MICROSOMAL GLUTATHIONE S-TRANSFERASE - PURIFICATION, INITIAL CHARACTERIZATION AND DEMONSTRATION THAT IT IS NOT IDENTICAL TO THE CYTOSOLIC GLUTATHIONE S-TRANSFERASE-A, S-TRANSFERASE-B AND S-TRANSFERASE-C

  • 1 January 1982
    • journal article
    • research article
    • Vol. 128  (1) , 243-248
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 MW of 14,000 on sodium dodecyl sulfate 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 MW of 127,000 and contains 3 or 4 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 MW and substrate specificity, demonstrate that the microsomal glutathione S-transferase is an enzyme distinct from the cytosolic glutathione S-transferases.