Cytochrome P450 CYP

Cytochrome P450 (CYP) Cytochrome P450 isozymes Cytochrome P450 mono-oxygenases Mixed function oxidases... 

Cytochrome P450 (CYP) mono-oxygenases, also called mixed function oxidases, are versatile hemoprotein enzymes that catalyze the cleavage of molecular oxygen to incoiporate one oxygen atom into a substrate molecule and one atom into water [1]. The general stoichiometry of the reaction is as follows (S-H, substrate) ... 

Carotenoid oxidation products are also supposed to have detrimental effects in vivo. As mentioned earlier, they are suspected to be involved in the adverse effects of high doses of 3-carotene supplementation in smokers and asbestos workers (CARET and ATBC studies) and in smoke-exposed ferrets. The mechanisms potentially involved have been investigated in vitro. P-Apo-8 -carotenal, an eccennic cleavage oxidation product of P-carotene, was shown to be a strong inducer of CYPlAl in rats, whereas P-carotene was not active. Cytochrome P450 (CYP 450) enzymes thus induced could enhance the activation of carcinogens and the destruction of retinoic acid. ... 

Carrillo, J. A. et al. (2003). Role of the smoking-induced cytochrome P450 (CYP) 1A2 and polymorphic CYP2D6 in steady-state concentration of olanzapine. /. Clin. Psychopharmacol., 23, 119-27. 

Bertilsson, L. (1995). Geographical/interracial differences inpolymorphic drug oxidation current state of knowledge of cytochrome P450 (CYP) 2D6 and 209. Clin. Pharmacokinet., 29, 192— 209. 

Crespi, C. L., Greenblatt, D. J., Comparison between cytochrome P450 (CYP) content and relative activity approaches to scaling from cDNA-expressed CYPs to human liver microsomes ratios of accessory proteins as sources of discrepancies between the approaches, Drug Metab. Dispos. 2000, 28, 1493-1504. 

It has now been established that genetic polymorphisms in drug metabolizing enzymes such as the cytochrome P450s (CYP) and the phase II enzyme, thiopu-rine methyltransferase, are responsible for inter-individual variability in response and adverse reactions [12, 13]. However, at the present time, the impact of poly-... 

The CNS contains much smaller amounts of drug-metabolizing enzymes than does the liver. The concentrations of the main enzymes in the brain, members of the cytochrome P450 (CYP) superfamily, are only 0.25% of concentration in the liver. But the brain enzymes are not uniformly distributed, as they are in the liver they are concentrated in specific brain areas. Theoretical models have explained that drug metabolism in the CNS cannot influence drug distribution in the blood, but there are marked differences in brain tissue levels depending on the presence... 

Moody, G.C. et al. 1999. Fully automated analysis of activities catalysed by the major human liver cytochrome P450 (CYP) enzymes. Xenobiotica. 29 53. 

Pyrethroids Cytochrome P450s (CYP) Carboxylesterases (CES) Others References... 

Moody, G.C., Griffin, S.J., Mather, A.N., McGinnity, D.F. and Riley, R.J. (1999) Fully automated analysis of activities catalysed by the major human liver cytochrome P450 (CYP) enzymes assessment of human CYP inhibition potential. Xenobiotica, 29 (1), 53-75. 

H. and Pelkonen, O. (2006) Cytochrome P450 (CYP) inhibition screening comparison of three tests. European... 

The membrane-attached cytochrome P450 enzymes are involved in a significant fraction of events associated with drug metabolism. Most of the cytochrome P450 (CYP) catalyzed reactions lead to the detoxification of xenobiotics, by forming hydrophilic metabolites that can be readily excreted from the body. 

All tissues except mature red blood cells are able to manufacture haem for use in the respiratory cytochrome proteins of the electron transport chain. However, the liver is an especially important site of haem synthesis because it (a) is a major organ of erythropoiesis in utero and (b) haem-containing cytochrome-P450 (CYP-450) enzymes play significant roles in hepatic detoxification of drugs, toxins and endogenous waste products (Section 6.4). 

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