Amide proton temperature coefficients as hydrogen bond indicators in proteins

Area of Science:

• Biophysics
• Structural Biology
• Nuclear Magnetic Resonance (NMR) Spectroscopy

Background:

• Hydrogen bonds are crucial for protein structure and function.
• Amide proton temperature coefficients (deltasigmaHN/deltaT) are sensitive to the local environment.

Purpose of the Study:

• To investigate the correlation between amide proton temperature coefficients and hydrogen bonds.
• To establish the predictive power of deltasigmaHN/deltaT for hydrogen bond identification.
• To explore factors influencing deltasigmaHN/deltaT, including secondary structure and ring current effects.

Main Methods:

• Analysis of a dataset of 793 amides from 14 proteins.
• Correlation analysis between deltasigmaHN/deltaT values and hydrogen bond characteristics (length, secondary structure).
• Investigation of the influence of ring current effects and pH on temperature coefficients.

Main Results:

• High predictive value (>85%, >93%) of deltasigmaHN/deltaT for hydrogen bonds was observed.
• An inverse relationship was found between deltasigmaHN/deltaT and hydrogen bond length.
• Differences in deltasigmaHN/deltaT were noted between alpha-helices and beta-sheets, influenced by hydrogen bond lengths.
• Ring current effects significantly impact deltasigmaHN/deltaT for non-hydrogen bonded amides.
• Temperature coefficients are generally stable with pH, except during conformational changes.

Conclusions:

• Amide proton temperature coefficients provide a reliable and straightforward method for confirming hydrogen bonds in NMR-determined protein structures.
• The study quantifies the relationship between temperature coefficients, hydrogen bond length, and secondary structural elements.
• This approach enhances structural analysis and validation in NMR studies.