Photooxidation of cytochrome P450-BM3.
Proc Natl Acad Sci U S A
; 107(44): 18783-6, 2010 Nov 02.
Article
en En
| MEDLINE
| ID: mdl-20947800
ABSTRACT
High-valent iron-oxo species are thought to be intermediates in the catalytic cycles of oxygenases and peroxidases. An attractive route to these iron-oxo intermediates involves laser flash-quench oxidation of ferric hemes, as demonstrated by our work on the ferryl (compound II) and ferryl porphyrin radical cation (compound I) intermediates of horseradish peroxidase. Extension of this work to include cytochrome P450-BM3 (CYP102A1) has required covalent attachment of a Ru(II) photosensitizer to a nonnative cysteine near the heme (RuIIK97C-FeIIIP450), in order to promote electron transfer from the Fe(III) porphyrin to photogenerated Ru(III). The conjugate was structurally characterized by X-ray crystallography (2.4 Å resolution; Ru-Fe distance, 24 Å). Flash-quench oxidation of the ferric-aquo heme produces an Fe(IV)-hydroxide species (compound II) within 2 ms. Difference spectra for three singly oxidized P450-BM3 intermediates were obtained from kinetics modeling of the transient absorption data in combination with generalized singular value decomposition analysis and multiexponential fitting.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Bacterianas
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NADPH-Ferrihemoproteína Reductasa
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Sistema Enzimático del Citocromo P-450
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Procesos Fotoquímicos
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Hemo
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Modelos Químicos
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Año:
2010
Tipo del documento:
Article
País de afiliación:
Estados Unidos