How aggregation and conformational scrambling of unfolded states govern fluorescence emission spectra Academic Article uri icon


MeSH Major

  • Multiprotein Complexes
  • Spectrometry, Fluorescence
  • alpha-Amylases


  • In a case study on five homologous alpha-amylases we analyzed the properties of unfolded states as obtained from treatments with GndHCl and with elevated temperatures. In particular the wavelength of the tryptophan fluorescence emission peak (lambda(max)) is a valuable parameter to characterize properties of the unfolded state. In all cases with a typical red shift of the emission spectrum occurring during structural unfolding we observed a larger magnitude of this shift for GndHCl-induced unfolding as compared to thermal unfolding. Although a quantitative relation between aggregation and reduction of the unfolding induced red shifts cannot be given, our data indicate that protein aggregation contributes significantly to smaller magnitudes of red shifts as observed during thermal unfolding. In addition, other properties of the unfolded states, most probable structural compactness or simply differences in the conformational scrambling, also affect the magnitude of red shifts. For the irreversible unfolding alpha-amylases studied here, transition temperatures and magnitudes of red shifts are strongly depending on heating rates. Lower protein concentrations and smaller heating rates lead to larger red shifts upon thermal unfolding, indicating that under these conditions the protein aggregation is less pronounced.

publication date

  • January 2006



  • Academic Article



  • eng

PubMed Central ID

  • PMC1440751

Digital Object Identifier (DOI)

  • 10.1529/biophysj.105.078980

PubMed ID

  • 16500981

Additional Document Info

start page

  • 3704

end page

  • 11


  • 90


  • 10