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Combining experimental information from crystal and solution studies: joint X-ray and NMR refinement.
B Shaanan1, A M Gronenborn, G H Cohen
1Laborator of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
Science (New York, N.Y.)
|August 14, 1992
Summary
This study introduces joint refinement, combining X-ray crystallography and nuclear magnetic resonance (NMR) data for improved macromolecular models. This integrated approach enhances structural accuracy and identifies crystal versus solution structure differences.
Area of Science:
- Structural biology
- Biophysics
- Computational biology
Background:
- Macromolecular structure determination often relies on X-ray crystallography or Nuclear Magnetic Resonance (NMR) spectroscopy.
- Each technique provides complementary information but also has limitations.
- Integrating data can yield more accurate and comprehensive structural models.
Purpose of the Study:
- To present a method for joint refinement of macromolecular structures using both crystallographic and NMR data.
- To demonstrate the utility of this method using the interleukin-1 beta protein model.
- To highlight the potential for resolving structural ambiguities in complex proteins.
Main Methods:
- Development and application of a joint refinement protocol integrating X-ray diffraction and NMR observational data.
- Modeling of the interleukin-1 beta protein using the combined dataset.
- Comparison of the resulting model's quality against conventional crystallographic models and experimental data.
Main Results:
- The joint refinement produced a model of interleukin-1 beta consistent with both X-ray and NMR observations.
- The model exhibited crystallographic R-values and geometric parameters comparable to or better than conventionally refined models.
- Discrepancies between the model and NMR data indicated genuine differences between crystal and solution structures.
Conclusions:
- Joint X-ray and NMR refinement is a powerful strategy for enhancing macromolecular structural models.
- This integrated approach improves accuracy and can resolve ambiguities, particularly in multidomain proteins.
- The method effectively identifies biologically relevant structural variations between crystalline and solution states.
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