Non-merohedral twinning: from minerals to proteins

Area of Science:

• Crystallography
• Structural Biology
• Materials Science

Background:

• Non-merohedral twinning presents challenges in X-ray diffraction data processing due to non-overlapping reciprocal lattices.
• This complexity affects critical steps like unit-cell determination, indexing, data integration, and scaling.

Purpose of the Study:

• To describe a common strategy for solving and refining non-merohedral twins.
• To demonstrate the successful application of this strategy to diverse crystal types.

Main Methods:

• Utilized CELL_NOW for unit-cell constants and orientation matrices.
• Employed SAINT for data integration and TWINABS for scaling and absorption correction.
• Applied experimental phasing (SHELXT, SHELXC/D/E) and refinement (SHELXL).

Main Results:

• Successfully detwinned and refined data for one mineral, one organometallic, and two protein non-merohedral twins.
• Generated separate datasets for initial structure solution and more accurate final refinement.
• Demonstrated the efficacy of the common strategy across different sample types.

Conclusions:

• A unified strategy can effectively address the challenges of non-merohedral twinning in X-ray diffraction.
• The described methods facilitate accurate structure determination and refinement for complex crystal systems.
• This approach enhances the reliability of crystallographic data analysis for diverse molecular and material structures.