Wendy Thomas, Ph.D.
Department of Bioengineering
"Molecular Biomechanics: Proteins & Mechanical Force" 

"The mechanical properties of individual proteins are fundamentally different from the macroscopic mechanical properties of most materials.  For example, instead of stretching uniformly according to the elastic modulus, a protein's response to force is quantized, probabilistic, and depends on the molecular structure.  This is because proteins, which are long polymers of various amino acids, fold up into distinct low energy conformations, rather than taking on a continuum of shapes.  Mechanical force pushes the protein to jump into a new low-energy conformation, which often has a different biological function than does the native one.  I study a bacterial adhesive protein in which the new force-induced low-energy conformation binds more strongly to its target.  Because of this, the adhesive protein forms "catch-bonds" that last longer under tensile mechanical force, and the bacteria using this adhesive protein bind best when you try to wash them off. "