Single Motor Proteins and Semiflexible Polymer Networks

Christoph Schmidt

Copenhagen Summer School, August 2002

1. Lecture: Motor Proteins in Single-Molecule Experiments

Motor proteins are ubiquitous enzymes specialized in generating force and motion for a
multitude of dynamic processes in living organisms. This lecture will first introduce
techniques used in single-molecule in vitro motility assays focusing mainly on optical
tweezers as well as single-molecule fluorescence experiments. These techniques are
widely used for studying cytoskeletal motor proteins of the myosin and kinesin families.
Then I will present fundamental experimental results on selected systems and will
introduce and discuss concepts such as mechano-chemical coupling, power strokes and
steps, processivity and cooperativity. In the end I will point out where the current
challenges lie, also with an eye on the experimental limitations and possible future
developments.

2. Lecture: The Dynamics of Semiflexible Polymer Networks

Construction materials used by cells are commonly optimized by evolution for their tasks
and can often fulfill a multitude of different tasks in complex arrangements and
interactions within cells. In this lecture I will focus on the "semiflexible" polymer
systems forming the cytoskeleton of cells, which has both passive and active structural
tasks. Semiflexible polymers are somewhat exotic systems in polymer science, and I will
explain some of their characteristic properties. I will then concentrate on what dynamic
properties of such polymers can be measured in microscopic experiments, spanning the
range from single strands to entangled networks, introducing a group of techniques
labeled microrheology.