Intrinsic coordination for revealing local structural changes in protein folding-unfolding

Phys Chem Chem Phys. 2016 Jan 28;18(4):3179-87. doi: 10.1039/c5cp06309d.

Abstract

With a deformed object of a rigid rod inside, the local dislocations may be tracked relatively easily with respect to the internal rigid rod. We apply this concept on protein folding-unfolding to track the internal structural changes of an unfolded protein in solution. Proposed here is a protein internal coordination based on the major axis X of an ellipsoidal protein and the stable intrinsic transition dipole moment μ of the protein during unfolding. In this methodology, small-angle X-ray scattering (SAXS) is used to provide the protein global morphologies in the native and unfolded states. Furthermore, time-resolved fluorescence anisotropy (TRFA) provides the relative orientation between X and μ of Trp59 of the model protein cytochrome c. Hence observed in the protein unfolding with denaturants, acid, urea, or GuHCl, is the elongation of the native protein conformation along a reoriented protein major axis; accompanied are the different extents of relocations of the terminal α helices and loop structures of the protein in the corresponding unfolding.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cytochromes c / chemistry*
  • Horses
  • Protein Conformation
  • Protein Folding
  • Quantum Theory
  • Scattering, Small Angle
  • X-Ray Diffraction

Substances

  • Cytochromes c