Crystallographic observation of a covalent catalytic intermediate in a beta-glycosidase.
Nat Struct Biol
; 3(2): 149-54, 1996 Feb.
Article
em En
| MEDLINE
| ID: mdl-8564541
ABSTRACT
The three-dimensional structure of a catalytically competent glycosyl-enzyme intermediate of a retaining beta-1,4-glycanase has been determined at a resolution of 1.8 A by X-ray diffraction. A fluorinated slow substrate forms an alpha-D-glycopyranosyl linkage to one of the two invariant carboxylates, Glu 233, as supported in solution by 19F-NMR studies. The resulting ester linkage is coplanar with the cyclic oxygen of the proximal saccharide and is inferred to form a strong hydrogen bond with the 2-hydroxyl of that saccharide unit in natural substrates. The active-site architecture of this covalent intermediate gives insights into both the classical double-displacement catalytic mechanism and the basis for the enzyme's specificity.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Xilosidases
/
Beta-Glucosidase
/
Endo-1,4-beta-Xilanases
Idioma:
En
Revista:
Nat Struct Biol
Assunto da revista:
BIOLOGIA MOLECULAR
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Canadá