Direct observation of protein structural transitions through entire amyloid aggregation processes in water using 2D-IR spectroscopy

So Yeon Chun, Myung Kook Son, Chae Ri Park, Chaiho Lim, Hugh I. Kim, Kyungwon Kwak, Minhaeng Cho

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11 Citations (Scopus)

Abstract

Amyloid proteins that undergo self-assembly to form insoluble fibrillar aggregates have attracted much attention due to their role in biological and pathological significance in amyloidosis. This study aims to understand the amyloid aggregation dynamics of insulin (INS) in H2O using two-dimensional infrared (2D-IR) spectroscopy. Conventional IR studies have been performed in D2O to avoid spectral congestion despite distinct H-D isotope effects. We observed a slowdown of the INS fibrillation process in D2O compared to that in H2O. The 2D-IR results reveal that different quaternary structures of INS at the onset of the nucleation phase caused the distinct fibrillation pathways of INS in H2O and D2O. A few different biophysical analysis, including solution-phase small-angle X-ray scattering combined with molecular dynamics simulations and other spectroscopic techniques, support our 2D-IR investigation results, providing insight into mechanistic details of distinct structural transition dynamics of INS in water. We found the delayed structural transition in D2O is due to the kinetic isotope effect at an early stage of fibrillation of INS in D2O, i.e., enhanced dimer formation of INS in D2O. Our 2D-IR and biophysical analysis provide insight into mechanistic details of structural transition dynamics of INS in water. This study demonstrates an innovative 2D-IR approach for studying protein dynamics in H2O, which will open the way for observing protein dynamics under biological conditions without IR spectroscopic interference by water vibrations.

Original languageEnglish
JournalChemical Science
DOIs
Publication statusAccepted/In press - 2022

Bibliographical note

Funding Information:
This research was supported by a grant from the Institute for Basic Science (IBS-R023-D1) and by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (NRF-2020R1A5A1019141). This research was also supported by the Korea Basic Science Institute (KBSI) National Research Facilities & Equipment Center (NFEC), funded by the Korean government (Ministry of Education) (2019R1A6C1010028). This work was also supported by Basic Research Program No. 2019R1H1A2079867 and No. 2019R1A2C2086193 through the National Research Foundation (NRF) of Korea, funded by the Ministry of Science, ICT, and Future Planning (MSIP). This work was also supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (2021R1A4A1032114). The synchrotron X-ray scattering measurements at the 4C SAXS II beamline of the Pohang Accelerator Laboratory were supported by the Ministry of Education and Science Technology. The authors thank the National Center for Seoul National University Research Facilities for their assistance with the TEM measurements.

Publisher Copyright:
© 2022 The Royal Society of Chemistry

ASJC Scopus subject areas

  • General Chemistry

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