Mechanical and structural properties underlying contraction of skeletal muscle fibers after partial 1-ethyl-3-[3-dimethylamino)propyl]carbodiimide cross-linking

Biophys J. 1996 Sep;71(3):1462-74. doi: 10.1016/S0006-3495(96)79347-5.


We show prolonged contraction of permeabilized muscle fibers of the frog during which structural order, as judged from low-angle x-ray diffraction, was preserved by means of partial cross-linking of the fibers using the zero-length cross-linker 1-ethyl-3-[3-dimethylamino)propyl]carbodiimide. Ten to twenty percent of the myosin cross-bridges were cross-linked, allowing the remaining 80-90% to cycle and generate force. These fibers displayed a well-preserved sarcomeric order and mechanical characteristics similar to those of intact muscle fibers. The intensity of the brightest meridional reflection at 14.5 nm, resulting from the projection of cross-bridges evenly spaced along the myofilament length, decreased by 60% as a relaxed fiber was deprived of ATP and entered the rigor state. Upon activation of a rigorized fiber by the addition of ATP, the intensity of this reflection returned to 97% of the relaxed value, suggesting that the overall orientation of cross-bridges in the active muscle was more perpendicular to the filament axis than in rigor. Following a small-amplitude length step applied to the active fibers, the reflection intensity decreased for both releases and stretches. In rigor, however, a small stretch increased the amplitude of the reflection by 35%. These findings show the close link between cross-bridge orientation and tension changes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actins / chemistry
  • Animals
  • Biomechanical Phenomena
  • Biophysical Phenomena
  • Biophysics
  • Chickens
  • Creatine Kinase / metabolism
  • Cross-Linking Reagents
  • Ethyldimethylaminopropyl Carbodiimide
  • In Vitro Techniques
  • Molecular Structure
  • Muscle Contraction / physiology*
  • Muscle Fibers, Skeletal / chemistry
  • Muscle Fibers, Skeletal / physiology
  • Muscle, Skeletal / chemistry
  • Muscle, Skeletal / physiology*
  • Myosins / chemistry
  • Rana temporaria
  • X-Ray Diffraction


  • Actins
  • Cross-Linking Reagents
  • Creatine Kinase
  • Myosins
  • Ethyldimethylaminopropyl Carbodiimide