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|Section2= }} Ergothioneine is a naturally occurring amino acid and is a thiourea derivative of histidine, containing a sulfur atom on the imidazole ring. This compound is made in rather few organisms, notably Actinobacteria, Cyanobacteria, and certain fungi. Ergothioneine was discovered in 1909 and named after the ergot fungus from which it was first purified, with its structure being determined later, in 1911.〔 This amino acid has antioxidant properties, but its chemistry differs from conventional sulfur-containing antioxidants such as glutathione or lipoic acid. Although ergothioneine cannot be made in human cells, it is present in some tissues at high levels as it is absorbed from the diet. In humans ergothioneine is taken up from the gut and concentrated in some tissues by a specific transporter called ETT (gene symbol SLC22A4). However, even today, one hundred years after its discovery, precisely what ergothioneine does in the human body remains a mystery.〔〔 ==Chemistry== Ergothioneine is a thiourea derivative of the betaine of histidine and contains a sulfur atom bonded to the 2-position of the imidazole ring. This compound is unusual since the sulfur atom is most stable in solution in the thione form, rather than the sulfhydryl, as is the case for the structurally related ovothiol. This makes ergothioneine much less reactive than thiols such as glutathione towards alkylating agents like maleimides, and also prevents the compound from oxidizing in air.〔 However, ergothioneine can be slowly oxidized over several days to the disulfide form in acidic solutions. If ergothioneine does become oxidized, the disulfide is a very strong oxidizing agent, so this will in turn rapidly oxidize other thiols in the cell such as glutathione. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ergothioneine」の詳細全文を読む スポンサード リンク
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