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Physics Colloquium - Dr Katharine Challis

Monday, 7 October 2019

Physics Department

Dr Katharine Challis


New Zealand

"Deriving discrete-continuous descriptions of motor proteins"

Motor proteins are specialised biomolecules that use chemical energy to carry out important tasks within the cell. The physiological mechanisms and performance of different motor proteins varies considerably. For example, F1ATPase is a highly-efficient rotary motor involved in ATP synthesis, whereas kinesin-1 is a cytoskeletal motor that transports cargo with very low efficiency.

Theoretical physics methods can be used to describe motor proteins and provide insights into aspects of their behaviour. This talk provides a short overview of current theoretical approaches and then will focus on two established methods: free-energy landscape theories and discretecontinuous models. Free-energy landscape theories (see Figure 1) provide a fundamental framework for describing biomolecules and have been successful for explaining protein folding. Discrete-continuous models (see Figure 2) are based on Brownian ratchet concepts and are often used for phenomenological modelling.

In this work, we begin with the free-energy landscape theory and systematically derive a discrete-continuous description consistent with phenomenological models. We give a physical interpretation of the discretecontinuous description and find good agreement with the landscape theory in the weak-coupling regime where the efficiency of energy conversion is low. High efficiency can be achieved for strong coupling, but the discretecontinuous description is no-longer valid in that case. This suggests that highly efficient motors are more appropriately described by a free-energy landscape theory.

We discuss the implications of these results for understanding motor proteins and for the design of artificial nanomotors that are expected to find applications in medicine, energy, and materials.


WHEN: Monday 7th October 2019
WHERE: Room 314, Science 3 Building
TIME: 3.00 pm–4.00 pm

All interested are welcome to attend

Light refreshments to follow in Common Room