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Direct phase determination by entropy maximization and likelihood ranking: status report and perspectives
1MRC Laboratory of Molecular Biology, Cambridge, England.
Acta Crystallographica. Section D, Biological Crystallography
|January 1, 1993
Summary
A novel multisolution phasing method enhances accuracy and sensitivity for macromolecular crystallography. This probabilistic direct method, implemented in BUSTER, improves phase determination for proteins and small molecules.
Area of Science:
- Crystallography
- Structural Biology
- Computational Chemistry
Background:
- Direct methods are crucial for crystal structure determination.
- Extending direct methods to macromolecules presents significant challenges.
- Probabilistic approaches offer potential for improved phase accuracy.
Purpose of the Study:
- To develop and implement a new multisolution phasing method for macromolecules.
- To enhance the accuracy and sensitivity of probabilistic phase indications.
- To integrate this method into existing macromolecular phasing techniques.
Main Methods:
- Entropy maximization and likelihood ranking for phase set generation and scoring.
- Tree-directed search through phase space.
- Error-correcting codes for efficient phase sampling.
- Statistical analysis for reliable phase selection.
Main Results:
- The new method successfully determined small crystal structures from various diffraction data types.
- Ab initio phasing of small proteins and improvement of low-resolution phases were achieved.
- Demonstrated increased accuracy and sensitivity compared to conventional direct methods.
Conclusions:
- The implemented method effectively extends probabilistic direct methods to macromolecules.
- It addresses key obstructions in ab initio phasing, such as phase sampling errors.
- This Bayesian approach advances integrated and dependable macromolecular phasing.