Probing the role of the proximal heme ligand in cytochrome P450cam by recombinant incorporation of selenocysteine.
Proc Natl Acad Sci U S A
; 106(14): 5481-6, 2009 Apr 07.
Article
em En
| MEDLINE
| ID: mdl-19293375
ABSTRACT
The unique monooxygenase activity of cytochrome P450cam has been attributed to coordination of a cysteine thiolate to the heme cofactor. To investigate this interaction, we replaced cysteine with the more electron-donating selenocysteine. Good yields of the selenoenzyme were obtained by bacterial expression of an engineered gene containing the requisite UGA codon for selenocysteine and a simplified yet functional selenocysteine insertion sequence (SECIS). The sulfur-to-selenium substitution subtly modulates the structural, electronic, and catalytic properties of the enzyme. Catalytic activity decreases only 2-fold, whereas substrate oxidation becomes partially uncoupled from electron transfer, implying a more complex role for the axial ligand than generally assumed.
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Base de dados:
MEDLINE
Assunto principal:
Engenharia de Proteínas
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Técnicas de Sonda Molecular
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Selenocisteína
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Cânfora 5-Mono-Oxigenase
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
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