TY - JOUR
T1 - How aggregation and conformational scrambling of unfolded states govern fluorescence emission spectra
AU - Duy, C.
AU - Fitter, J.
PY - 2006/5
Y1 - 2006/5
N2 - In a case study on five homologous α-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 (λmax) 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 α-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.
AB - In a case study on five homologous α-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 (λmax) 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 α-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.
KW - Dimerization
KW - Multiprotein Complexes/analysis
KW - Protein Conformation
KW - Protein Denaturation
KW - Protein Folding
KW - Spectrometry, Fluorescence/methods
KW - Structure-Activity Relationship
KW - Temperature
KW - alpha-Amylases/analysis
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UR - https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=purepublist2023&SrcAuth=WosAPI&KeyUT=WOS:000236901400033&DestLinkType=FullRecord&DestApp=WOS
U2 - 10.1529/biophysj.105.078980
DO - 10.1529/biophysj.105.078980
M3 - Article
C2 - 16500981
SN - 0006-3495
VL - 90
SP - 3704
EP - 3711
JO - Biophysical Journal
JF - Biophysical Journal
IS - 10
ER -