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Three Conformations of Polyglutamic Acid Monitored by Vibrational Optical Activity
Andrii S Kurochka1, Jana Hudecová2, Josef Kapitán2
1Institute of Organic Chemistry and Biochemistry, Academy of Sciences, Flemingovo Náměstí 2, 16610 Prague, Czech Republic.
Analytical Chemistry
|December 12, 2025
Summary
Polyglutamic acid (PGA) folding was studied using vibrational optical activity. This technique, combined with computational methods, offers a powerful way to analyze protein structure, including amyloid fibrils.
Area of Science:
- Biophysics
- Spectroscopy
- Computational Chemistry
Background:
- Polyglutamic acid (PGA) serves as a model for peptide and protein folding studies.
- Vibrational optical activity (VOA) is a key technique for analyzing molecular conformation in solution.
Purpose of the Study:
- To investigate PGA behavior across different protonation states.
- To advance spectroscopic methodologies for protein structure analysis.
- To explore the VOA of PGA fibrils.
Main Methods:
- Acquisition of infrared (IR), vibrational circular dichroism (VCD), Raman, and Raman optical activity (ROA) spectra.
- Molecular dynamics (MD) and density functional theory (DFT) computations for spectral interpretation.
- Measurement of ROA spectra for both PGA enantiomers and fibrils.
Main Results:
- Distinct ROA patterns were observed for PGA fibrils, verifiable with both enantiomers.
- Computational models successfully linked spectral features to molecular geometry.
- Simulated spectra largely reproduced experimental data, despite challenges in fibril VOA simulation.
Conclusions:
- VOA combined with spectral simulations is an effective tool for studying protein geometry, including aggregates like amyloid fibrils.
- Advancements in VOA for amyloid fibrils could enhance understanding of their biological roles in neurodegenerative diseases.
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