The true hydrophobicity of microsomal cytochrome P-450 in the rat. Size dependence of the free energy of binding of a series of hydrocarbon substrates from the aqueous phase to the enzyme and to the membrane as derived from spectral binding data.

Abstract

By extension of these studies, this laboratory has developed a method for the determination of the microsomal partition coefficient from such binding data.However, these equations cannot be used per se to determine the orientation of the type I binding site with respect to the microsomal membrane.Making use of the above concepts, and making allowances for the presence of organic solvents where appropriate, the associations of some hydrophobic substrates with cytochrome P-450 and with the microsomal membrane were studied.A series of aromatic hydrocarbons of increasing molecular size were used as a probe of the type I site of cytochrome P-450.The size