Temperature-induced changes in protein structures studied by Fourier transform infrared spectroscopy and global...

Area of Science:

• Biochemistry
• Spectroscopy
• Protein Chemistry

Background:

• Proteins undergo structural changes with temperature variations.
• Understanding these changes is crucial for protein stability and function.
• Heavy water (2H2O) can influence protein hydrogen-deuterium exchange dynamics.

Purpose of the Study:

• To investigate temperature-induced structural alterations in various proteins using FTIR spectroscopy.
• To develop and apply a novel global data analysis method for spectral analysis.
• To determine the thermal stability and aggregation behavior of proteins in 2H2O.

Main Methods:

• Fourier transform infrared (FTIR) spectroscopy was employed to monitor proteins in 2H2O.
• A new global spectral analysis method using a spectral model was developed.
• Sigmoidal band amplitude curves were fitted with a two-state thermodynamic model.

Main Results:

• FTIR spectra were analyzed globally, fitting data with 7-8 bands (1420-1760 cm-1) with high accuracy.
• Enhanced 1H-2H exchange occurred below secondary structure unfolding, indicating tertiary structure changes and increased solvent accessibility.
• Except for ribonuclease S, aggregation (intermolecular beta-sheet band) coincided with secondary structure denaturation.

Conclusions:

• The study provides insights into protein structural changes and thermal stability using FTIR spectroscopy in 2H2O.
• A novel global analysis approach enhances the interpretation of complex spectral data.
• Protein aggregation is linked to secondary structure denaturation, with variations observed among different proteins.