| 3426575 |
Hales DB, Ho B, Thompson JA: Inter- and intramolecular deuterium isotope effects on the cytochrome P-450-catalyzed oxidative dehalogenation of 1,1,2,2-tetrachloroethane. Biochem Biophys Res Commun. 1987 Dec 16;149(2):319-25.
The oxidation of 1,1,2,2-tetrachloroethane to dichloroacetic acid was investigated with rat liver microsomes and purified cytochrome P-450. Deuterium substitution had no effect on Km values, but both the inter- and intramolecular isotope effects (kH/kD) on Vmax were in the range 5.7-6.1. The equivalence of the inter- and intramolecular values indicates that 6.0 may be a good estimate of the intrinsic isotope effect. The intermolecular kH/kD value for the conversion of 1,1,2,2-trichloroethane and its 1-2H analog to chloroacetic acid was 5.5. These data, and the finding that 1 atom of 18O was incorporated into the product when TCEA was oxidized in an 18O2 atmosphere, support an oxidative dechlorination mechanism that involves hydrogen atom abstraction by the P-450 intermediate oxo complex. |
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