Biophysics Seminar - 09/22/2021 - 1:00pm-2:00pm - 1080 Physics Research Building

1:00-1:30 Using NMR Spin Relaxation to Quantitatively Analyze Biomolecules Undergoing Exchange with Large Interaction Partners
Greg Jameson, Brüschweiler lab

Biomolecular solution NMR experiments, such as spin relaxation, relaxation dispersion, and related experiments, have consistently proven to be a rich source of quantitative dynamics and kinetics of biomolecules for elucidating their function at atomic detail. Traditional Redfield theory for analyzing these experiments requires several assumptions that may be violated in potentially valuable experiments. One system that violates these traditional assumptions is the transient interaction of biomolecules with large bodies, such as nanoparticles or static walls, especially when binding and unbinding occur on an intermediate timescale of around 104 s-1, which has been evidenced in practice. We have developed unified framework for analyzing such data based on the stochastic Liouville equation (SLE), which is valid regardless of binding partner size or kinetics of binding/unbinding. Application of this theory demonstrates how spin relaxation can be significantly impacted by the kinetics of binding. Furthermore, it is shown that when binding occurs on intermediate timescales, transverse spin relaxation is able to report on potentially relevant internal dynamics far slower than observable by traditional spin relaxation experiments.

1:30-2:00 Characterizing the force dependent properties of a DNA origami force probe
Ariel Robbins, Poirier lab

DNA origami nanotechnology is a rapidly developing field that shows promise in scientific applications such as mechanically aided drug delivery, molecular sensing, force sensing, and probing of single molecule dynamics. Complex and dynamic 3-dimensional structures can perform a prescribed function through controlled actuation making their use precise and reproducible. The device in our study, called a nanodyn, acts as a force sensor. Consisting of two origami bundles linked by six crossover strands, the device can exist in either an open or closed configuration. With careful design of the crossover strands, the nanodyn can be programed to open at a prescribed force. These nanoprobes can then be used in biological systems where traditional force spectroscopy techniques are more challenging to implement. For instance, shear forces due to fluid flow can be challenging to determine in non-idealized environments, such as in a blood vessel or extracellular matrix. This device will supplement the existing force spectroscopy toolkit available to scientists for probing biological systems.

Last update: 09/20/2021, Ralf Bundschuh