{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T15:54:09Z","timestamp":1785426849239,"version":"3.56.0"},"posted":{"date-parts":[[2026,4,14]]},"group-title":"Biophysics","reference-count":43,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,4,14]],"date-time":"2026-04-14T00:00:00Z","timestamp":1776124800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/"}],"funder":[{"award":["1ZIADK029061"],"award-info":[{"award-number":["1ZIADK029061"]}],"id":[{"id":"https:\/\/ror.org\/00adh9b73","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,4,14]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  Fibrils formed by 40- and 42-residue amyloid-\u03b2 peptides (A\u03b240 and A\u03b242) are polymorphic, containing molecular structures that vary with growth conditions in ways that are not fully understood. Here we use cryogenic electron microscopy to characterize the structure of rapidly twisting A\u03b240 fibrils, for which the distance between apparent width minima in electron microscope images (\u201ccross-over distances\u201d) is approximately 25 nm. From samples grown under a single set of growth conditions, we obtain high-resolution structures for three different rapidly twisting polymorphs. Although their cross-over distances are similar, the three rapidly twisting polymorphs differ in twist handedness, symmetry, molecular conformations, and intermolecular contacts. Two of the rapidly twisting polymorphs resemble slowly twisting A\u03b240 polymorphs that have been described previously, including polymorphs extracted from brain tissue of Alzheimer\u2019s disease patients or created by seeded growth from amyloid in brain tissue, but with shorter conformationally ordered segments and other specific conformational differences. These results contribute to our understanding of amyloid polymorphism, connections between morphology and molecular structure, and relationships between brain-derived and\n                  <jats:italic>in vitro<\/jats:italic>\n                  -grown fibrils.\n                <\/jats:p>","DOI":"10.64898\/2026.04.10.717728","type":"posted-content","created":{"date-parts":[[2026,4,14]],"date-time":"2026-04-14T17:50:14Z","timestamp":1776189014000},"source":"Crossref","is-referenced-by-count":0,"title":["Polymorphic structures of rapidly twisting 40-residue amyloid-\u03b2 fibrils"],"prefix":"10.64898","author":[{"given":"Motahareh G.","family":"Larimi","sequence":"first","affiliation":[{"name":"Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases National Institutes of Health, Bethesda, MD 20892-0520"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kent R.","family":"Thurber","sequence":"additional","affiliation":[{"name":"Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases National Institutes of Health, Bethesda, MD 20892-0520"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7039-7275","authenticated-orcid":false,"given":"Robert","family":"Tycko","sequence":"additional","affiliation":[{"name":"Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases National Institutes of Health, Bethesda, MD 20892-0520"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026041707351431000_2026.04.10.717728v1.1","doi-asserted-by":"publisher","DOI":"10.1006\/jsbi.2000.4268"},{"key":"2026041707351431000_2026.04.10.717728v1.2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.142459399"},{"key":"2026041707351431000_2026.04.10.717728v1.3","doi-asserted-by":"publisher","DOI":"10.1126\/science.1105850"},{"key":"2026041707351431000_2026.04.10.717728v1.4","doi-asserted-by":"publisher","DOI":"10.1016\/j.jmb.2008.11.005"},{"key":"2026041707351431000_2026.04.10.717728v1.5","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0806270105"},{"key":"2026041707351431000_2026.04.10.717728v1.6","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0506109102"},{"key":"2026041707351431000_2026.04.10.717728v1.7","doi-asserted-by":"publisher","DOI":"10.1021\/bi701427q"},{"key":"2026041707351431000_2026.04.10.717728v1.8","doi-asserted-by":"publisher","DOI":"10.1126\/science.aao2825"},{"key":"2026041707351431000_2026.04.10.717728v1.9","doi-asserted-by":"publisher","DOI":"10.1038\/nature23002"},{"key":"2026041707351431000_2026.04.10.717728v1.10","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-019-12683-8"},{"key":"2026041707351431000_2026.04.10.717728v1.11","doi-asserted-by":"publisher","DOI":"10.1126\/science.abm7285"},{"key":"2026041707351431000_2026.04.10.717728v1.12","doi-asserted-by":"crossref","unstructured":"Yang, Y. , Murzin, A.G. , Peak-Chew, S. , Franco, C. , Garringer, H.J. , Newell, K.L. , Ghetti, B. , Goedert, M. , and Scheres, S.H.W ., Cryo-EM structures of A\u03b240 filaments from the leptomeninges of individuals with Alzheimer\u2019s disease and cerebral amyloid angiopathy. Acta Neuropathol. Commun. 11, 191 (2023).","DOI":"10.1186\/s40478-023-01694-8"},{"key":"2026041707351431000_2026.04.10.717728v1.13","doi-asserted-by":"crossref","first-page":"1297","DOI":"10.1038\/s41467-023-43822-x","article-title":"Cryo-EM structures of lipidic fibrils of amyloid-\u03b2 (1-40)","volume":"15","year":"2024","journal-title":"Nat. Commun"},{"key":"2026041707351431000_2026.04.10.717728v1.14","doi-asserted-by":"crossref","unstructured":"Fu, Z. , Crooks, E.J. , Irizarry, B.A. , Zhu, X.Y. , Chowdhury, S. , Van Nostrand, W.E. , and Smith, S.O ., An electrostatic cluster guides A\u03b240 fibril formation in sporadic and Dutch-type cerebral amyloid angiopathy. J. Struct. 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