Related Experiment Videos
The optical activity of lysozyme crystals
J Kobayashi1, T Asahi, M Sakurai
1Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, Tokyo, Japan.
Summary
Lysozyme
Area of Science:
- Biophysics
- Structural Biology
- Enzymology
Background:
- Lysozyme exhibits unusual optical activity despite its high alpha-helix content.
- Understanding lysozyme's optical properties is crucial for elucidating its structure-function relationship.
Purpose of the Study:
- To measure the gyration tensor components of lysozyme.
- To calculate optical rotatory powers and analyze the anisotropy.
- To investigate structural differences between crystalline and solution states of lysozyme.
Main Methods:
- Hydrodynamic and Optical Properties Measurement (HAUP) method was employed.
- Gyration tensor components (g11, g33) were determined at 303.4 K and 4880 A.
- Optical rotatory powers (rho a, rho c) were calculated.
Main Results:
- Gyration tensor components and optical rotatory powers were quantified.
- Lysozyme showed unexpectedly small optical rotatory powers with large anisotropy.
- A chirality index (r = 0.16) indicated a 19% increase in optical activity upon crystallization.
Conclusions:
- Lysozyme's optical properties are anomalous compared to typical chiral molecules.
- The chirality index suggests increased structural constraint in crystalline lysozyme.
- Structural changes significantly impact lysozyme's optical activity.