| Autor: |
Libby RD; Department of Chemistry, Colby College, Waterville, Maine 04901., Rotberg NS |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of biological chemistry [J Biol Chem] 1990 Sep 05; Vol. 265 (25), pp. 14808-11. |
| Abstrakt: |
The kinetics of chloroperoxidase-catalyzed bromination and chlorination reactions were studied at various halide and hydrogen peroxide concentrations. At very high concentrations, both chloride (KI = 370 mM) and bromide (KI = 150 mM) are competitive substrate inhibitors versus hydrogen peroxide. Results at subinhibitory halide concentrations for bromination reactions (kcat = 4 ms-1, kcat/KPeroxide = 1.6 microM-1 x s-1 and kcat/KBr = 4.0 microM-1 x s-1) and chlorination reactions (kcat = 1.5 ms-1, kcat/Kperoxide = 2.3 microM-1 x s-1, and kcat/KBr = 0.32 microM-1 x s-1) indicate that halide oxidation is rate-limiting in chlorination reactions. However, in bromination reactions, both compound I formation and bromide oxidation are partially rate-limiting. This is the first documented case where compound I formation participates in determining the overall rate of a peroxidase reaction. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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