Compact acid-induced state of Clitoria ternatea agglutinin retains its biological activity.
Biochemistry (Mosc)
; 74(10): 1088-95, 2009 Oct.
Article
en En
| MEDLINE
| ID: mdl-19916921
The effects of pH on Clitoria ternatea agglutinin (CTA) were studied by spectroscopy, size-exclusion chromatography, and by measuring carbohydrate specificity. At pH 2.6, CTA lacks well-defined tertiary structure, as seen by fluorescence and near-UV CD spectra. Far-UV CD spectra show retention of 50% native-like secondary structure. The mean residue ellipticity at 217 nm plotted against pH showed a transition around pH 4.0 with loss of secondary structure leading to the formation of an acid-unfolded state. This state is relatively less denatured than the state induced by 6 M guanidine hydrochloride. With a further decrease in pH, this unfolded state regains ~75% secondary structure at pH 1.2, leading to the formation of the A-state with native-like near-UV CD spectral features. Enhanced 8-anilino-1-naphthalene-sulfonate binding was observed in A-state, indicating a "molten-globule" like conformation with exposed hydrophobic residues. Acrylamide quenching data exhibit reduced accessibility of quencher to tryptophan, suggesting a compact conformation at low pH. Size-exclusion chromatography shows the presence of a compact intermediate with hydrodynamic size corresponding to a monomer. Thermal denaturation of the native state was cooperative single-step transition and of the A-state was non-cooperative two-step transition. A-State regains 72% of the carbohydrate-binding activity.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Ácidos
/
Venenos de Cnidarios
/
Clitoria
/
Aglutininas
Idioma:
En
Revista:
Biochemistry (Mosc)
Año:
2009
Tipo del documento:
Article
País de afiliación:
India
Pais de publicación:
Estados Unidos