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Optimizing the hydrogen-bond network in Poisson-Boltzmann equation-based pK(a) calculations
1European Molecular Biology Laboratory, Heidelberg, Germany. nielsen@embl-heidelberg.de
Proteins
|May 8, 2001
Summary
Accurate protein pK(a) calculations are improved by globally optimizing hydrogen-bond networks. This method enhances precision, especially for buried residues, and highlights the need to correct crystal packing artifacts in structural data.
Area of Science:
- Computational chemistry
- Biophysics
- Structural biology
Background:
- Poisson-Boltzmann equation (FDPB) methods are crucial for calculating protein pK(a) values.
- Current FDPB methods often involve localized adjustments to protonation states, potentially limiting accuracy.
- Crystal packing artifacts can introduce significant errors into pK(a) predictions.
Purpose of the Study:
- To develop an improved FDPB-based pK(a) calculation method.
- To enhance the accuracy of pK(a) predictions, particularly for challenging residues.
- To address the impact of structural artifacts on pK(a) calculations.
Main Methods:
- Implemented a finite difference Poisson-Boltzmann (FDPB) approach.
- Introduced global optimization of the hydrogen-bond network for each protonation state.
- Analyzed the influence of crystal packing on protein structures.
Main Results:
- The novel method significantly improves the accuracy of calculated pK(a) values.
- Global hydrogen-bond network optimization is especially beneficial for buried protein residues.
- Crystal packing artifacts were identified as a major source of error in pK(a) predictions.
Conclusions:
- Global hydrogen-bond network optimization represents a substantial advancement in FDPB-based pK(a) calculations.
- Accurate pK(a) prediction necessitates the use of crystal structures corrected for packing artifacts.
- Future force field optimization should prioritize crystal artifact-corrected X-ray structures.