Orientation, accessibility, and mobility of equilenin bound to the active site of steroid isomerase.
Biochemistry
; 28(15): 6269-75, 1989 Jul 25.
Article
en En
| MEDLINE
| ID: mdl-2675967
The fluorescent aromatic steroid equilenin, which contains a beta-naphthol moiety, is bound by 3-oxo-delta 5-steroid isomerase. The excitation and emission fluorescence spectra of equilenin when bound to the enzyme, as well as the fluorescence decay time, are indicative of ground-state ionization. In view of the high efficiency of tyrosine quenching, which approaches 100%, the beta-naphthol moiety of equilenin must be in proximity to all three tyrosines of steroid isomerase to account for the observed efficiency of radiationless energy transfer. From the observed response to an external quencher, it appears that enzyme-bound equilenin is largely shielded from solvent. Fluorescence anisotropy measurements indicate a high degree of immobilization of the bound ligand. These models are consistent with proposed models of the enzyme-substrate complex.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Esteroide Isomerasas
/
Equilenina
/
Isomerasas
/
17-Cetosteroides
Idioma:
En
Revista:
Biochemistry
Año:
1989
Tipo del documento:
Article
Pais de publicación:
Estados Unidos