Interaction of 1,4-benzoquinone and 2,4-dichlorophenoxyacetic acid with microsomal glutathione transferase from rat liver.
Glutathione transferase (GST) was purified from the microsomes of rat liver by glutathione affinity chromatography. The interaction of 2,4-dichlorophenoxyacetic acid (2,4-D) and 1,4-benzoquinone with microsomal GST was investigated and compared with cytosolic GST. The kinetic inhibition pattern of 1,4-benzoquinone towards microsomal GST was found to be different from that towards cytosolic GST. Microsomal GST purified by affinity chromatography was inhibited by 2,4-D in a non dose-dependent manner, while the crude microsomal GST was inhibited in a dose-dependent manner. This difference was shown to be induced by a reaction on the affinity column, and not by Triton X-100 (also shown to be a GST inhibitor), glutathione, or the elution buffer 0.2% Triton X-100 and 5 mM glutathione in 50 mM Tris-HCl, pH 9.6. The binding of microsomal GST to the affinity matrix caused a partial inactivation of the active site for 2,4-D interaction. The results show that the properties of soluble GST enzymes may not be extrapolated to the microsomal ones.
Dierickx
P J
PJ
Instituut voor Hygiëne en Epidemiologie, Brussel.
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology*; D000818:Animals; D016227:Benzoquinones; D002846:Chromatography, Affinity; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D011809:Quinones / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012995:Solubility
D016227:Benzoquinones; D011809:Quinones; D015084:2,4-Dichlorophenoxyacetic Acid; C004532:quinone; D005982:Glutathione Transferase