02007nas a2200229   4500008004100000022001400041245014800055210006900203260007500272300001400347490000700361520110400368653002501472653002101497653003101518653001401549653001801563100002201581700002601603700001601629856013201645       2016                        eng d  a1439-423500aComparative investigation of the ionicity of aprotic and protic ionic liquids in molecular solvents by using conductometry and NMR spectroscopy0 aComparative investigation of the ionicity of aprotic and protic   aPOSTFACH 101161, 69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcAPR  a1006-10170 v173 a<p>Electrical conductivity (sigma), viscosity (), and self-diffusion coefficient (D) measurements of binary mixtures of aprotic and protic imidazolium-based ionic liquids with water, dimethyl sulfoxide, and ethylene glycol were measured from 293.15 to 323.15K. The temperature dependence study reveals typical Arrhenius behavior. The ionicities of aprotic ionic liquids were observed to be higher than those of protic ionic liquids in these solvents. The aprotic ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, [bmIm][BF4], displays 100% ionicity in both water and ethylene glycol. The protic ionic liquids in both water and ethylene glycol are classed as good ionic candidates, whereas in DMSO they are classed as having a poor ionic nature. The solvation dynamics of the ionic species of the ionic liquids are illustrated on the basis of the (HNMR)-H-1 chemical shifts of the ionic liquids. The self-diffusion coefficients D of the cation and anion of [HmIm][CH3COO] in D2O and in [D-6]DMSO are determined by using H-1 nuclei with pulsed field gradient spin-echo NMR spectroscopy.</p>10aconducting materials10aElectrochemistry10aelectrostatic interactions10aIon pairs10aionic liquids1 aThawarkar, Sachin1 aKhupse, Nageshwar, D.1 aKumar, Anil  uhttps://library.ncl.res.in/content/comparative-investigation-ionicity-aprotic-and-protic-ionic-liquids-molecular-solvents-using02266nas a2200217   4500008004100000022001400041245010100055210006900156260000800225300001100233490000800244520150100252653003101753653003001784653002801814653002201842100001901864700001701883700002401900856012401924       2021                        eng d  a0301-462200apH-dependent protein stability switch coupled to the perturbed pKa of a single ionizable residue0 apHdependent protein stability switch coupled to the perturbed pK  cJUL  a1065910 v2743 a<p>The contribution of electrostatic interactions in protein stability has not been fully understood. Burial of an ionizable amino acid inside the hydrophobic protein core can affect its ionization equilibrium and shift its pKa differentially in the native (N) and unfolded (U) states of a protein and this coupling between the folding/ unfolding cycle and the ionization equilibria of the ionizable residue can substantially influence the protein stability. Here, we studied the coupling of the folding/unfolding cycle with the ionization of a buried ionizable residue in a multi-domain protein, Human Serum Albumin (HSA) using fluorescence spectroscopy. A pHdependent change in the stability of HSA was observed in the near native pH range (pH 6.0-9.0). The protonation-deprotonation equilibrium of a single thiol residue that is buried in the protein structure was identified to give rise to the pH-dependent protein stability. We quantified the pKa of the thiol residue in the N and the U states. The mean pKa of the thiol in the N state was upshifted by 0.5 units to 8.7 due to the burial of the thiol in the protein structure. Surprisingly, the mean pKa of the thiol in the U state was observed to be downshifted by 1.3 units to 6.9. These results indicate that some charged residues are spatially proximal to the thiol group in the U state. Our results suggest that, in addition to the N state, electrostatic interactions in the U state are important determinants of protein stability.</p>10aelectrostatic interactions10aFluorescence spectroscopy10aThermodynamic stability10aUnfolded proteins1 aMishra, Prajna1 aPatni, Divya1 aJha, Santosh, Kumar  uhttps://library.ncl.res.in/content/ph-dependent-protein-stability-switch-coupled-perturbed-pka-single-ionizable-residue