Mechanism and stoichiometry of 2,2-diphenyl-1-picrylhydrazyl radical scavenging by glutathione and its novel alpha-glutamyl derivative.
Bioorg Chem
; 37(4): 126-32, 2009 Aug.
Article
en En
| MEDLINE
| ID: mdl-19487009
Kinetic mechanism and stoichiometry of scavenging the 2,2-diphenyl-1-picrylhydrazyl radical by glutathione and its novel analog, containing alpha-glutamyl residue in place of the gamma-glutamyl moiety, were studied using different ratios of reagents. At low concentrations of the peptides, the process was described as a bimolecular reaction obeying the stoichiometric ratio 1:1. However, at excess of peptides the formation of a non-covalent complex between the reagents was discovered and characterized by dissociation constants K = 0.61 mM for glutathione and K = 0.27 mM for the glutathione alpha-glutamyl analog, respectively. The complex formation was followed by a reaction step that was characterized by the similar rate constant k = 0.02 s(-1) for both peptides. Thus, the apparently different antioxidant activity of these two peptides, observed under common assay conditions, was determined by differences in the formation of this non-covalent complex.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Picratos
/
Compuestos de Bifenilo
/
Depuradores de Radicales Libres
/
Glutatión
Idioma:
En
Revista:
Bioorg Chem
Año:
2009
Tipo del documento:
Article
País de afiliación:
Estonia
Pais de publicación:
Estados Unidos