Evidence for head-head interactions in myosin from cardiac and skeletal muscles

  • M. C. Schaub
  • J. G. Watterson
  • P. G. Waser
Conference paper

Summary

1. Binding of Mg-ADP to both heart and fast skeletal myosin was found with 3 methods to proceed in 2 steps. One mole of Mg-ADP binds with high affinity (K ≈ 106 M-1) and subsequently a second with lower affinity (K ≈ 102−104 M-1) per myosin. Only one mole of Mg-ADP was found to bind with the high affinity to isolated myosin heads. This implies that binding of Mg-ADP to intact myosin exhibits negative cooperativity.

2. When a nucleotide is bound, the 2 heads of a single myosin molecule adopt different conformations since on each head a different type of essential thiol group was found to be the most reactive towards N-ethylmaleimide. In the presence of Mg-pyrophosphate a thiol-1 is the most reactive essential group in both heads. Therefore, the nucleoside moiety seems to be required for this latter type of head-head interaction.

Wechselwirkungen zwischen den beiden Köpfen in Myosin aus Herz- und Skelettmuskeln

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Copyright information

© Dr. Dietrich Steinkopff Verlag, Darmstadt 1977

Authors and Affiliations

  • M. C. Schaub
    • 1
  • J. G. Watterson
    • 1
  • P. G. Waser
    • 1
  1. 1.Institute of PharmacologyUniversity of ZürichZürichSwitzerland

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