Correction: X-ray Diffraction of Strained Muscle Fibers in Rigor

1981 ◽  
Vol 78 (12) ◽  
pp. 7844-7844
Keyword(s):  
Muscle Fibers ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Backward Movements of Cross-Bridges by Application of Stretch and by Binding of MgADP to Skeletal Muscle Fibers in the Rigor State as Studied by X-Ray Diffraction

1999 ◽  
Vol 76 (4) ◽  
pp. 1770-1783 ◽  
Author(s):  
Yasunori Takezawa ◽  
Duck-Sool Kim ◽  
Masaki Ogino ◽  
Yasunobu Sugimoto ◽  
Takakazu Kobayashi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rigor State ◽  
Skeletal Muscle Fibers ◽  
Cross Bridges

scholarly journals X-ray Diffraction Studies on the Structural Origin of Dynamic Tension Recovery Following Ramp-Shaped Releases in High-Ca Rigor Muscle Fibers

2020 ◽  
Vol 21 (4) ◽  
pp. 1244
Author(s):  
Haruo Sugi ◽  
Maki Yamaguchi ◽  
Tetsuo Ohno ◽  
Hiroshi Okuyama ◽  
Naoto Yagi
Keyword(s):  
Muscle Contraction ◽  
Actin Filaments ◽  
Myosin Head ◽  
Muscle Fibers ◽  
Skinned Fibers ◽  
Myosin Filament ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tension Recovery ◽  
Pass Through

It is generally believed that during muscle contraction, myosin heads (M) extending from myosin filament attaches to actin filaments (A) to perform power stroke, associated with the reaction, A-M-ADP-Pi → A-M + ADP + Pi, so that myosin heads pass through the state of A-M, i.e., rigor A-M complex. We have, however, recently found that: (1) an antibody to myosin head, completely covering actin-binding sites in myosin head, has no effect on Ca2+-activated tension in skinned muscle fibers; (2) skinned fibers exhibit distinct tension recovery following ramp-shaped releases (amplitude, 0.5% of Lo; complete in 5 ms); and (3) EDTA, chelating Mg ions, eliminate the tension recovery in low-Ca rigor fibers but not in high-Ca rigor fibers. These results suggest that A-M-ADP myosin heads in high-Ca rigor fibers have dynamic properties to produce the tension recovery following ramp-shaped releases, and that myosin heads do not pass through rigor A-M complex configuration during muscle contraction. To obtain information about the structural changes in A-M-ADP myosin heads during the tension recovery, we performed X-ray diffraction studies on high-Ca rigor skinned fibers subjected to ramp-shaped releases. X-ray diffraction patterns of the fibers were recorded before and after application of ramp-shaped releases. The results obtained indicate that during the initial drop in rigor tension coincident with the applied release, rigor myosin heads take up applied displacement by tilting from oblique to perpendicular configuration to myofilaments, and after the release myosin heads appear to rotate around the helical structure of actin filaments to produce the tension recovery.

scholarly journals X-ray diffraction analysis of the effects of myosin regulatory light chain phosphorylation and butanedione monoxime on skinned skeletal muscle fibers

2016 ◽  
Vol 310 (8) ◽  
pp. C692-C700 ◽  
Author(s):  
Maki Yamaguchi ◽  
Masako Kimura ◽  
Zhao-bo Li ◽  
Tetsuo Ohno ◽  
Shigeru Takemori ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Muscle Fibers ◽  
Structural Basis ◽  
Myosin Regulatory Light Chain ◽  
X Ray Diffraction ◽  
Phosphate Release ◽  
X Ray ◽  
Thick Filaments ◽  
Butanedione Monoxime

The phosphorylation of the myosin regulatory light chain (RLC) is an important modulator of skeletal muscle performance and plays a key role in posttetanic potentiation and staircase potentiation of twitch contractions. The structural basis for these phenomena within the filament lattice has not been thoroughly investigated. Using a synchrotron radiation source at SPring8, we obtained X-ray diffraction patterns from skinned rabbit psoas muscle fibers before and after phosphorylation of myosin RLC in the presence of myosin light chain kinase, calmodulin, and calcium at a concentration below the threshold for tension development ([Ca2+] = 10−6.8 M). After phosphorylation, the first myosin layer line slightly decreased in intensity at ∼0.05 nm−1 along the equatorial axis, indicating a partial loss of the helical order of myosin heads along the thick filament. Concomitantly, the (1,1/1,0) intensity ratio of the equatorial reflections increased. These results provide a firm structural basis for the hypothesis that phosphorylation of myosin RLC caused the myosin heads to move away from the thick filaments towards the thin filaments, thereby enhancing the probability of interaction with actin. In contrast, 2,3-butanedione monoxime (BDM), known to inhibit contraction by impeding phosphate release from myosin, had exactly the opposite effects on meridional and equatorial reflections to those of phosphorylation. We hypothesize that these antagonistic effects are due to the acceleration of phosphate release from myosin by phosphorylation and its inhibition by BDM, the consequent shifts in crossbridge equilibria leading to opposite changes in abundance of the myosin-ADP-inorganic phosphate complex state associated with helical order of thick filaments.

scholarly journals X-ray diffraction of strained muscle fibers in rigor.

1981 ◽  
Vol 78 (9) ◽  
pp. 5559-5563 ◽  
Author(s):  
G. R. Naylor ◽  
R. J. Podolsky
Keyword(s):  
Muscle Fibers ◽  
X Ray Diffraction ◽  
X Ray
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