/- 0.5 . 10(5) Dalton. 2) Triton N-101 provokes splitting of the associated structure both of solubilized P-450 and P-450 LM2; this effect is reversible. 3) The dissociation depends not only on the absolute concentration of Triton but rather on the Triton P-450 ratio. The dissociation curves of solubilized P-450 and P-450 LM2 are similar in shape and in the Triton/P-450 ratio dependence. 4) In the presence of small concentrations of Triton a more complicated dissociation behaviour was observed with broad integral distribution of the sedimentation coefficients. 5) The ionic detergent cholate splits the associated structure of P-450 LM2 at considerably higher concentrations in comparison with Triton-N 101. 6) Addition of reductase causes a decrease of sedimentation coefficients and molecular weights of solubilized P-450. The same effect in P-450 LM2 could be observed only in the presence of phospholipids.
D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D008970:Molecular Weight; D010634:Phenobarbital / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000494:pharmacology; D011817:Rabbits; D012995:Solubility
D046911:Macromolecular Substances; D011092:Polyethylene Glycols; D003577:Cytochrome P-450 Enzyme System; D010634:Phenobarbital