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Submillisecond changes in myosin lattice spacing resulting from rapid length changes11Edited by M. F. Moody
- Source :
- JMB Online (Journal of Molecular Biology); January 1999, Vol. 285 Issue: 1 p431-440, 10p
- Publication Year :
- 1999
-
Abstract
- The speed of the myofilament lattice spacing response to rapid changes in load or length of single, intact muscle fibres of the frog, was investigated during isometric tetani. During ramp releases at close to Vmaxand during step length changes (completed within 250 μs), lattice spacing was calculated from the equatorial X-ray diffraction pattern (sampled at 250 μs time resolution using synchrotron radiation). Ramp releases (total shortening = 1.39 %) caused a spacing increase, described with an exponential function (α = 271 s−1, amplitude = 1.15 nm) plus an elastic component having the time course of discharge of axial tension (amplitude 0.28 nm). For a step release (amplitude = 0.87 %), lattice expansion could be described with an exponential (α = 1005 s−1, amplitude = 0.56 nm) plus an elastic component of 0.25 nm amplitude. Lattice compression was associated with a step stretch (amplitude = 0.62 %), and was also quasi-exponential (α = 367 s−1, amplitude = 0.74 nm), with an elastic component of 0.28 nm. The spacing change time course for length steps resembled that of the accompanying quick recovery of axial tension and the associated change in the meridional 14.5 nm reflection intensity, which are both believed to be determined by the kinetics of the molecular power stroke. Therefore, this shows that lattice spacing changes, arising from radial forces exerted by attached crossbridges, are fast enough to occur during the power stroke event.
Details
- Language :
- English
- ISSN :
- 00222836 and 10898638
- Volume :
- 285
- Issue :
- 1
- Database :
- Supplemental Index
- Journal :
- JMB Online (Journal of Molecular Biology)
- Publication Type :
- Periodical
- Accession number :
- ejs3918641
- Full Text :
- https://doi.org/10.1006/jmbi.1998.2331