| Strong binding of myosin heads stretches and twists the actin helix. | |
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MedLine Citation:
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PMID: 15596509 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Calculation of the size of the power stroke of the myosin motor in contracting muscle requires knowledge of the compliance of the myofilaments. Current estimates of actin compliance vary significantly introducing uncertainty in the mechanical parameters of the motor. Using x-ray diffraction on small bundles of permeabilized fibers from rabbit muscle we show that strong binding of myosin heads changes directly the actin helix. The spacing of the 2.73-nm meridional x-ray reflection increased by 0.22% when relaxed fibers were put into low-tension rigor (<10 kN/m(2)) demonstrating that strongly bound myosin heads elongate the actin filaments even in the absence of external tension. The pitch of the 5.9-nm actin layer line increased by approximately 0.62% and that of the 5.1-nm layer line decreased by approximately 0.26%, suggesting that the elongation is accompanied by a decrease in its helical angle (approximately 166 degrees) by approximately 0.8 degrees. This effect explains the difference between actin compliance revealed from mechanical experiments with single fibers and from x-ray diffraction on whole muscles. Our measurement of actin compliance obtained by applying tension to fibers in rigor is consistent with the results of mechanical measurements. |
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Authors:
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Andrey K Tsaturyan; Natalia Koubassova; Michael A Ferenczi; Theyencheri Narayanan; Manfred Roessle; Sergey Y Bershitsky |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2004-12-13 |
Journal Detail:
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Title: Biophysical journal Volume: 88 ISSN: 0006-3495 ISO Abbreviation: Biophys. J. Publication Date: 2005 Mar |
Date Detail:
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Created Date: 2005-03-01 Completed Date: 2005-07-06 Revised Date: 2009-11-19 |
Medline Journal Info:
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Nlm Unique ID: 0370626 Medline TA: Biophys J Country: United States |
Other Details:
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Languages: eng Pagination: 1902-10 Citation Subset: IM |
Affiliation:
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Institute of Mechanics, M. V. Lomonosov Moscow State University, Moscow, Russia. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Actins
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analysis,
chemistry* Animals Binding Sites Cells, Cultured Elasticity Micromanipulation / methods* Molecular Motor Proteins / chemistry* Muscle Fibers, Skeletal / chemistry* Myosins / analysis, chemistry* Physical Stimulation / methods* Protein Binding Protein Conformation Psoas Muscles / chemistry Rats Rotation Sarcomeres / chemistry* Stress, Mechanical |
| Chemical | |
Reg. No./Substance:
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0/Actins; 0/Molecular Motor Proteins; EC 3.6.4.1/Myosins |
| Comments/Corrections | |
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