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Amyloids are insoluble fibrous protein aggregates sharing specific structural traits. They are insoluble and arise from at least 18 inappropriately folded versions of proteins and polypeptides present naturally in the body. These misfolded structures alter their proper configuration such that they erroneously interact with one another or other cell components forming insoluble fibrils. They have been associated with the pathology of more than 20 serious human diseases in that abnormal accumulation of amyloid fibrils in organs may lead to amyloidosis, and may play a role in various neurodegenerative disorders. ==Definition== The name ''amyloid'' comes from the early mistaken identification by Rudolf Virchow of the substance as starch (''amylum'' in Latin, from Greek ἄμυλον ''amylon''), based on crude iodine-staining techniques. For a period, the scientific community debated whether or not amyloid deposits are fatty deposits or carbohydrate deposits until it was finally found (in 1859) that they are, in fact, deposits of albumoid proteinaceous material. * The classical, histopathological definition of amyloid is an extracellular, proteinaceous deposit exhibiting beta sheet structure. Common to most cross-beta-type structures, in general, they are identified by apple-green birefringence when stained with congo red and seen under polarized light. These deposits often recruit various sugars and other components such as Serum Amyloid P component, resulting in complex, and sometimes inhomogeneous structures. Recently this definition has come into question as some classic, amyloid species have been observed in distinctly intracellular locations. * A more recent, ''biophysical'' definition is broader, including any polypeptide that polymerizes to form a cross-beta structure, ''in vivo'' or ''in vitro''. Some of these, although demonstrably cross-beta sheet, do not show some classic histopathological characteristics such as the Congo-red birefringence. Microbiologists and biophysicists have largely adopted this definition, leading to some conflict in the biological community over an issue of language. The remainder of this article will use the biophysical context. 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「amyloid」の詳細全文を読む スポンサード リンク
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