J. Biochem, 2003, Vol. 133, No. 2 207-210
© 2003 Japanese Biochemical Society
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An X-Ray Diffraction Study on the ADP-Induced Conformational Change in Skeletal Muscle Myosin
1 Department of Physiology, Oita Medical University, Hasama, Oita 879-55; 2 Japan Synchrotron Radiation Research Institute, SPring-8, Kouto, Mikazuki, Sayo, Hyogo 679-5198; and 3 Department of Physiology, The Jikei University School of Medicine, Minato-ku, Tokyo 105-8461
Effects of ADP on the conformation of myosin cross-bridges were studied in x-ray diffraction experiments on single skinned fibers of frog skeletal muscle by photorelease of ADP from caged-ADP. The experiments were performed at the third-generation synchrotron radiation facility SPring-8 with a time resolution of 5 ms. The intensity of the third-order meridional reflection from myosin filaments (at 1/14.4 nm1) increased promptly after the ADP release with a time constant smaller than 5 ms, which was similar to that of tension decline. The results show that ADP binding induces a conformational change of myosin in skeletal muscle fibers.
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