Role of the hydrophobic tail of cytochrome b5 in the interaction with cytochrome P-450 LM2.

The interaction of cytochrome P-450 LM2 with cytochrome b5 is accompanied by a high spin shift in P-450 LM2 and the improvement of a second derivative spectra in the near ultraviolet region. After incorporation into phospholipid vesicles the interaction between P-450 LM2 and b5 is increased according to a decrease of the apparent binding constant. The involvement of a tryptophanyl residue in the interaction will be discussed. Contrary the tryptic fragment of cytochrome b5 which lacks the membrane binding tail does not show an interaction with P-450 LM2 either in the absence or presence of phospholipids.