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In Situ Identification of Secondary Structures in Unpurified Bombyx mori Silk Fibrils Using Polarized Two-Dimensional
Giulia Giubertoni1,2, Federico Caporaletti1,2, Steven J Roeters1,3
1Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XHAmsterdam, The Netherlands.
Biomacromolecules
|November 28, 2022
Summary
Polarized two-dimensional infrared spectroscopy (2D-IR) reveals silk
Area of Science:
- Biomaterials Science
- Spectroscopy
- Protein Chemistry
Background:
- Biomaterial mechanical properties depend on protein structure.
- Understanding protein molecular properties is crucial but challenging.
- Infrared spectroscopy analyzes protein secondary structure via amide bands, but spectral congestion limits analysis.
Purpose of the Study:
- To apply polarized 2D-IR spectroscopy to characterize protein secondary structures in Bombyx mori silk films.
- To investigate the effects of hydration on silk secondary structures without spectral deconvolution.
Main Methods:
- Utilized polarized two-dimensional infrared (2D-IR) spectroscopy.
- Analyzed native silk films derived from Bombyx mori silk feedstock.
- Directly identified protein secondary structures without peak fitting.
Main Results:
- Observed an initial increase in random coil content upon hydration, with a concurrent decrease in helical content.
- Found that beta-sheet content remained unchanged initially, increasing only at a later hydration stage.
- Demonstrated direct identification of secondary structures without additional spectral fitting.
Conclusions:
- Polarized 2D-IR spectroscopy is effective for characterizing biomaterials.
- Hydration significantly alters silk secondary structures, impacting protein conformations.
- The study provides direct insights into silk's structural response to hydration.
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