Cytochromes P450 origins

Mancy, A., Dijols, S., Poli, S., Guengerich, P., and Mansuy, D. (1996) Interaction of sulfaphenazole derivatives with human liver cytochromes P450 2C molecular origin of the specific inhibitory effects of sulfaphenazole on CYP 2C9 and consequences for the substrate binding site topology of CYP 2C9. Biochemistry 35, 16,205-16,212. 

Table 5 Inhibition of Human Cytochrome P450-Mediated Metabolism by Aliquots of Aqueous Extracts of Herbal Tea and Bulk Spice (Country of Origin) (25mg/mL Stock Solutions)...

The origin of ricinoleic acid, an abundant constitu-tuent of castor beans, is also shown in Fig. 21-2. It is formed by an oleate hydroxylase that has an amino acid sequence similar to those of oleate desaturases.113 Both hydroxylation and desaturation are reactions catalyzed by diiron centers.114 Other fatty acid hydroxylases act on the alpha115 and the omega positions. The latter are members of the cytochrome P450 family.116 117... 

In the catalytic cycle of CYP, reducing equivalents are transferred from NADPH to CYP by a flavoprotein enzyme known as NADPH-cytochrome P450 reductase. The evidence that this enzyme is involved in CYP monooxygenations was originally derived from the observation that cytochrome c, which can function as an artificial electron acceptor for the enzyme, is an inhibitor of such oxidations. This reductase is an essential component in CYP-catalyzed enzyme systems reconstituted from purified components. Moreover antibodies prepared from purified reductase are inhibitors of microsomal... 

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