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Plastic deformation of protein monolayers
Mukta Singh-Zocchi1, Jeungphill Hanne, Giovanni Zocchi
1Department of Physics and Astronomy, University of California, Los Angeles, 90095, USA. zocchi@physics.ucla.edu
Biophysical Journal
|September 27, 2002
Summary
Globular proteins, like albumin and myoglobin, can be plastically deformed without melting. This research shows proteins can undergo irreversible shape changes while maintaining their solid state.
Area of Science:
- Biophysics
- Materials Science
- Protein Science
Background:
- Globular proteins exhibit both conformational stability and the capacity for large shape changes.
- It remains unclear if proteins can undergo plastic deformation, akin to solids, without denaturation.
Purpose of the Study:
- To investigate the plastic deformability of globular proteins under mechanical stress.
- To determine if proteins maintain their solid state after significant deformation.
Main Methods:
- Micro-mechanical experiments were conducted on protein monolayers (albumin and myoglobin) adsorbed onto a rigid surface.
- Small stresses were applied over extended periods to induce and observe molecular deformation.
Main Results:
- Proteins (albumin and myoglobin) showed substantial, irreversible deformation (1-2 nm) under applied stress.
- Deformed proteins retained their solid-state properties, indicated by a non-zero shear modulus.
- The deformation dynamics followed a logarithmic time dependence, similar to creep in conventional solids.
Conclusions:
- Globular proteins adsorbed on surfaces can be plastically deformed.
- Proteins can undergo significant, irreversible shape changes while maintaining solid-state characteristics.