title: Titin (visco-) elasticity in skeletal muscle myofibrils.
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 un- folding 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 do- main un/refolding kinetics and that indeed, titin (and thus myofibrils) can become virtually elastic when Ig domain un/refolding is prevented.
authors.forename: J A
authors.initials: JA
authors.lastname: Herzog
authors.forename: T R
authors.initials: TR
authors.lastname: Leonard
authors.forename: A
authors.initials: A
authors.lastname: Jinha
authors.forename: W
authors.initials: W
authors.lastname: Herzog
mesh_terms: D000818:Animals; D064211:Connectin; D004548:Elasticity; D007700:Kinetics; D009119:Muscle Contraction / Q000502:physiology; D058849:Protein Refolding; D017434:Protein Structure, Tertiary; D058767:Protein Unfolding; D011817:Rabbits; D012518:Sarcomeres / Q000737:chemistry* / Q000378:metabolism
chemical_list: D064211:Connectin