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Thiol cofactors for selenoenzymes and their synthetic mimics

Sarma, Bani Kanta and Mugeshii, Govindasamy (2008) Thiol cofactors for selenoenzymes and their synthetic mimics. In: Organic and Biomolecular Chemistry, 6 (6). pp. 965-974.

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The importance of selenium as an essential trace element is now well recognized. In proteins, the redox-active selenium moiety is incorporated as selenocysteine (Sec), the 21st amino acid. In mammals, selenium exerts its redox activities through several selenocysteine-containing enzymes, which include glutathione peroxidase (GPx), iodothyronine deiodinase (ID), and thioredoxin reductase (TrxR). Although these enzymes have Sec in their active sites, they catalyze completely different reactions and their substrate specificity and cofactor or co-substrate systems are significantly different. The antioxidant enzyme GPx uses the tripeptide glutathione (GSH) for the catalytic reduction of hydrogen peroxide and organic peroxides, whereas the larger and more advanced mammalian TrxRs have cysteine moieties in different subunits and prefer to utilize these internal cysteines as thiol cofactors for their catalytic activity. On the other hand, the nature of in vivo cofactor for the deiodinating enzyme ID is not known, although the use of thiols as reducing agents has been well-documented. Recent studies suggest that molecular recognition and effective binding of the thiol cofactors at the active site of the selenoenzymes and their mimics play crucial roles in the catalytic activity. The aim of this perspective is to present an overview of the thiol cofactor systems used by different selenoenzymes and their mimics.

Item Type: Journal Article
Publication: Organic and Biomolecular Chemistry
Publisher: Royal Society of Chemistry
Additional Information: Copyright of this article belongs to Royal Society of Chemistry.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 04 Jun 2010 05:41
Last Modified: 19 Sep 2010 05:59
URI: http://eprints.iisc.ac.in/id/eprint/26826

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