{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,28]],"date-time":"2026-03-28T07:16:57Z","timestamp":1774682217265,"version":"3.50.1"},"reference-count":48,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2024,8,31]],"date-time":"2024-08-31T00:00:00Z","timestamp":1725062400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/04046\/2020"],"award-info":[{"award-number":["UIDB\/04046\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDP\/04046\/2020"],"award-info":[{"award-number":["UIDP\/04046\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["GA 101079147"],"award-info":[{"award-number":["GA 101079147"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"name":"European Union","award":["UIDB\/04046\/2020"],"award-info":[{"award-number":["UIDB\/04046\/2020"]}]},{"name":"European Union","award":["UIDP\/04046\/2020"],"award-info":[{"award-number":["UIDP\/04046\/2020"]}]},{"name":"European Union","award":["GA 101079147"],"award-info":[{"award-number":["GA 101079147"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biomolecules"],"abstract":"<jats:p>Atomic force microscopy (AFM) imaging enables the visualization of protein molecules with high resolution, providing insights into their shape, size, and surface topography. Here, we use AFM to study the aggregation process of protein S100A9 in physiological conditions, in the presence of calcium at a molar ratio 4Ca2+:S100A9. We find that S100A9 readily assembles into a worm-like fibril, with a period dimension along the fibril axis of 11.5 nm. The fibril\u2019s chain length extends up to 136 periods after an incubation time of 144 h. At room temperature, the fibril\u2019s bending stiffness was found to be 2.95\u00d710\u221228 Nm2, indicating that the fibrils are relatively flexible. Additionally, the values obtained for the Young\u2019s modulus (Ex=6.96\u00d7105 Pa and Ey=3.37\u00d7105 Pa) are four orders of magnitude lower than those typically reported for canonical amyloid fibrils. Our findings suggest that, under the investigated conditions, a distinct aggregation mechanism may be in place in the presence of calcium. Therefore, the findings reported here could have implications for the field of biomedicine, particularly with regard to Alzheimer\u2019s disease.<\/jats:p>","DOI":"10.3390\/biom14091091","type":"journal-article","created":{"date-parts":[[2024,9,2]],"date-time":"2024-09-02T03:45:21Z","timestamp":1725248721000},"page":"1091","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":37,"title":["Morphological and Biophysical Study of S100A9 Protein Fibrils by Atomic Force Microscopy Imaging and Nanomechanical Analysis"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2654-6848","authenticated-orcid":false,"given":"Ana P.","family":"Carapeto","sequence":"first","affiliation":[{"name":"BioISI\u2014Biosystems and Integrative Sciences Institute, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal"},{"name":"Departamento de F\u00edsica, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal"}]},{"given":"Carlos","family":"Marcuello","sequence":"additional","affiliation":[{"name":"BioISI\u2014Biosystems and Integrative Sciences Institute, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal"},{"name":"Biofisika Institute (CSIC, UPV\/EHU), 48940 Leioa, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2493-2748","authenticated-orcid":false,"given":"Patr\u00edcia F. N.","family":"Fa\u00edsca","sequence":"additional","affiliation":[{"name":"BioISI\u2014Biosystems and Integrative Sciences Institute, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal"},{"name":"Departamento de F\u00edsica, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0468-1910","authenticated-orcid":false,"given":"M\u00e1rio S.","family":"Rodrigues","sequence":"additional","affiliation":[{"name":"BioISI\u2014Biosystems and Integrative Sciences Institute, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal"},{"name":"Departamento de F\u00edsica, Faculdade de Ci\u00eancias, Universidade de Lisboa, Campo Grande, 1749-016 Lisbon, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2024,8,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"930","DOI":"10.1103\/PhysRevLett.56.930","article-title":"Atomic force microscope","volume":"56","author":"Binnig","year":"1986","journal-title":"Phys. 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