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Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR
Published on: December 16, 2013
Comparison of ring current methods for use in molecular modeling refinement of NMR derived three-dimensional
G Moyna1, R J Zauhar, H J Williams
1Department of Chemistry, Texas A&M University, College Station 77842-3012, USA.
Journal of Chemical Information and Computer Sciences
|August 6, 1998
Summary
This study compares three methods for estimating ring current effects on protein chemical shifts. The classical point-dipole model, when updated with quantum-mechanical data, shows improved accuracy for NMR structure refinement.
Area of Science:
- Biophysical Chemistry
- Structural Biology
- Nuclear Magnetic Resonance (NMR) Spectroscopy
Background:
- Estimating ring current effects is crucial for accurate chemical shift prediction in proteins.
- Existing methods like Haigh-Mallion, Johnson-Bovey, and classical point-dipole approximations have varying degrees of accuracy and applicability.
- Accurate chemical shift analysis aids in protein structure determination and refinement.
Purpose of the Study:
- To compare the accuracy of three common methods for estimating protein ring current effects on chemical shifts.
- To re-evaluate and improve the classical point-dipole approximation using quantum-mechanical data.
- To assess the utility of these methods, particularly the improved point-dipole model, for NMR-based protein structure refinement.
Main Methods:
- Applied Haigh-Mallion, Johnson-Bovey, and classical point-dipole models to calculate ring current contributions for protein protons.
- Derived new proportionality constants for the classical point-dipole model by fitting to Haigh-Mallion and Johnson-Bovey estimations.
- Utilized protein crystal structures and chemical shift assignments for comparative analysis.
Main Results:
- The classical point-dipole approximation, when parametrized with quantum-mechanical data, demonstrated superior performance compared to the traditional Perkins and Dwek constant.
- This improved point-dipole model showed comparable accuracy to the Johnson-Bovey method and was slightly less accurate than the Haigh-Mallion theory.
- A pseudoenergy penalty term based on the improved classical point-dipole model was successfully implemented for structure refinement.
Conclusions:
- Parametrizing the classical point-dipole model with quantum-mechanical data significantly enhances its predictive power for ring current effects on chemical shifts.
- The improved classical point-dipole model offers a viable and computationally efficient alternative for NMR structure refinement, especially when other NMR data is scarce.
- This work provides a refined approach to chemical shift analysis, contributing to more accurate protein structure determination using NMR spectroscopy.
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