Protein Electrostatics Investigated through Paramagnetic NMR for Nonpolar Groups

Area of Science:

• Biophysics
• Structural Biology
• Computational Chemistry

Background:

• Experimental validation of theoretical protein electrostatics models is limited.
• Accurate electrostatic models are crucial for understanding protein function and interactions.
• Previous methods for validation are often indirect or provide limited data points.

Purpose of the Study:

• To expand a paramagnetic NMR-based method for determining effective near-surface electrostatic potentials.
• To experimentally validate theoretical electrostatic models for proteins using this novel approach.
• To assess the influence of protein structural dynamics on electrostatic potential measurements.

Main Methods:

• Utilized ¹H paramagnetic relaxation enhancement (PRE) data from protein C_αH and CH₃ groups.
• Developed a de novo method for determining effective near-surface electrostatic potentials.
• Compared experimental PRE data with predictions from the Poisson-Boltzmann theory.

Main Results:

• Successfully determined effective near-surface electrostatic potentials from ¹H PRE data.
• Demonstrated good agreement between experimental data and Poisson-Boltzmann predictions, especially for methyl ¹H nuclei.
• Showcased the method's ability to provide a significantly larger dataset for model validation compared to pK_a-based approaches.

Conclusions:

• The paramagnetic NMR-based method offers a robust and direct approach for validating protein electrostatic models.
• This technique provides a wealth of experimental data, enhancing our ability to refine theoretical electrostatic predictions.
• The findings contribute to a better understanding of protein electrostatics and its role in biomolecular function.