An optical biosensor study of the interaction parameters and role of hydrophobic tails of cytochrome P450 2B4, b5 and NADPH-flavoprotein in complex formation.

The real-time interactions of membrane proteins - cytochrome P450 2B4, NADPH cytochrome P450 reductase and cytochrome b5 - were studied by use of an optical biosensor system. The association and dissociation rate constants for the individual complexes were measured and the affinities of the redox partners for each other were estimated. The association rate constants of these complexes were found to be close to the diffusion limit and their dissociation rate constants were in the order of 1s-1. A dominant role of the interaction of the membraneous hydrophobic fragments in the formation of productive electron transferring complexes between the proteins was demonstrated.