Crystallization and crystal data of monellin
1Department of Chemistry, Stanford University, Stanford, California, 94305.
Summary
Researchers crystallized the sweet protein monellin from Dioscoreophyllum cumminsii. This breakthrough enables near-atomic resolution X-ray structural analysis of this natural sweetener.
Area of Science:
- Biochemistry
- Structural Biology
- Crystallography
Background:
- Monellin is a naturally occurring sweet protein found in the fruit of Dioscoreophyllum cumminsii.
- Understanding the three-dimensional structure of monellin is crucial for elucidating its sweet taste mechanism and for potential applications in food science.
- Previous structural studies may have been limited by crystal quality or resolution.
Purpose of the Study:
- To obtain high-quality crystals of monellin suitable for X-ray diffraction analysis.
- To determine the crystallographic parameters of this new crystal form.
- To assess the potential for near-atomic resolution structural determination.
Main Methods:
- Protein crystallization using the vapor diffusion method.
- Preparation of buffered protein solutions with 20% ethanol.
- X-ray diffraction analysis to determine crystal system, space group, and unit cell dimensions.
Main Results:
- Successfully grew orthorhombic crystals of monellin (space group P2(1)2(1)2).
- Determined unit cell parameters: a = 54.4 A, b = 113.0 A, c = 40.8 A, V = 250,300 A(3).
- The asymmetric unit contains two monellin molecules, and diffraction extends to at least 2.5 A resolution.
Conclusions:
- The obtained crystal form of monellin is suitable for high-resolution X-ray structural analysis.
- This facilitates detailed investigation into the molecular basis of sweetness.
- Opens avenues for structure-based design of novel sweetening agents.
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