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Low-resolution real-space envelopes: an approach to the ab initio macromolecular phase problem
1Beckman Laboratories for Structural Biology, Department of Cell Biology, Stanford University School of Medicine, CA 94305.
Science (New York, N.Y.)
|April 5, 1991
Summary
This study introduces a novel ab initio method for solving the phase problem in macromolecular X-ray crystallography. The approach models solvent regions, providing low-resolution structures that can be refined to higher resolutions.
Area of Science:
- Crystallography
- Structural Biology
- Biophysics
Background:
- The phase problem is a major hurdle in macromolecular X-ray crystallography, limiting structure determination.
- Accurate phase information is crucial for reconstructing electron density maps and solving molecular structures.
Purpose of the Study:
- To develop an ab initio computational method to address the phase problem in macromolecular crystallography.
- To generate initial low-resolution structural information from diffraction data.
Main Methods:
- A computational model simulating a random gas of hard-sphere point scatterers condensing under crystallographic constraints.
- Incorporation of solvent fraction and observed Fourier amplitude data to guide the condensation process.
- Application of the method to real macromolecular datasets.
Main Results:
- The method successfully generates an approximate outline of bulk solvent regions within the unit cell.
- This yields a low-resolution electron density map, providing initial structural insights.
- Demonstrated applicability to real macromolecular examples.
Conclusions:
- The ab initio approach offers a viable strategy for tackling the phase problem, particularly for low-resolution data.
- The generated low-resolution models can serve as a starting point for phase extension techniques like molecular replacement or non-crystallographic symmetry.
- This method enhances the accessibility of macromolecular structure determination.