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Direct observation of enzyme activity with the atomic force microscope
M Radmacher1, M Fritz, H G Hansma
1Department of Physics, University of California, Santa Barbara 93106.
Science (New York, N.Y.)
|September 9, 1994
Summary
Protein lysozyme undergoes height fluctuations during hydrolysis, observed via atomic force microscopy. These changes are linked to substrate interaction and may indicate conformational shifts in the enzyme.
Area of Science:
- Biophysics
- Enzymology
Background:
- Lysozyme is a key enzyme in biological systems.
- Understanding enzyme dynamics is crucial for drug development.
Purpose of the Study:
- To investigate the dynamic behavior of lysozyme.
- To correlate observed fluctuations with enzymatic activity.
Main Methods:
- Atomic Force Microscopy (AFM) in tapping mode.
- Measurements performed on lysozyme adsorbed on mica in liquid.
Main Results:
- Observed 1 nm height fluctuations of ~50 ms duration over lysozyme molecules.
- Fluctuations decreased significantly in the presence of chitobiose (inhibitor).
- Substrate (oligoglycoside) presence induced these fluctuations.
Conclusions:
- Height fluctuations likely represent lysozyme conformational changes during hydrolysis.
- Alternative explanation involves transient complex height/elasticity variations.
- AFM provides insights into enzyme-substrate interactions and dynamics.