title: Microsomal glutathione S-transferase. Purification, initial characterization and demonstration that it is not identical to the cytosolic glutathione S-transferases A, B and C.
abstract: Rat liver microsomal glutathione S-transferase was activated with N-ethylmaleimide, solubilized with Triton X-100, and purified by chromatography on hydroxyapatite and CM-Sepharose. A 36-fold purification resulted in a 36% yield, indicating that the glutathione S-transferase accounts for 2.5-3% of the original microsomal protein. The purified protein moved as a band with an apparent molecular weight of 14 000 on sodium dodecyl sulphate gel electrophoresis and appeared to be nearly homogeneous. The complex formed between the purified microsomal glutathione S-transferase and Triton X-100 has a sedimentation coefficient of 3.2 S, a partial specific volume of 0.844 cm3/g, and a Stokes radius of 5.5 nm. The complex has a molecular weight of 127 000 and contains three or four polypeptide chains and 112-134 detergent molecules. Antibodies directed against soluble glutathione S-transferases A, B and C do not react with the purified microsomal enzyme. This finding, together with differences in molecular weight and substrate specificity, demonstrate that the microsomal glutathione S-transferase is an enzyme distinct from the cytosolic glutathione S-transferases.
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D003600:Cytosol / Q000201:enzymology*; D004792:Enzyme Precursors / Q000145:classification; D005982:Glutathione Transferase / Q000145:classification / Q000302:isolation & purification*; D007120:Immunochemistry; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity
chemical_list: D004792:Enzyme Precursors; D005982:Glutathione Transferase