Schistosoma mansoni: single-step purification and characterization of glutathione S-transferase isoenzyme 4.
A soluble glutathione S-transferase isoenzyme, designated SmGST-4 was purified to apparent homogeneity in a single step from the cytosol of adult Schistosoma mansoni by selective elution of the enzyme from a glutathione-agarose affinity column using glutathione disulfide. SmGST-4, which comprised about 5% of the bound glutathione S-transferase activity, could be distinguished from the previously characterized glutathione S-transferase isoenzyme family (SmGST-1/2/3), by its unique chromatographic behavior, lower subunit M(r) (26,000), differences in substrate specificity and inhibitor sensitivity, and a lack of reactivity with antiserum to SmGST-3. The purified isoenzyme catalyzed the conjugation of several model xenobiotics including 1-chloro-2,4-dinitrobenzene, ethacrynic acid, and trans-4-phenyl-3-buten-2-one. Like the SmGST-1/2/3 isoenzyme family, SmGST-4 failed to catalyze the conjugation of a model epoxide substrate, 1,2-epoxy-3-(p-nitrophenoxy)propane. Because glutathione S-transferases from other organisms play a role in protecting cells against the toxic products of lipid peroxidation, SmGST-4 and the members of the SmGST-1/2/3 isoenzyme family were tested for their capacity to reduce cumene hydroperoxide and to catalyze the conjugation of 4-hydroxyalk-2-enals. Although all four isoenzymes catalyzed both reactions, the specific activity of SmGST-1, SmGST-2, and SmGST-3 toward cumene hydroperoxide was at least 10-fold greater than that of SmGST-4. In contrast, the latter more effectively conjugated a homologous series of 4-hydroxyalk-2-enal isomers.(ABSTRACT TRUNCATED AT 250 WORDS)
O'Leary
K A
KA
Department of Comparative Biosciences, University of Wisconsin, Madison 53706-1102.
Hathaway
K M
KM
Tracy
J W
JW
D000818:Animals; D002853:Chromatography, Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D015151:Immunoblotting; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism; D012550:Schistosoma mansoni / Q000201:enzymology*; D013379:Substrate Specificity
D007527:Isoenzymes; D005982:Glutathione Transferase