Responses of glutathione-related enzymes in isolated rat small intestine to Fe(2+)-EDTA-mediated oxidative stress.
The activities of glutathione-related enzymes in isolated rat small intestine were investigated under oxidative stress mediated by Fe(2+)-EDTA. The isoelectric points and approximate molecular weights of the enzymes investigated were first determined. The reduced and oxidized glutathione contents, and low molecular weight thiols in isolated rat small intestine were also studied under oxidative stress. Significant reducing activities of glutathione S-transferase and lactate dehydrogenase were observed accompanied by increases in oxidized glutathione content, whereas thioltransferase, glutathione reductase, glutathione peroxidase and thioredoxin reductase retained the same levels of activity as controls. First-order inactivation of purified rat small intestine glutathione S-transferase including class-alpha, mu and pi was observed and the isozyme class-pi was inactivated at several pH's under Fe(2+)-EDTA-mediated oxidative stress. Leakage of protein and both reduced and oxidized forms of glutathione was significantly increased during incubation with Fe(2+)-EDTA. In conclusion, enzymes which were not inactivated under Fe(2+)-EDTA-mediated oxidative stress may play an important role in cellular antioxidant defenses in the small intestine. Furthermore, enzymes such as glutathione S-transferase, mainly a class-pi isozyme, and lactate dehydrogenase which were inactivated may form part of the barrier against oxidative stress similar to reduced glutathione.
Mizoguchi
T
T
Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Osaka University, Japan.
Morita
Y
Y
Nanjo
H
H
Terada
T
T
Nishihara
T
T
D000818:Animals; D004492:Edetic Acid / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D007421:Intestine, Small / Q000187:drug effects / Q000201:enzymology*; D007525:Isoelectric Focusing; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008970:Molecular Weight; D018384:Oxidative Stress; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000139:chemically induced / Q000201:enzymology*
D011506:Proteins; D004492:Edetic Acid; D007770:L-Lactate Dehydrogenase; D005982:Glutathione Transferase; D005978:Glutathione