Fluoroalcohol-induced structural changes of proteins: some aspects of cosolvent-protein interactions

The conformational transitions of bovine beta-lactoglobulin A and phosphoglycerate kinase from yeast induced by hexafluoroisopropanol (HFIP) and trifluoroethanol (TFE) have been studied by dynamic light scattering and circular dichroism spectroscopy in order to elucidate the potential of fluoroalcoh...

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Bibliographic Details
Published in:European biophysics journal 2001-08, Vol.30 (4), p.273-283
Main Authors: Gast, K, Siemer, A, Zirwer, D, Damaschun, G
Format: Article
Language:English
Subjects:
Animals
Biophysical Phenomena
Biophysics
Cattle
Circular Dichroism
Kinases
Lactoglobulins - chemistry
Light
Molecular Weight
Phosphoglycerate Kinase - chemistry
Propanols
Protein Structure, Secondary
Proteins
Proteins - chemistry
Saccharomyces cerevisiae - enzymology
Scattering, Radiation
Solvents
Trifluoroethanol
Water
Yeast
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Summary:The conformational transitions of bovine beta-lactoglobulin A and phosphoglycerate kinase from yeast induced by hexafluoroisopropanol (HFIP) and trifluoroethanol (TFE) have been studied by dynamic light scattering and circular dichroism spectroscopy in order to elucidate the potential of fluoroalcohols to bring about structural changes of proteins. Moreover, pure fluoroalcohol-water mixed solvents were investigated to prove the relation between cluster formation and the effects on proteins. The results demonstrate that cluster formation is mostly an accompanying phenomenon because important structural changes of the proteins occur well below the critical concentration of fluoroalcohol at which the formation of clusters sets in. According to our light scattering experiments, the remarkable potential of HFIP is a consequence of extensive preferential binding. Surprisingly, preferential binding seems to play a vanishing role in the case of TFE. However, the comparable Stokes radii of both proteins in the highly helical state induced by either HFIP or TFE point to a similar degree of solvation in both mixed solvents. This shows that direct binding or an indirect mechanism must be equally taken into consideration to explain the effects of alcohols on proteins. The existence of a compact helical intermediate with non-native secondary structure on the transition of beta-lactoglobulin A from the native to the highly helical state is clearly demonstrated.
ISSN:0175-7571
1432-1017
DOI:10.1007/s002490100148