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Improving High Viscosity Extrusion of Microcrystals for Time-resolved Serial Femtosecond Crystallography at X-ray Lasers
Published on: February 28, 2019
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Direct phasing of protein crystals with high solvent content
1Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204, USA.
Acta Crystallographica. Section A, Foundations and Advances
|December 25, 2014
Summary
A new iterative method solves the protein crystallography phase problem by creating an estimated protein mask and using solvent flattening. This approach refines electron-density maps and phases for high-resolution protein structures.
Area of Science:
- Crystallography
- Structural Biology
- Biophysics
Background:
- The phase problem is a critical challenge in protein crystallography.
- Accurate phase determination is essential for reconstructing electron-density maps and solving protein structures.
Purpose of the Study:
- To propose an iterative transform method for solving the phase problem in protein crystallography.
- To develop a novel phasing algorithm that enhances traditional refinement tools.
Main Methods:
- An iterative transform method was developed.
- In each iteration, a weighted average electron-density map is used to estimate a protein mask.
- Solvent flattening is applied using the hybrid input-output algorithm.
Main Results:
- The iterative method, starting from random initial phases, converges to correct phase values with an average error of 30-40° for high-resolution data.
- The method demonstrated success with protein crystals exhibiting high solvent content.
- The estimated protein mask evolved to the correct shape after thousands of iterations.
Conclusions:
- The proposed iterative transform method effectively solves the phase problem in protein crystallography.
- The algorithm shows potential for phasing protein crystals with lower solvent fractions (<50%) when combined with non-crystallographic symmetry.
- This new phasing algorithm complements and improves existing refinement techniques.
