Hydrodynamic properties of monomeric cytochromes P-450LM2 and P-450LM4 in n-octylglucoside solution

Sedimentation equilibrium and sedimentation velocity measurements were carried out on cytochrome P-450_LM2 from phenobarbital-treated rabbit liver and on cytochrome P-450_LM4 from 5,6-benzoflavone-treated rabbit liver in the presence of the nonionic detergent $\text{1-O-}\text{n}\text{-}\text{octyl}\text{-β-}\text{D}\text{-}\text{glucopyranoside}$. P-450_LM2 was monomeric with a molecular weight of 48,800 and a Stokes radius of 3.1 nm in 7 g/l detergent and P-450_LM4 was monomeric with a molecular weight of 49,800 and a Stokes radius of 2.6 nm at 5 g/l detergent. Both particles were spherical in shape under these conditions. Neither cytochrome was irreversibly denatured at these detergent concentrations as indicated by the ability to form substantial amounts (>60%) of the CO adduct with an absorption maximum at 451 nm (P-450_LM2) or 448 nm (P-450_LM4) when diluted into detergent-free buffer containing CO and sodium dithionite.