Novel human ocular glutathione S-transferases with high activity toward 4-hydroxynonenal.

摘要: PURPOSE To study the distribution and expression of glutathione S-transferase isozymes involved in detoxification endogenously generated toxic products lipid peroxidation, namely, 4-hydroxynonenal (4-HNE) human lens, retina, cornea, iris, ciliary body to their kinetic structural properties. METHODS The authors have previously cloned sequenced cDNA mouse mGSTA4-4, which shows high activity towards 4-HNE. They expressed it Escherichia coli raised antibodies against recombinant mGSTA4-4. In present study, these were used Western blot analysis immunoaffinity chromatography purify ortholog(s) mGSTA4-4 from ocular tissues. RESULTS analyses tissues indicated that a S-transferases (GST) isozyme immunologically similar was iris body, but not lens. This designated as hGST 5.8 purified homogeneity by immunoabsorption on immobilized ortholog all pI value 5.8, subunit Mr 25 k blocked N-terminal. Amino acid sequences CNBr fragments showed degree primary structure homologies with corresponding regions There noticeable differences amino suggesting presence several closely related subunits heterogeneity due tissue-specific rather than simple allelic polymorphism. had about sixfold eightfold higher toward 1-chloro-2,4-dinitrobenzene, or CDNB. catalytic efficiency (Kcat/Km) for 4-HNE 100-fold those alpha, mu, pi classes GST. addition, peroxidase phospholipid hydroperoxides GSH-conjugating 9,10-epoxy stearic acid. CONCLUSIONS results indicate isozyme(s) distinct GSTs, are differentially may play an important role protective mechanisms endogenous toxicants during peroxidation.