Nucleotide analogue induces global and local changes in muscle fibres

D. Lrinczy, N. Hartvig, J. Belágyi

Research output: Contribution to journalConference article

10 Citations (Scopus)

Abstract

The effect of AMP.PNP on the thermal stability and dynamics of myosin head were investigated by using DSC and different spin label technique for chemically skinned muscle fibres prepared from rabbit. The thermal unfolding of the fibres in rigor, strong as well as weak-binding state showed a complex process characterizing at least three discrete domain regions with different stability (Tm=54, 58.4 and 62.3°C). The unfolding at 54°C refers to the catalytic domain of myosin, whereas transition at Tm=58.4°C represents the rod-like region. In the presence of AMP.PNP only the parameters of the last transition changed significantly (Tm=70.4°C) showing an increased interaction between actin and myosin heads being attached to actin. Measurements on MSL-fibres (labelled at Cys-707 of myosin) in the presence of AMP.PNP showed that about half of the cross-bridges dissociated from actin. This fraction had a dynamic disorder, the other population had the same spectral feature as in rigor. In contrast, on TCSL-fibres AMP.PNP increased the orientational disorder of myosin heads, a random population of spin labels was superimposed on the ADP-like spectrum showing conformational and motional changes in the internal structure of myosin heads. ST EPR measurements reported increased rotational mobility of spin labels in the presence of AMP.PNP. The DSC and EPR results suggest that in the presence of AMP.PNP the attached heads have the same global orientation as in rigor, but the internal structure undergoes a local conformational change.

Original languageEnglish
Pages (from-to)651-658
Number of pages8
JournalJournal of Thermal Analysis and Calorimetry
Volume64
Issue number2
DOIs
Publication statusPublished - Oct 1 2001
Event12th International Congress on Thermal Analysis and Calorimetry - Conpenhagen, Denmark
Duration: Aug 14 2000Aug 18 2000

Keywords

  • DSC
  • EPR
  • MSL
  • Rabbit muscle fibres
  • TCL
  • Thermal stability

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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