Helical hydrophobic moment profiles in α and β tropomyosin

Averaged helical hydrophobic moment ratios have been evaluated in order to asses the potential of amphiphilic regions contributing to the helix-helix interaction responsible for stabilization of tropomyosin dimers. These ratios yield profiles that are higher in the amino-terminal half than in the carboxyl-terminal half of α and β tropomyosin chains. The higher profiles found in the amino-terminal half of α tropomyosin may contribute to the greater stability of the dimer in this region. Especially small helical hydrophobic moment ratios are found for fragments at each chain end and in the interior near Cys 190. These locations have previously been shown to be regions of instability in tropomyosin dimers