Biomathematics Seminar
Tuesday 1/22/08

Speaker: Martin Bier, Department of Physics, East Carolina University

Title: Motor proteins, dolphins, and Winnetou - or - How irregular motion can sometimes be the fastests and most efficient

Abstract:
The motor protein kinesin literally walks on two legs along the
biopolymer microtubule as it hydrolyzes ATP for its fuel supply.  The
number of accidental backsteps that kinesin takes appears to be much
larger than what one would expect given the amount of free energy
that ATP hydrolysis makes available.  This is puzzling as more than a
billion years of natural selection should have optimized the motor
protein for its speed and efficiency. 

I will point out how the stepping kinesin is a realization of
Bennett’s well-known information-driven heat engine operating in
reverse and I will analyze the production and destruction of Shannon
entropy.  More backstepping allows for the production of more
entropy.  The production of entropy will make free energy available. 
With that free energy, the catalytic cycle of the kinesin can be
speeded up.  I will show how the actually measured backstepping rate
represents an optimum at which maximal net forward speed is
achieved.