[Mechanism of detergent interaction with hemoproteins in aqueous media].

The interactions of myoglobin, cytochrome c, and cytochrome P-450 LM-2 isolated from rabbit liver microsomes with detergents of type A (TM 3-12, Tween 20, Triton N-101) and detergent of B type (sodium cholate) in aqueous media were studied. These interactions are accompanied by a decrease in the Soret band intensity for all three hemoproteins. The rate of this process depends on the nature and concentration of the detergent as well as on temperature. The rate of the Soret band decrease is maximal for the zwitter-ionic surfactant TM 3-12. The rate constants of hemoprotein transformation depend on the detergent concentration. The detergent effects on the conformation and structure of the protein were demonstrated, using CD spectra and second derivatives of the absorption spectra of the hemoproteins in the presence of the detergents. The activation energies for myoglobin transformation in the presence of various detergents are equal to 17-23 kcal/mol and possibly reflect the cleavage of the coordinative heme-apoprotein bonds. A model of detergent interaction with hemoproteins is discussed. According to this model, the bimolecular interaction of the proteins with surfactants is observed at the detergent concentrations that are much lower than those for critical micelle formation values.