Biophysical Society Thematic Meeting - October 25-30, 2015

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.

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