Equilibrium unfolding of Bombyx mori glycyl-tRNA synthetase.
J Biol Chem
; 276(6): 4028-37, 2001 Feb 09.
Article
en En
| MEDLINE
| ID: mdl-11056158
Unfolding of Bombyx mori glycyl-tRNA synthetase was examined by multiple spectroscopic techniques. Tryptophan fluorescence of wild type enzyme and an N-terminally truncated form (N55) increased at low concentrations of urea or guanidine-HCl followed by a reduction in intensity at intermediate denaturant concentrations; a transition at higher denaturant was detected as decreased fluorescence intensity and a red-shifted emission. Solute quenching of fluorescence indicated that tryptophans become progressively solvent-exposed during unfolding. Wild type enzyme had stronger negative CD bands between 220 and 230 nm than the mutant, indicative of greater alpha-helical content. Urea or guanidine-HCl caused a reduction in ellipticity at 222 nm at low denaturant concentration with the wild type enzyme, a transition that is absent in the mutant; both enzymes exhibited a cooperative transition at higher denaturant concentrations. Both enzymes dissociate to monomers in 1.5 m urea. Unfolding of wild type enzyme is described by a multistate unfolding and a parallel two state unfolding; the two-state component is absent in the mutant. Changes in spectral properties associated with unfolding were largely reversible after dilution to low denaturant. Unfolding of glycyl-tRNA synthetase is complex with a native state, a native-like monomer, partially unfolded states, and the unfolded state.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Bombyx
/
Glicina-ARNt Ligasa
Límite:
Animals
Idioma:
En
Revista:
J Biol Chem
Año:
2001
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos