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Updated: May 11, 2026
09:27
Protein Crystallization for X-ray Crystallography
Published on: January 16, 2011
Can protein conformers be fractionated by crystallization?
Aoshuang Xu1, Fenglei Li, Howard Robinson
1Ames Laboratory-USDOE and Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Analytical Chemistry
|June 1, 2013
Summary
Molecular crystallization selects specific protein conformations. However, human lactate dehydrogenase isozyme 1 (LDH-1) crystals showed varied activities, revealing crystallization
Area of Science:
- Biochemistry
- Structural Biology
- Biophysics
Background:
- Proteins exist in multiple conformations in solution.
- Molecular crystallization is thought to select a specific protein conformation.
Purpose of the Study:
- To evaluate the conformational selectivity of protein crystallization.
- To investigate the heterogeneity of protein activity at the single-molecule level.
Main Methods:
- Dissolving human lactate dehydrogenase isozyme 1 (LDH-1) microcrystals.
- Enzyme activity assays using electrophoretically mediated microanalysis (EMMA) at ensemble and single-molecule levels.
- X-ray crystallography to analyze protein conformations.
Main Results:
- Enzyme activities were identical within fragments from the same crystal.
- Different crystals exhibited markedly different LDH-1 activities.
- Single molecules from solution showed a 4-fold variation in activity, while molecules from crystals were homogeneous.
- Stored crystal solutions showed broadened activity distributions, approaching that of solution LDH.
Conclusions:
- Crystallization selects specific protein conformations, including small variants.
- Slow equilibration to multiple stable conformations in solution causes single-molecule heterogeneity.
- LDH-1 crystal activity variations highlight the impact of conformational selection during crystallization.
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