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Updated: Jul 10, 2026

X-ray Diffraction of Intact Murine Skeletal Muscle as a Tool for Studying the Structural Basis of Muscle Disease
Published on: July 18, 2019
Intensification of the 5.9-nm actin layer line in contracting muscle
Abstract:
According to the cross-bridge model of muscle contraction, an interaction of myosin heads with interdigitating actin filaments produces tension. Although X-ray equatorial diffraction patterns of active (contracting) muscle show that the heads are in the vicinity of the actin filaments, structural proof of actual attachment of heads to actin during contraction has been elusive. We show here that during contraction of frog skeletal muscle, the 5.9-nm layer line arising from the genetic helix of actin is intensified by as much as 56% of the change which occurs when muscle enters rigor, using a two-dimensional X-ray detector. This provides strong structural evidence that myosin heads do in fact attach during contraction.
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