Related Experiment Video
Updated: Aug 6, 2026
13:51
Demonstrating the Uses of the Novel Gravitational Force Spectrometer to Stretch and Measure Fibrous Proteins
Published on: March 19, 2011
Can non-mechanical proteins withstand force? Stretching barnase by atomic force microscopy and molecular dynamics
1Department of Chemistry, University of Cambridge, MRC Centre for Protein Engineering, Cambridge CB2 1EW, United Kingdom.
Biophysical Journal
|September 22, 2001
Summary
Proteins not evolved for mechanical resistance, like barnase, unfold differently under force than force-bearing proteins, such as titin I27. Atomic force microscopy reveals distinct unfolding pathways and lower force requirements for barnase.
Area of Science:
- Biophysics
- Protein Mechanics
- Molecular Biology
Background:
- Atomic force microscopy (AFM) has elucidated protein mechanical unfolding, primarily in force-resistant proteins like titin I27.
- The mechanical unfolding behavior of proteins not adapted for force resistance remains less understood.
Purpose of the Study:
- To investigate the forced unfolding of barnase, a protein not physiologically required to resist force, using AFM.
- To compare the mechanical unfolding properties of barnase with those of force-bearing proteins.
Main Methods:
- Atomic force microscopy (AFM) experiments were conducted on a chimeric construct containing barnase and titin I27.
- Molecular dynamics (MD) simulations were employed to model barnase unfolding.
- Analysis of force-distance curves to identify unfolding events and transition states.
Main Results:
- Barnase exhibited distinct, low-force unfolding peaks in AFM experiments, differing from titin I27.
- MD simulations indicated that barnase unfolds at lower forces compared to mechanically functional proteins.
- Barnase unfolding involved terminal unraveling, retaining more native-like structure in the transition state than observed in thermal or chemical denaturation.
Conclusions:
- Proteins not selected for tensile strength may possess unique mechanical unfolding mechanisms.
- Unfolding rates in solution do not necessarily predict mechanical unfolding behavior under force.
- AFM and MD simulations provide insights into the distinct mechanical properties of non-force-bearing proteins.
Related Concept Videos
01:58Mechanical Protein Functions
Proteins perform many mechanical functions in a cell. These proteins can be classified into two general categories- proteins that generate mechanical forces and proteins that are subjected to mechanical forces. Proteins providing mechanical support to the structure of the cell, such as keratin, are subjected to mechanical force, whereas proteins involved in cell movement and transport of molecules across cell membranes, such as an ion pump, are examples of generating mechanical force.
01:17Studying the Cytoskeleton
The cytoskeletal architecture can be studied using different microscopic and biochemical techniques. Electron microscopy was instrumental in discovering the cytoskeletal architecture around the 1960s, which allowed obtaining structural information at a high-resolution level. However, the sample preparation procedure often limits this ability in biological samples. Several protocols have been developed over the years to optimize sample preparation. In one of the protocols known as rotary...