Hole Hopping through Tryptophan in Cytochrome P450.
Biochemistry
; 56(28): 3531-3538, 2017 07 18.
Article
en En
| MEDLINE
| ID: mdl-28689401
ABSTRACT
Electron-transfer kinetics have been measured in four conjugates of cytochrome P450 with surface-bound Ru-photosensitizers. The conjugates are constructed with enzymes from Bacillus megaterium (CYP102A1) and Sulfolobus acidocaldarius (CYP119). A W96 residue lies in the path between Ru and the heme in CYP102A1, whereas H76 is present at the analogous location in CYP119. Two additional conjugates have been prepared with (CYP102A1)W96H and (CYP119)H76W mutant enzymes. Heme oxidation by photochemically generated Ru3+ leads to P450 compound II formation when a tryptophan residue is in the path between Ru and the heme; no heme oxidation is observed when histidine occupies this position. The data indicate that heme oxidation proceeds via two-step tunneling through a tryptophan radical intermediate. In contrast, heme reduction by photochemically generated Ru+ proceeds in a single electron tunneling step with closely similar rate constants for all four conjugates.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Rutenio
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Bacillus megaterium
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Triptófano
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Sulfolobus acidocaldarius
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Fármacos Fotosensibilizantes
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Sistema Enzimático del Citocromo P-450
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Hemo
Idioma:
En
Revista:
Biochemistry
Año:
2017
Tipo del documento:
Article
País de afiliación:
Estados Unidos