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Titin (Visco-) Elasticity in Skeletal Muscle Myofibrils

JA. Herzog, TR. Leonard, A. Jinha, W. Herzog†,‡

* Mount Allison University, Department of Biology, Sackville, NB, Canada.
University of Calgary, Faculty of Kinesiology, Calgary, AB, Canada.
Corresponding Author. Faculty of Kinesiology, 2500 University Dr. NW, Calgary, AB, T2N 1N4. Phone: 403-220-8525; Email: walter@kin.ucalgary.ca

Molecular & Cellular Biomechanics 2014, 11(1), 1-17. https://doi.org/10.3970/mcb.2014.011.001

Abstract

Titin is the third most abundant protein in sarcomeres and fulfills a number of mechanical and signaling functions. Specifically, titin is responsible for most of the passive forces in sarcomeres and the passive visco-elastic behaviour of myofibrils and muscles. It has been suggested, based on mechanical testing of isolated titin molecules, that titin is an essentially elastic spring if Ig domain un/refolding is prevented either by working at short titin lengths, prior to any unfolding of Ig domains, or at long sarcomere (and titin) lengths when Ig domain un/refolding is effectively prevented. However, these properties of titin, and by extension of muscles, have not been tested with titin in its natural structural environment within a sarcomere. The purpose of this study was to gain insight into the Ig domain un/refolding kinetics and test the idea that titin could behave essentially elastically at any sarcomere length by preventing Ig domain un/refolding during passive stretch-shortening cycles. Although not completely successful, we demonstrate here that titin’s visco-elastic properties appear to depend on the Ig domain un/refolding kinetics and that indeed, titin (and thus myofibrils) can become virtually elastic when Ig domain un/refolding is prevented.

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Cite This Article

Herzog, J., Leonard, T., Jinha, A., Herzog, W. (2014). Titin (Visco-) Elasticity in Skeletal Muscle Myofibrils. Molecular & Cellular Biomechanics, 11(1), 1–17.



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