Glutathione S-transferase, similar to sigma class, from skin secretions ofXenopus laevis

Using glutathione affinity chromatography followed by isoelectrofocusing, w e purified from the skin secretion of Xenopus laevis an isoenzyme of glutat hione S-transferase with an apparent subunit molecular mass of 22.5 kDa and an isoelectric point at pH 5.1, Its N-terminal amino acid sequence was hig hly similar to that of the sigma class glutathione S-transferase, which pre viously was demonstrated to have a glutathione-dependent prostaglandin D-2 synthase activity: Immunohistochemistry analysis revealed that the isoenzym e was located in the cytoplasm of granular gland cells.