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Structural Insight of Amyloidogenic Intermediates of Human Insulin
[Image: see text] Engaging Raman spectroscopy as a primary tool, we investigated the early events of insulin fibrilization and determined the structural content present in oligomer and protofibrils that are formed as intermediates in the fibril formation pathway. Insulin oligomer, as obtained upon i...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical Society
2018
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6045404/ https://www.ncbi.nlm.nih.gov/pubmed/30023834 http://dx.doi.org/10.1021/acsomega.7b01776 |
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author | Dolui, Sandip Roy, Anupam Pal, Uttam Saha, Achintya Maiti, Nakul C. |
author_facet | Dolui, Sandip Roy, Anupam Pal, Uttam Saha, Achintya Maiti, Nakul C. |
author_sort | Dolui, Sandip |
collection | PubMed |
description | [Image: see text] Engaging Raman spectroscopy as a primary tool, we investigated the early events of insulin fibrilization and determined the structural content present in oligomer and protofibrils that are formed as intermediates in the fibril formation pathway. Insulin oligomer, as obtained upon incubation of zinc-free insulin at 60 °C, was mostly spherical in shape, with a diameter of 3–5 nm. Longer incubation produced “necklace”-like beaded protofibrillar assembly species. These intermediates eventually transformed into 5–8 nm thick fibers with smooth surface texture. A broad amide I band in the Raman spectrum of insulin monomer appeared at 1659 cm(–1), with a shoulder band at 1676 cm(–1). This signature suggested the presence of major helical and extended secondary structure of the protein backbone. In the oligomeric state, the protein maintained its helical imprint (∼50%) and no substantial increment of the compact cross-β-sheet structure was observed. A nonamide helix signature band at 940 cm(–1) was present in the oligomeric state, and it was weakened in the fibrillar structure. The 1-anilino-8-naphthalene-sulfonate binding study strongly suggested that a collapse in the tertiary structure, not the major secondary structural realignment, was the dominant factor in the formation of oligomers. In the fibrillar state, the contents of helical and disordered secondary structures decreased significantly and the β-sheet amount increased to ∼62%. The narrow amide I Raman band at 1674 cm(–1) in the fibrillar state connoted the formation of vibrationally restricted highly organized β-sheet structure with quaternary realignment into steric-zipped species. |
format | Online Article Text |
id | pubmed-6045404 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | American Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-60454042018-07-16 Structural Insight of Amyloidogenic Intermediates of Human Insulin Dolui, Sandip Roy, Anupam Pal, Uttam Saha, Achintya Maiti, Nakul C. ACS Omega [Image: see text] Engaging Raman spectroscopy as a primary tool, we investigated the early events of insulin fibrilization and determined the structural content present in oligomer and protofibrils that are formed as intermediates in the fibril formation pathway. Insulin oligomer, as obtained upon incubation of zinc-free insulin at 60 °C, was mostly spherical in shape, with a diameter of 3–5 nm. Longer incubation produced “necklace”-like beaded protofibrillar assembly species. These intermediates eventually transformed into 5–8 nm thick fibers with smooth surface texture. A broad amide I band in the Raman spectrum of insulin monomer appeared at 1659 cm(–1), with a shoulder band at 1676 cm(–1). This signature suggested the presence of major helical and extended secondary structure of the protein backbone. In the oligomeric state, the protein maintained its helical imprint (∼50%) and no substantial increment of the compact cross-β-sheet structure was observed. A nonamide helix signature band at 940 cm(–1) was present in the oligomeric state, and it was weakened in the fibrillar structure. The 1-anilino-8-naphthalene-sulfonate binding study strongly suggested that a collapse in the tertiary structure, not the major secondary structural realignment, was the dominant factor in the formation of oligomers. In the fibrillar state, the contents of helical and disordered secondary structures decreased significantly and the β-sheet amount increased to ∼62%. The narrow amide I Raman band at 1674 cm(–1) in the fibrillar state connoted the formation of vibrationally restricted highly organized β-sheet structure with quaternary realignment into steric-zipped species. American Chemical Society 2018-02-28 /pmc/articles/PMC6045404/ /pubmed/30023834 http://dx.doi.org/10.1021/acsomega.7b01776 Text en Copyright © 2018 American Chemical Society This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes. |
spellingShingle | Dolui, Sandip Roy, Anupam Pal, Uttam Saha, Achintya Maiti, Nakul C. Structural Insight of Amyloidogenic Intermediates of Human Insulin |
title | Structural Insight of Amyloidogenic Intermediates
of Human Insulin |
title_full | Structural Insight of Amyloidogenic Intermediates
of Human Insulin |
title_fullStr | Structural Insight of Amyloidogenic Intermediates
of Human Insulin |
title_full_unstemmed | Structural Insight of Amyloidogenic Intermediates
of Human Insulin |
title_short | Structural Insight of Amyloidogenic Intermediates
of Human Insulin |
title_sort | structural insight of amyloidogenic intermediates
of human insulin |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6045404/ https://www.ncbi.nlm.nih.gov/pubmed/30023834 http://dx.doi.org/10.1021/acsomega.7b01776 |
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