Cross-Linking Studies Related to the Location of the Rigor Compliance in Glycerinated Rabbit Psoas Fibers: Is the SII Portion of the Cross-Bridge Compliant?
Part of the
Advances in Experimental Medicine and Biology
book series (AEMB, volume 37)
The muscle tension generation model of Huxley and Simmons (1971) postulates an independent elastic element in the cross-bridge. This elastic structure was tentatively placed in the SII portion of the cross-bridge in the model. To check this assumption, we fixed the SII portion onto the surface of the thick filament in glycerinated rabbit psoas fibers in rigor by chemically cross-linking with dimethyl suberimidate, and compared the stiffness of the cross-linked fibers with that of the fibers before cross-linking. The stiffness was determined by measuring the tension increment upon stretching a fiber segment in rigor. The contribution of the end compliance was found to be small.
Cross-linking increased the rigor stiffness by 20 to 30%. Almost the same amount of the stiffness increase was also observed at a sarcomere length where there was no overlap between the thin and thick filaments, and in a fiber segment cross-linked in relaxing solution. Therefore, the 20 to 30% increase of the stiffness is not caused by the fixation of the SII portion onto the thick filament but caused by the cross-linking of some parallel elastic components. Since the rigor stiffness before cross-linking is almost proportional to the overlap between thick and thin filaments, we conclude that the muscle stiffness in rigor does not originate in the SII portion but reflects some compliance of the head portion of the cross-bridge.
KeywordsThin Filament Sarcomere Length Thick Filament Relaxing Solution Fiber Segment
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Chiao, Y.-C.C. and Harrington, W.F. (1979). Cross-bridge movement in glycerinated rabbit psoas muscle fiber. Biochemistry 18: 959–963.PubMedCrossRefGoogle Scholar
Civan, M.M. and Podolsky, R.J. (1964). Contraction kinetics of striated muscle fibers following quick changes in load. J. Physiol. 184: 511–534.Google Scholar
Cooke, R. (1981). Stress does not alter the conformation of a domain of the myosin cross-bridge in rigor muscle fibers. Nature 249: 570–571.CrossRefGoogle Scholar
Eastwood, A.B., Wood, D.S., Bock, K.L. and Sorenson, M.M. (1979). Chemically skinned mammalian skeletal muscle. 1. The structure of skinned rabbit psoas. Tissue. Cell. 11: 553–556.PubMedCrossRefGoogle Scholar
Eisenberg, E. and Hill, T.L. (1978). A cross-bridge model of muscle contraction. Prog. Biophys. Mol. Biol. 33: 55–80.PubMedCrossRefGoogle Scholar
Elliott, A. and Offer, G. (1978). Shape and flexibility of myosin molecule. J. Mol. Biol. 123: 505–519.PubMedCrossRefGoogle Scholar
Güth, K. and Kuhn, H.J. (1978). Stiffness and tension during and after sudden length changes of glycerinated rabbit psoas fibers. Biophys. Struct. Mech. 4: 223–236.PubMedCrossRefGoogle Scholar
Huxley, A.F. and Simmons, R.M. (1971). Proposed mechanism of force generation in striated muscle. Nature 233: 533–538.PubMedCrossRefGoogle Scholar
Huxley, A.F. (1974). Review lecture muscular contraction. J. Physiol. 243: 1–43.PubMedGoogle Scholar
Naylor, G.R.S. and Podo’sky, R.J. (1981). X-ray diffraction of strained muscle fibers in rigor. Proc. Natl. Acad. Sci. U.S.A. 78: 5559–5563.PubMedCrossRefGoogle Scholar
Sutoh, K. and Harrington, W.F. (1977). Cross-linking of myosin thick filaments under activating and rigor conditions. A study of the radial disposition of cross-bridges. Biochemistry 16: 2441–2449.PubMedCrossRefGoogle Scholar
Ueno, H. and Harrington, W.F. (1981). Cross-bridge movement and the myosin hinge in skeletal muscle. J. Mol. Biol. 149: 619–640.PubMedCrossRefGoogle Scholar
© Plenum Press, New York 1984