Rotation of the lever arm of Myosin in contracting skeletal muscle fiber measured by two-photon anisotropy

Biophysical Journal
J BorejdoJ Malicka

Abstract

The rotation of the lever arm of myosin cross-bridges is believed to be responsible for muscle contraction. To resolve details of this rotation, it is necessary to observe a single cross-bridge. It is still impossible to do so in muscle fiber, but it is possible to investigate a small population of cross-bridges by simultaneously activating myosin in a femtoliter volume by rapid release of caged ATP. In earlier work, in which the number of observed cross-bridges was limited to approximately 600 by confocal microscopy, we were able to measure the rates of cross-bridge detachment and rebinding. However, we were unable to resolve the power stroke. We speculated that the reason for this was that the number of observed cross-bridges was too large. In an attempt to decrease this number, we used two-photon microscopy which permitted observation of approximately 1/2 as many cross-bridges as before with the same signal/noise ratio. With the two-photon excitation, the number of cross-bridges was small enough to resolve the beginning of the power stroke. The results indicated that the power stroke begins approximately 170 ms after the rigor cross-bridge first binds ATP.

References

Feb 1, 1966·Biochemistry·Y TonomuraM Morales
Dec 16, 1997·Biophysical Chemistry·H MalakJ R Lakowicz
Jul 8, 1998·Proceedings of the National Academy of Sciences of the United States of America·D M WarshawC Berger
Apr 2, 2003·Biophysical Journal·J Borejdo, I Akopova
Mar 26, 2004·Biophysical Journal·J BorejdoT P Burghardt

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Citations

Mar 9, 2007·Journal of Biomedical Optics·Julian BorejdoThomas P Burghardt
Jul 18, 2006·Biophysical Journal·J BorejdoI Gryczynski
Mar 3, 2006·Biochimica Et Biophysica Acta·J BorejdoT P Burghardt
Jan 14, 2005·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·Hugh E Huxley
Jun 6, 2006·American Journal of Physiology. Heart and Circulatory Physiology·D DumkaJ Borejdo
Dec 29, 2005·Experimental Biology and Medicine·Julian BorejdoIrina Akopova
Dec 1, 2012·Biophysics Reviews·J BorejdoK Midde

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