I am primarily excited by the inroads physical thinking is making into cell and molecular biology. The mechanics and dynamics of cellular processes are an area that physics, biology and chemistry can come together to study aspects of transport, motility, division, signaling - any process which happens in time. A phenomenal animation of these types of dynamic processes is the Inner Life of the Cell, which illustrates how non-static a cell is.
Two areas my students and I have focused on are the mechanics of microtubules and the kinetics of kinesin transport.
Microtubules are polymers of tubulin proteins, and are a major component of animal cell’s skeleton, the cytoskeleton. As such, they contribute to the mechanical stability of the cell as a whole, and underlie transport processes in endocytosis, cell division, and neurons. My group uses microtubule gliding (see video below) to measure the stiffness of these polymers.
Kinesin is a motor enzyme which transports cargos along microtubules, over short distances in most animal cells and incredibly long distances (a meter) in motor neurons. The process by which these single molecules convert chemical energy in the form of ATP into mechanical work remains an active area of study. Our group has been working on the kinetics of this process by tracking individual moving kinesins (see video right).
The unifying experimental theme for this research is a single molecule fluorescence approach, using a total internal reflection fluorescence (TIRF) microscope (picture at top). This microscope was constructed at Lawrence by LU students, and is capable of imaging single molecules to ~1-2 nm precision. This has enabled us to study both the kinetics of kinesin moving in 8 nm steps along microtubules and the microtubules themselves.