Cytochrome P450 Monooxygenasesubiquitous in nature:> 40 in humans> 250 in plants>400 in rice

signature motif:F—G-R-C-G

requires redox partner

scission of O2

cytochrome P450 monooxygenase 2C5:

Though low sequence identity among cytochromes P450, overall topology is conserved.

Williams et al., Journal of Inorganic Biochemistry 81 (2002)

-red regions indicate predicted sites of membrane interaction as predicted by antipeptide antibody binding data

-insertion area for CYP2B4:680 ± 95 Å2

interaction with membrane:

Heme binding domain:

heme-thiolate serves asthe 5th ligand to the iron

Arg430, Trp120, and Arg124 forms H-bonds to the proprionate side chains

Thr298 involved in proton relay system

Williams et al., Journal of Inorganic Biochemistry 81 (2002)

Substrate binding pocket:

360Å3 volume

Cyrstal structure confirms mutagenesis studies

Heme iron is 4.8Åfrom site of hydroxylation

Interactions of cytochromes P450 with CPR:

Method:-look for residues that are conserved among P450s-map these residues onto CYP2C5

The proximal face of enzyme contains majority of the conserved residues,most of which are basic residues

distal face

proximal face