A calorimetric study of the binding of S-alkylglutathiones to glutathione S-transferase
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Ortiz Salmerón, Emilia; Clemente Jiménez, Josefa María; Las Heras Vázquez, Francisco Javier; Rodríguez Vico, Felipe; Barón Bravo, Carmen Francisca; [et al.]Fecha
2001Resumen
The binding of three competitive glutathione analogue inhibitors (S-alkylglutathione derivatives) to glutathione
S-transferase from Schistosoma japonicum, SjGST, has been investigated by isothermal titration microcalorimetry at pH
6.5 over a temperature range of 15^30³C. Calorimetric measurements in various buffer systems with different ionization heats
suggest that no protons are exchanged during the binding of S-alkylglutathione derivatives. Thus, at pH 6.5, the protons
released during the binding of substrate may be from its thiol group. Calorimetric analyses show that S-methyl-, S-butyl-,
and S-octylglutathione bind to two equal and independent sites in the dimer of SjGST. The affinity of these inhibitors to
SjGST is greater as the number of methylene groups in the hydrocarbon side chain increases. In all cases studied, vG0
remains invariant as a function of temperature, while vHb and vS0 both decrease as the temperature increases. The binding
of three S-alkylglutathione de...
Palabra/s clave
Glutathione S-transferase
S-Methylglutathione
S-Butylglutathione
S-Octylglutathione
Binding
Microcalorimetry
Schistosoma japonicum