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Protein Crystallization for X-ray Crystallography
Published on: January 16, 2011
Hematin crystallization from aqueous and organic solvents.
Megan A Ketchum1, Katy N Olafson, Elena V Petrova
1Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, USA.
The Journal of Chemical Physics
|October 5, 2013
Summary
Malaria parasites detoxify heme via hematin crystallization. This study shows crystals grown in octanol, mimicking lipid bodies, resemble parasite crystals, unlike those in aqueous solutions. Lipid bodies likely accelerate heme detoxification.
Area of Science:
- Biochemistry
- Parasitology
- Malaria Research
Background:
- Heme detoxification in malaria is crucial, occurring via hematin crystallization within infected erythrocytes.
- A debate exists regarding whether hematin crystallization occurs in the aqueous digestive vacuole or lipid bodies.
Purpose of the Study:
- To investigate the role of lipid bodies in hematin crystallization and heme detoxification.
- To compare hematin crystallization in aqueous versus lipid-mimicking environments.
Main Methods:
- Comparative analysis of hematin crystallization in aqueous buffer (pH 4.8) and water-saturated octanol.
- Solubility determination of beta-hematin crystals across a pH range and in octanol.
- Atomic force microscopy (AFM) to characterize crystal morphology.
Main Results:
- Hematin aggregation was insignificant in aqueous solutions.
- Crystals grown in octanol closely resembled biological hemozoin, unlike those grown in aqueous buffer.
- Hematin solubility in octanol was significantly higher (four orders of magnitude) than in aqueous solution at pH 4.8.
Conclusions:
- Lipid bodies, mimicked by octanol, appear to play a critical role in mediating biological hemozoin formation.
- The higher solubility and faster crystallization in lipid environments suggest an efficient mechanism for heme detoxification by the malaria parasite.
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