[The role of the hydrophobic fragment of cytochrome b5 in the interaction with cytochrome P-450].
The interaction of highly purified liver microsomal cytochrome P-450 from phenobarbital-induced rabbits and cytochrome b5 has been investigated by the difference and second derivative difference spectroscopy. The addition of cytochrome b5 to cytochrome P-450 results in transition of cytochrome P-450 heme iron from low to high spin state. The interaction is accompanied by the changes in the second derivative spectrum of cytochrome P-450, which point to the participation of tryptophanyl residues in this process. The hydrophilic fragment of cytochrome b5 is unable to form a complex with cytochrome P-450 as judged by the absence of the difference spectrum and any changes in the second derivative UV-spectrum of cytochrome P-450. The evidence obtained indicates that the hydrophobic tail of the cytochrome b5 molecule responsible for its binding to membrane is also indispensable for forming a functional cytochrome P-450-cytochrome b5 complex.
D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002942:Circular Dichroism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003573:Cytochrome b Group / Q000378:metabolism*; D015786:Cytochromes b5; D008563:Membrane Lipids / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology*; D010743:Phospholipids / Q000378:metabolism; D011817:Rabbits; D013056:Spectrophotometry, Ultraviolet
D003573:Cytochrome b Group; D008563:Membrane Lipids; D010743:Phospholipids; D015786:Cytochromes b5; D003577:Cytochrome P-450 Enzyme System
Rol' gidrofobnogo fragmenta tsitokhroma b5 pri vzaimodeĭstvii s tsitokhromom P-450.