Glutathione S-transferases YcYfetus and YcYc--kinetic and inhibitor studies relating to their glutathione peroxidase activities.
The kinetic properties of the glutathione (GSH) peroxidase activities of GSH S-transferases YcYfetus and YcYc were compared. The catalytic efficiency of the fetal iso-enzyme with cumene hydroperoxide as substrate was approximately four times higher than the other. The effects of the non-substrate ligand rose-Bengal as well as the substrate ligands sulphobromophthalein and acrolein on the GSH peroxidase activity of these two iso-enzymes were also investigated. Depending on the ligand, the inhibition profiles of these two iso-enzymes when measured with either the peroxidase substrate, cumene hydroperoxide or the standard GSH S-transferase substrate 1-chloro-2,4-dinitrobenzene were found to be either very similar (sulphobromophthalein) or markedly different (rose Bengal and acrolein). Significantly, the GSH peroxidase activity of the fetal iso-enzyme was far less susceptible to inhibition by the teratogen, acrolein, than that of the YcYc isoenzyme. It is therefore attractive to suggest that should a similar situation arise in vivo, this resistance to peroxidase inhibition may play a role in preventing the fetotoxic effects of acrolein.
Scott
T R
TR
Department of Medicine, University of Cape Town.
Kirsch
R E
RE
D000171:Acrolein / Q000378:metabolism; D000818:Animals; D005979:Glutathione Peroxidase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D051381:Rats; D012395:Rose Bengal / Q000378:metabolism; D013448:Sulfobromophthalein / Q000378:metabolism
D007527:Isoenzymes; D013448:Sulfobromophthalein; D012395:Rose Bengal; D000171:Acrolein; D005979:Glutathione Peroxidase; D005982:Glutathione Transferase