Glutathione S-transferase of goat lens: evidence for expression of only class mu isoenzymes.
OBJECTIVE
It has been suggested that glutathione S-transferases (GSTs) of the mammalian ocular lens detoxify various toxicants 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 chromatofocusing 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 mu-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 pattern of GST in goat lens is similar to bovine lens, which also contains two isoenzymes belonging only to GST mu.
Ahmad
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Department of Chemistry, University of Texas-Pan American, Edinburg 78539, USA. ahmadh@panam.edu
Tobola
A S
AS
Silva
A
A
Castillo
R
R
D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D005982:Glutathione Transferase / Q000302:isolation & purification / Q000378:metabolism*; D006041:Goats; D006801:Humans; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D007908:Lens, Crystalline / Q000201:enzymology*; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011817:Rabbits; D017386:Sequence Homology, Amino Acid
D007527:Isoenzymes; D005982:Glutathione Transferase