Effects of nucleotide on skeletal muscle myosin unfolding in myofibrils by DSC

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Abstract

The thermal unfolding of myosin in skeletal muscle myofibrils was studied by differential scanning calorimetry (DSC). In the absence of nucleotide two major transitions with Tm of 52°C and 58°C, and a minor transition with Tm of 19°C were detected The unfolding can be characterized with a total enthalpy of -90±6.1 mJ/g protein. The major transition with Tm of 58°C was independent of the presence of nucleotide and orthovanadate (Vi), and it can be assigned to the unfolding of the α-helical rod part of myosin and partly to actin. In the presence of MgADP. the minor transition shifted to higher temperature, indicating changes between the heavy chain of subfragment-1 and the LC-2 light chain. The transition with Tm of 52°C exhibited a significant broadening and a small shift to lower temperature. It indicates an internal domain or segmental rearrangement of the myosin motor. Upon addition of MgADP and Vi, a shift to higher temperature was observed for the lower major transition, evidencing that with trapped ADP and Vi the intermolecular interactions stabilized the myosin head region.

Original languageEnglish
Pages (from-to)592-598
Number of pages7
JournalBiochemical and biophysical research communications
Volume217
Issue number2
DOIs
Publication statusPublished - Dec 14 1995

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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