Thermodynamics of glutathione binding to the tyrosine 7 to phenylalanine mutant of glutathione S-transferase from Schistosoma japonicum.
The binding of glutathione (GSH) to the tyrosine 7 to phenylalanine mutant of Schistosoma japonicum glutathione S-transferase (SjGST-Y7F) has been studied by isothermal titration calorimetry (ITC). At pH 6.5 and 25 degrees C this mutant shows a higher affinity for glutathione than wild type enzyme despite an almost complete loss of activity in the presence of 1-chloro-2,4-dinitrobenzene (CDNB) as second substrate. The enthalpy change upon binding of GSH is more negative for the mutant than for the wild type GST (SjGST). Changes in accessible solvent areas (ASA) have been calculated based on enthalpy and heat capacity changes. ASA values indicated the burial of apolar surfaces of protein and ligand upon binding. A more negative DeltaC(p) value has been obtained for the mutant enzyme, suggesting a more hydrophobic interaction, as may be expected from the change of a tyrosine residue to phenylalanine.
Andújar-Sánchez
Montserrat
M
Dpto. Química Física, Bioquímica y Química Inorgánica, Universidad de Almeri;a, Carretera Sacramento s/n, Almería, Spain.
Clemente-Jiménez
Josefa María
JM
Las Heras-Vázquez
Francisco Javier
FJ
Rodríguez-Vico
Felipe
F
Cámara-Artigas
Ana
A
Jara-Pérez
Vicente
V
D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D001665:Binding Sites; D002151:Calorimetry; D005978:Glutathione / Q000378:metabolism*; D005982:Glutathione Transferase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010649:Phenylalanine / Q000235:genetics*; D011485:Protein Binding; D011487:Protein Conformation; D012549:Schistosoma japonicum / Q000201:enzymology*; D012997:Solvents / Q000737:chemistry; D055672:Static Electricity; D013696:Temperature; D013816:Thermodynamics; D017186:Titrimetry; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*
D012997:Solvents; D014443:Tyrosine; D010649:Phenylalanine; D005982:Glutathione Transferase; D005978:Glutathione