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Báo cáo khoa học: Purification and properties of the glutathione S-transferases from the anoxia-tolerant turtle, Trachemys scripta elegans

GlutathioneS-transferases (GSTs) play critical roles in detoxification, response to oxidative stress, regeneration of S-thiolated proteins, and cata-lysis of reactions in nondetoxification metabolic pathways. Liver GSTs were purified from the anoxia-tolerant turtle,Trachemys scripta elegans. Purification separated a homodimeric (subunit relative molecular mass¼ 34 kDa) and a heterodimeric (subunit relative molecular mass¼32.6 and 36.8 kDa) form of GST. | iFEBS Journal Purification and properties of the glutathione S-transferases from the anoxia-tolerant turtle Trachemys scripta elegans William G. Willmore and Kenneth B. Storey Institute of Biochemistry Carleton University Ottawa Ontario Canada Keywords Adaptation anoxia glutathione S-transferases turtle Correspondence W. G. Willmore Institute of Biochemistry Carleton University Ottawa Ontario K1S 5B6 Canada Fax 01 613 520 3539 Tel 01 613 520 2600 ext. 1211 E-mail Bill_Willmore@carleton.ca Website http www.carleton.ca bwillmor Received 28 March 05 revised 17 May 05 accepted 20 May 05 doi 10.1111 j.1742-4658.2005.04783.x Glutathione S-transferases GSTs play critical roles in detoxification response to oxidative stress regeneration of S-thiolated proteins and catalysis of reactions in nondetoxification metabolic pathways. Liver GSTs were purified from the anoxia-tolerant turtle Trachemys scripta elegans. Purification separated a homodimeric subunit relative molecular mass 34 kDa and a heterodimeric subunit relative molecular mass 32.6 and 36.8 kDa form of GST. The enzymes were purified 23-69-fold and 156174-fold for homodimeric and heterodimeric GSTs respectively. Kinetic data gathered using a variety of substrates and inhibitors suggested that both homodimeric and heterodimeric GSTs were of the a class although they showed significant differences in substrate affinities and responses to inhibitors. For example homodimeric GST showed activity with known a class substrates cumene hydroperoxide and p-nitrobenzylchloride whereas heterodimeric GST showed no activity with cumene hydroperoxide. The specific activity of liver GSTs with chlorodinitrobenzene CDNB as the substrate was reduced by 2.6- and 8.7-fold for homodimeric and heterodimeric GSTs isolated from liver of anoxic turtles as compared with aerobic controls suggesting an anoxia-responsive stable modification of the protein that may alter its function during natural anaerobiosis. The glutathione S-transferases .