6] Monitoring protein conformational changes during membrane fusion

Abstract

This chapter discusses on the various procedures for detection of protein conformational change and exposure of hydrophobic regions during membrane fusion. These procedures can be roughly classified into biophysical, biochemical, and immunological methods. Procedures for the detection of the penetration of hydrophobic segments of proteins into bilayer membranes occurring through conformational changes are also outlined. Protein conformational changes and membrane insertion are usually detected under conditions that trigger membrane fusion. Protein conformational changes are reflected most directly by circular dichroism (CD) spectra: CD spectra in the far- and near-ultraviolet regions are sensitive to changes in peptide backbone structure and the conformation around aromatic groups. Ultraviolet spectra in the near-ultraviolet regions are also sensitive to conformational changes around aromatic amino acid residues: red and blue spectral shifts are observed on perturbation of tyrosine and/or tryptophan residues by a solvent, and on their exposure to a more polar environment.