[Hexameric organization of cytochrome P-450LM4 isolated from rabbit hepatocyte endoplasmic reticulum membrane].

In pure protein preparations (monodisperse according to sedimentation analysis data) microsomal cytochrome P-450LM4 (cytochrome P-448) is represented by hexameric associates resembling those of cytochrome P-450LM2 previously characterized in this laboratory. Under conditions preventing nonspecific aggregation of membrane hemoproteins, these two cytochrome isoforms have very close sedimentation coefficients. As the LM4 displays a much higher hydrophobicity in comparison with LM2, which significantly hampers the determination of its hydrodynamic characteristics and the molecular masses of its oligomers by other trivial methods, the LM4 oligomers were characterized by comparing the dissociation patterns of LM2 and LM4 oligomers immobilized on an insoluble carrier. The dissociation regime used in those studies promoted a covalent attachment to the carrier of no more than one promoter in each oligomer.