Comparison of the structural stability of two homologous toxins isolated from the Taiwan cobra (Naja naja atra) venom.
Biochemistry
; 39(30): 8705-10, 2000 Aug 01.
Article
en En
| MEDLINE
| ID: mdl-10913281
ABSTRACT
Cardiotoxin analogue III (CTX III) and cobrotoxin (CBTX) isolated from the Taiwan cobra venom (Naja naja atra) are structurally homologous, small molecular weight, all-beta-sheet proteins, cross-linked by four disulfide bonds at identical positions. The conformational stabilities of these toxins are compared based on temperature-dependent chemical shifts and amide proton exchange kinetics using two-dimensional NMR spectroscopy. The structure of CTX III is found to be significantly more stable than that of CBTX. In both the toxins, beta-strand III appears to constitute the stability core. In CTX III, the stability of the triple-stranded beta-sheet domain is observed to be markedly higher than the double-stranded beta-sheet segment. In contrast, in CBTX, both structural domains (double- and triple-stranded beta-sheet domains) appear to contribute equally to the stability of the protein. Estimation of the free energy of exchange (Delta G(ex)) of residues in CBTX and CTX III reveals that the enhanced stability of the structure of CTX III stems from the strong interactions among the beta-strands constituting the triple-stranded beta-sheet domain and also the molecular forces bridging the residues at the N- and C-terminal ends of the molecule.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Proteínas Neurotóxicas de Elápidos
/
Proteínas Cardiotóxicas de Elápidos
Límite:
Animals
Idioma:
En
Revista:
Biochemistry
Año:
2000
Tipo del documento:
Article
País de afiliación:
China