Bonds, Catch Bonds, and Statistics

Unsurprisingly, education research shows that students engage better when an instructional storyline begins with a surprising claim about topic important in their own lives. Today, everyone understands the importance of immune response to lives, and most find it paradoxical be told some bonds strengthen under applied pulling force. So recent discovery catch-bond behavior T-cell activation is very good starting point motivate study many molecular biophysics ideas. To understand claim, we must discuss nature bonds, replace “strength” by statistical notion mean lifetime, then introduce random walks on energy landscapes. Rather than elaborate technical Kramers theory, however, can readily perform simple simulations. The results include memorable animated graphics, make themselves platform such as Python or MATLAB, yield conceptual insight into bond formation breakage, isomerization, so on. Abstractions Boltzmann distribution exponentially distributed lifetime emerge concrete consequences rules, origin catch bonding clear multiple unbinding routes are available. I will present module suitable for installation advanced undergrad-level general Biophysics course freely available line: see https://repository.upenn.edu/physics_papers/660/.