Mills Research Group

Single molecule enzyme activity, dynamics, and kinetics

Welcome to the Mills Research Group website!

Our research focuses on the activity and conformational dynamics of DNA-processing enzymes at the single molecule level. We use a combination of magnetic tweezers force experiments, single molecule fluorescence, and computer simulations to understand the behaviors of helicases and topoisomerases, enzymes that manipulate the structure of DNA.

Magnetic Tweezers Measurements

The Mills Lab uses magnetic tweezers and combined magnetic tweezers-fluorescence microscopy to detect changes in biomolecular structures. In a magnetic tweezers setup, a pair of permanent magnets is used to apply force to or rotate a paramagnetic bead attached to the system of interest. The z position of the bead is measured using widefield microscopy and changes in the height of the bead are recorded in real time. Magnetic tweezers can be combined with fluorescence microscopy to add a second coordinate for measurements.

The Mills Lab currently has two Magnetic Tweezers instruments, a home-built MT microscope and a custom MT-fluorescence Microscope from MadCity Labs with three-color fluorescence capabilities.

Molecular Dynamics Simulations

To complement our single molecule experiments, we use computational approaches to predict the structural changes in proteins that produce our experimental measurements. MD simulations provide atomistic details of the motions of biological molecules. We use these simulations to calculate the free energy profiles underlying these motions.