Nucleotide dependent differences between the α-skeletal and α-cardiac actin isoforms

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The thermodynamic properties of the actin filaments prepared from cardiomyocytes were investigated with differential scanning calorimetry. This method could distinguish between the α-cardiac and α-skeletal components of the actin filaments polymerised from ADP-actin monomers by their different melting temperatures (Tm). Similar separation was not possible with filaments polymerised from ATP-actin monomers. Further analyses revealed that the activation energy (Eact) was greater for filaments of α-skeletal actin than for α-cardiac actin monomers when the filaments were polymerised from ADP-actin monomers. These results showed that the α-cardiac actin filaments were thermodynamically less stable than the filaments of α-skeletal actin and their difference was nucleotide dependent. Based on these results and considering previous observations it was concluded that the existence of two actin isoforms and their nucleotide dependent conformational differences are part of the tuning regulatory mechanism by which the cardiac muscle cells can maintain their biological function under pathological conditions.

Original languageEnglish
Pages (from-to)696-702
Number of pages7
JournalBiochemical and biophysical research communications
Issue number3
Publication statusPublished - Apr 11 2008



  • Actin filament
  • Calorimetry
  • Nucleotides
  • Protein conformation
  • Stability
  • Thermodynamics

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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