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Theory of Muscular Contraction Extended to Groups of Actin Sites
Terrell L. Hill
Proceedings of the National Academy of Sciences of the United States of America
Vol. 70, No. 10 (Oct., 1973), pp. 2732-2736
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/63092
Page Count: 5
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It was shown in an earlier paper how to connect, in principle, the biochemical states of a cross-bridge with the mechanics of muscular contraction, by the methods of statistical mechanics. The treatment applies to cross-bridges that are able to interact with only one actin site at a time. The present paper shows that it is a straightforward matter to extend the theory to groups of actin sites (three, five, etc.), say 55 angstrom apart, as suggested by the work of Moore, H. E. Huxley, and DeRosier. The possibility of the cross-bridge attachment slipping between sites is included. This provides an alternative molecular interpretation of the model introduced by A. F. Huxley and Simmons. A second possible interpretation is also suggested: their discrete stable angles correspond to different biochemical (attached) states. The Huxley-Simmons analysis of an example is rederived and extended somewhat (x averaging), from the point of view of the present theory. Their qualitative conclusions are left unchanged by the x averaging, but significant quantitative effects are possible. Possible consequences of fast slipping in isotonic contraction are discussed in a preliminary way.
Proceedings of the National Academy of Sciences of the United States of America © 1973 National Academy of Sciences