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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
3
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pubmed:dateCreated |
2001-3-6
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pubmed:abstractText |
The elastic section of the giant muscle protein titin contains many immunoglobulin-like domains, which have been shown by single-molecule mechanical studies to unfold and refold upon stretch-release. Here we asked whether the mechanical properties of Ig domains and/or other titin regions could be responsible for the viscoelasticity of nonactivated skeletal-muscle sarcomeres, particularly for stress relaxation and force hysteresis. We show that isolated psoas myofibrils respond to a stretch-hold protocol with a characteristic force decay that becomes more pronounced following stretch to above 2.6-microm sarcomere length. The force decay was readily reproducible by a Monte Carlo simulation taking into account both the kinetics of Ig-domain unfolding and the worm-like-chain model of entropic elasticity used to describe titin's elastic behavior. The modeling indicated that the force decay is explainable by the unfolding of only a very small number of Ig domains per titin molecule. The simulation also predicted that a unique sequence in titin, the PEVK domain, may undergo minor structural changes during sarcomere extension. Myofibrils subjected to 1-Hz cycles of stretch-release exhibited distinct hysteresis that persisted during repetitive measurements. Quick stretch-release protocols, in which variable pauses were introduced after the release, revealed a two-exponential time course of hysteresis recovery. The rate constants of recovery compared well with the refolding rates of Ig-like or fibronectin-like domains measured by single-protein mechanical analysis. These findings suggest that in the sarcomere, titin's Ig-domain regions may act as entropic springs capable of adjusting their contour length in response to a stretch.
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pubmed:grant |
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/11222304-10047523,
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Mar
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pubmed:issn |
0006-3495
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
80
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
1442-51
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pubmed:dateRevised |
2009-11-19
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pubmed:meshHeading |
pubmed-meshheading:11222304-Amino Acid Sequence,
pubmed-meshheading:11222304-Animals,
pubmed-meshheading:11222304-Elasticity,
pubmed-meshheading:11222304-Kinetics,
pubmed-meshheading:11222304-Models, Biological,
pubmed-meshheading:11222304-Monte Carlo Method,
pubmed-meshheading:11222304-Muscle, Skeletal,
pubmed-meshheading:11222304-Muscle Contraction,
pubmed-meshheading:11222304-Muscle Proteins,
pubmed-meshheading:11222304-Myofibrils,
pubmed-meshheading:11222304-Protein Folding,
pubmed-meshheading:11222304-Protein Kinases,
pubmed-meshheading:11222304-Rats,
pubmed-meshheading:11222304-Stress, Mechanical,
pubmed-meshheading:11222304-Time Factors,
pubmed-meshheading:11222304-Viscosity
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pubmed:year |
2001
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pubmed:articleTitle |
Unfolding of titin domains explains the viscoelastic behavior of skeletal myofibrils.
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pubmed:affiliation |
Institute of Physiology and Pathophysiology, University of Heidelberg, D-69120 Heidelberg, Germany.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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