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. "