Colloquium, April 23th, 2015 -- The Physics of Titin and Muscle Function

Julio Fernandez Columbia University The Physics of Titin and Muscle Function Current theories of muscle contraction largely exclude titin, the largest protein in the human body, which determines the passive elasticity of muscles. I will show how to construct the free energy of a titin-like model protein, and how we can use this free energy to predict the behavior of titin in intact tissues. I will demonstrate the use of single molecule force-spectroscopy techniques to probe the folding of titin domains and measure the contribution that they make to the force generated by a contracting muscle. I will show that the folding of single titin domains can generate in excess of 100zJ of contractile energy, which is larger than the mechanical energy delivered by the power stroke of a myosin motor. Hence, the folding of titin Ig domains is an important contributor to the force generated by a contracting muscle.