BIOL 263 |
| Human cytochrome P450s (P450s) 2S1 and 2W1 have received only limited attention with regard to characterization of function. Both P450s have been reported to be overexpressed in human tumors, and P450 2S1 is induced by carcinogenic polycyclic hydrocarbons. We achieved high-level expression of both P450s from Escherichia coli with the goal of establishing function. The levels of expression of human P450 2W1 (codon optimization for E. coli) and 2S1 were 1800 and 600 nmol P450/liter culture. P450 2W1 catalyzed benzphetamine N-demethylation (kcat 3.8 min-1) and also arachidonic acid oxidation, albeit at a very low rate (~ 0.05 min-1). In a umu genotoxicity screen, P450 2W1 catalyzed the activation of several pro-carcinogens, particularly polycyclic hydrocarbon diols, but P450 2S1 did not. The bioactivation of pro-carcinogens by P450 2W1 may be of significance in the context of reports of preferential expression of the enzyme in tumors, in that activation of procarcinogens could lead to accumulation of mutations and enhance the carcinogenic process. (Supported in part by USPHS R01 CA90426 and P30 ES00267) |
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Enzymes
4:30 PM-6:30 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster
Division of Biological Chemistry |