β 2 -Type Amyloidlike Fibrils of Poly- l -glutamic Acid Convert into Long, Highly Ordered Helices upon Dissolution in Dimethyl Sulfoxide
| Autor: | Agnieszka Hernik-Magoń, Sylwia Berbeć, Dmitri I. Svergun, Christian Johannessen, Robert Dec, Agnieszka Bzowska, Fernando Tobias, Timothy A. Keiderling, Wojciech Dzwolak, Grzegorz Ścibisz, Beata Wielgus-Kutrowska, Dmitry S. Molodenskiy |
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| Jazyk: | angličtina |
| Předmět: |
chemistry.chemical_classification
010405 organic chemistry Globular protein Dimethyl sulfoxide Infrared spectroscopy macromolecular substances 010402 general chemistry Fibril 01 natural sciences Acceptor 0104 chemical sciences Surfaces Coatings and Films Solvent Chemistry Crystallography chemistry.chemical_compound chemistry Vibrational circular dichroism Materials Chemistry Raman optical activity Physical and Theoretical Chemistry |
| Zdroj: | The Journal of Physical Chemistry B The journal of physical chemistry : B : condensed matter, materials, surfaces, interfaces and biophysical |
| ISSN: | 1520-5207 1520-6106 |
| DOI: | 10.1021/acs.jpcb.8b08308 |
| Popis: | Replacing water with dimethyl sulfoxide (DMSO) completely reshapes the free-energy landscapes of solvated proteins. In DMSO, a powerful hydrogen-bond (HB) acceptor, formation of HBs between backbone NH groups and solvent is favored over HBs involving proteins carbonyl groups. This entails a profound structural disruption of globular proteins and proteinaceous aggregates (e.g., amyloid fibrils) upon transfer to DMSO. Here, we investigate an unusual DMSO-induced conformational transition of β2-amyloid fibrils from poly-l-glutamic acid (PLGA). The infrared spectra of β2-PLGA dissolved in DMSO lack the typical features associated with disordered conformation that are observed when amyloid fibrils from other proteins are dispersed in DMSO. Instead, the frequency and unusual narrowness of the amide I band imply the presence of highly ordered helical structures, which is supported by complementary methods, including vibrational circular dichroism and Raman optical activity. We argue that the conformation most consistent with the spectroscopic data is that of a PLGA chain essentially lacking nonhelical segments such as bends that would provide DMSO acceptors with direct access to the backbone. A structural study of DMSO-dissolved β2-PLGA by synchrotron small-angle X-ray scattering reveals the presence of long uninterrupted helices lending direct support to this hypothesis. Our study highlights the dramatic effects that solvation may have on conformational transitions of large polypeptide assemblies. |
| Databáze: | OpenAIRE |
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