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Multiresolution phase extension of a trypsin inhibitor structure from 5 A to 2 A based on diffraction amplitudes
1Department of Physics, University of Houston, Houston, Texas 77204, USA.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 13, 2009
Summary
A new multiresolution refinement procedure accurately determines over 80% of 2 Angstrom (Å) phases for trypsin inhibitor structures. This method enhances crystallographic phase determination by utilizing reflection amplitudes in both real and reciprocal spaces.
Area of Science:
- Crystallography
- Structural Biology
- Biochemistry
Background:
- Accurate determination of crystallographic phases is crucial for solving protein structures.
- Extending phase information from lower to higher resolutions presents significant challenges in macromolecular crystallography.
Purpose of the Study:
- To develop and validate a novel multiresolution refinement procedure for improving crystallographic phase accuracy.
- To enhance the determination of 2 Å resolution phases for a specific trypsin inhibitor structure.
Main Methods:
- Application of a multiresolution refinement procedure starting from a 5 Å phase set.
- Refinement process conducted in both real and reciprocal spaces.
- Utilization of reflection amplitudes in Fourier synthesis and real-space density modifications.
Main Results:
- Approximately 80% of the 2 Å phases were correctly determined within an 18-degree error.
- Successful extension of structural information from 5 Å to 2 Å resolution.
- Demonstrated effectiveness of using amplitudes in real-space density modifications.
Conclusions:
- The multiresolution refinement procedure offers a robust method for enhancing crystallographic phase determination.
- This technique improves the accuracy and completeness of high-resolution structural data.
- The approach provides an alternative to conventional phase extension schemes by incorporating amplitude information more effectively.
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