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Polymers and Self Assembly: From Biology to Nanomaterials Poster Session II
15-POS
Board 15
Thermal Stability and Self-Assembly of Lysozyme in Water-Miscible Ionic Liquids
Diana Fedunova
, Andrea Antosova, Jozef Marek, Erna Demjen, Zuzana Gazova.
Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia.
Ionic liquids (ILs) are widely used as novel solvents in many areas. The water miscible ILs can
serve as effective participants in various biological processes. The major advantage of ILs is that
their physicochemical properties can be tuned by appropriate combination of cations and anions
in order to obtain solvent with desired properties. We have studied effect of imidazolium-based
ionic liquids with acetate and tetrafluoroborate as anions on thermal stability of lysozyme and
morphology of amyloid fibrils using calorimetry, circular dichroism spectroscopy, AFM and
computer image analysis. The reduction of thermal stability of lysozyme is observed at the
presence of either ILs in concentration range 1-8% w/w in 2 mM glycine buffer, pH 2.7. The
transition temperature and ΔHc decreases at all studied ILs concentrations comparing to neat
lysozyme, but denaturation process is still highly reversible. The decrease of ΔHc indicates the
depletion of native structure at the presence of either ILs. We have shown that ionic liquids with
imidazolium as cation and chaotropic anion tetrafluoroborate or kosmoptropic anion acetate
decrease stability of lysozyme at acidic pH conditions with only slightly stronger effect of
chaotropic ion suggesting more complicated mechanism than simplistic Hofmeister phenomena.
We exploited obtained results for study of effect of both ILs on lysozyme fibrillization at the
same conditions. Lysozyme at low protein concentration doesn’t form fibrils at acidified water.
Addition of either ILs leads to formation of lysozyme fibrils, with slightly slower kinetics of
fibrillization at the presence of acetate ions comparing to tetrafluoroborate and different
morphology. Even if tetrafluoroborate-promoted fibrils are matured in shorter time, wider
spectrum of fibril types is observed.
Acknowledgements. This work was supported by research grants from the Slovak Grant Agency
VEGA, 0176, 0181, 0175, ESF 26110230097 and APVV 0526-11.