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The amide I spectru...
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Baronio, Cesare M.Stockholms universitet,Institutionen för biokemi och biofysik
(author)
The amide I spectrum of parallel β-sheet proteins
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LIBRIS-ID:oai:DiVA.org:su-179658
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https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-179658URI
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Language:English
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Summary in:English
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Subject category:vet swepub-contenttype
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Subject category:ovr swepub-publicationtype
Notes
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The amide I absorption of the polypeptide backbone has long been used to analyze the secondary structure of proteins. This approach has gained additional attention in the context of amyloid diseases where a particular focus is on the distinction between parallel and antiparallel β-sheets because these structures often discriminate between pre-fibrillar structures and fibrils. Some earlier infrared spectra with typical features of antiparallel β-sheets were interpreted as arising from the parallel β-sheets of fibrils. Therefore, the ability of infrared spectroscopy to distinguish between both types of β-sheets is debated. While it is established that regular, antiparallel β-sheets give rise to a high wavenumber band near 1690 cm-1, it is less clear whether or not this band may also occur for parallel β-sheets. Here we present and analyze the amide I spectra of two β-helix proteins, SV2 and Pent. The overall shape of the proteins is that of a cuboid which has parallel β-sheets on its four sides, which are connected by bends. The main features of their amide I spectrum are a band at 1665, and two bands between 1645 and 1628 cm-1. Both proteins exhibit also a weak component band near 1690 cm-1. Calculations of the amide I spectrum indicate that the absorption at high wavenumbers is not caused by the parallel β-sheets but by the bends between the β-strands. We therefore suggest to modify the interpretation of the amide I spectrum as follows: a high wavenumber band near 1690 cm-1 may be caused by other structures than antiparallel β-sheets. However, when the spectrum consists of only two distinct bands, one near 1690 cm-1 and one near 1630 cm-1, then an assignment to antiparallel β-sheets is consistent with the literature.
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Li, HuiminStockholms universitet,Institutionen för biokemi och biofysik
(author)
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Song, GuangyuanStockholms universitet,Institutionen för biokemi och biofysik
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Annecke, HenryStockholms universitet,Institutionen för biokemi och biofysik(Swepub:su)hean3705
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Gustafsson, RobertStockholms universitet,Institutionen för biokemi och biofysik
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Martinez-Carranza, MarkelStockholms universitet,Institutionen för biokemi och biofysik(Swepub:su)mama6974
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Stenmark, PålStockholms universitet,Institutionen för biokemi och biofysik(Swepub:su)stenm
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Barth, AndreasStockholms universitet,Institutionen för biokemi och biofysik(Swepub:su)abart
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Stockholms universitetInstitutionen för biokemi och biofysik
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