tailieunhanh - 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 mass¼ and 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@ Website http bwillmor Received 28 March 05 revised 17 May 05 accepted 20 May 05 doi 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 and 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 and 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 .

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