Nucleotides induced changes in skeletal muscle myosin by DSC, TMDSC and EPR

D. Lőrinczy, F. Könczöl, L. Farkas, J. Belágyi, C. Schick

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Electron paramagnetic resonance (EPR, ST-EPR) and differential scanning calorimetry (DSC) were used in conventional and temperature modulated mode to study internal motions and energetics of myosin in skeletal muscle fibres in different states of the actomyosin ATPase cycle. Psoas muscle fibres from rabbit were spin-labelled with an isothiocyanate-based probe molecule at the reactive sulfhydryl site (Cys-707) of the catalytic domain of myosin. In the presence of nucleotides (ATP, ADP, AMP·PNP) and ATP or ADP plus orthovanadate, the conventional EPR spectra showed changes in the ordering of the probe molecules in fibres. In MgADP state a new distribution appeared; ATP plus orthovanadate increased the orientational disorder of myosin heads, a random population of spin labels was superimposed on the ADP-like spectrum. In the complex DSC pattern, higher transition referred to the head region of myosin. The enthalpy of the thermal unfolding depended on the nucleotides, the conversion from a strongly attached state of myosin to actin to a weakly binding state was accompanied with an increase of the transition temperature which was due to the change of the affinity of nucleotide binding to myosin. This was more pronounced in TMDSC mode, indicating that the strong-binding state and rigor state differ energetically from each other. The different transition temperatures indicated alterations in the internal microstructure of myosin head region. The monoton decreasing TMDSC heat capacities show that Cp of biological samples should not be temperature independent.

Original languageEnglish
Pages (from-to)633-644
Number of pages12
JournalJournal of Thermal Analysis and Calorimetry
Volume66
Issue number2
DOIs
Publication statusPublished - 2001

Fingerprint

Skeletal Muscle Myosins
myosins
skeletal muscle
nucleotides
Myosins
Nucleotides
Administrative data processing
Paramagnetic resonance
Muscle
Differential scanning calorimetry
Adenosinetriphosphate
heat measurement
scanning
adenosine diphosphate
adenosine triphosphate
Adenosine Diphosphate
Superconducting transition temperature
Fibers
muscle fibers
Molecules

Keywords

  • DSC
  • EPR
  • Nucleotides
  • Skeletal muscle contraction
  • Temperature modulated calorimetry

ASJC Scopus subject areas

  • Chemical Engineering(all)

Cite this

Nucleotides induced changes in skeletal muscle myosin by DSC, TMDSC and EPR. / Lőrinczy, D.; Könczöl, F.; Farkas, L.; Belágyi, J.; Schick, C.

In: Journal of Thermal Analysis and Calorimetry, Vol. 66, No. 2, 2001, p. 633-644.

Research output: Contribution to journalArticle

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AU - Schick, C.

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