SHORT COMMUNICATION: Glutathione S-transferase of goat lens: evidence for expression of only class mu isoenzymes

Abstract

PURPOSE. It has been suggested that glutathione S-transferases (GSTs) of the mammalian ocular lens detoxify various toxi-cants and cataractogens; therefore, it provides protection against cataractogenesis. In this study the GST isoenzymes of goat lens have been purified and characterized. METHODS. The goat lens homogenate was subjected to affinity chromatography over GSH-linked epoxy activated Sepharose 6B. The isoenzymes of the GST were separated by chromato-focusing on a Mono-P column using FPLC ®. RESULTS. Two GST isoenzymes, GST 7.2 and GST 6.6, were purified to apparent homogeneity from goat lens. GST 7.2 appeared to be a heterodimer of Mr. 26,500 and Mr. 25,000 subunits, the GST 6.6 showed a homodimeric subunit structure of Mr. 25,000. Western blotting and the N-terminal region amino acid sequence analysis indicated that both isoenzymes of goat lens belong to the µ-class GST. CONCLUSIONS. Although they share varying degrees of structural correlation, the two isoenzymes of goat lens seem to be the products of two distinct genes. The isoenzyme expression pat-tern of GST in goat lens is similar to bovine lens, which also contains two isoenzymes belonging only to GST µ.