Stabilization of a metastable state of Torpedo californica acetylcholinesterase by chemical chaperones.
Protein Sci
; 12(10): 2337-47, 2003 Oct.
Article
en En
| MEDLINE
| ID: mdl-14500892
Chemical modification of Torpedo californica acetylcholinesterase by the natural thiosulfinate allicin produces an inactive enzyme through reaction with the buried cysteine Cys 231. Optical spectroscopy shows that the modified enzyme is "native-like," and inactivation can be reversed by exposure to reduced glutathione. The allicin-modified enzyme is, however, metastable, and is converted spontaneously and irreversibly, at room temperature, with t(1/2) approximately 100 min, to a stable, partially unfolded state with the physicochemical characteristics of a molten globule. Osmolytes, including trimethylamine-N-oxide, glycerol, and sucrose, and the divalent cations, Ca(2+), Mg(2+), and Mn(2+) can prevent this transition of the native-like state for >24 h at room temperature. Trimethylamine-N-oxide and Mg(2+) can also stabilize the native enzyme, with only slight inactivation being observed over several hours at 39 degrees C, whereas in their absence it is totally inactivated within 5 min. The stabilizing effects of the osmolytes can be explained by their differential interaction with the native and native-like states, resulting in a shift of equilibrium toward the native state. The stabilizing effects of the divalent cations can be ascribed to direct stabilization of the native state, as supported by differential scanning calorimetry.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Perileno
/
Acetilcolinesterasa
/
Ácidos Sulfínicos
/
Estabilidad de Enzimas
/
Torpedo
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Protein Sci
Asunto de la revista:
BIOQUIMICA
Año:
2003
Tipo del documento:
Article
País de afiliación:
Israel
Pais de publicación:
Estados Unidos