@article { ISI:000373738200010,
	title = {Comparative investigation of the ionicity of aprotic and protic ionic liquids in molecular solvents by using conductometry and NMR spectroscopy},
	journal = {Chemphyschem},
	volume = {17},
	number = {7},
	year = {2016},
	month = {APR},
	pages = {1006-1017},
	publisher = {WILEY-V C H VERLAG GMBH},
	address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY},
	abstract = {<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>},
	keywords = {conducting materials, Electrochemistry, electrostatic interactions, Ion pairs, ionic liquids},
	issn = {1439-4235},
	doi = {10.1002/cphc.201501156},
	author = {Thawarkar, Sachin and Khupse, Nageshwar D. and Kumar, Anil}
}
@article {47344,
	title = {pH-dependent protein stability switch coupled to the perturbed pKa of a single ionizable residue},
	journal = {Biophysical Chemistry},
	volume = {274},
	year = {2021},
	month = {JUL},
	pages = {106591},
	type = {Article},
	abstract = {<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>},
	keywords = {electrostatic interactions, Fluorescence spectroscopy, Thermodynamic stability, Unfolded proteins},
	issn = {0301-4622},
	doi = {10.1016/j.bpc.2021.106591},
	author = {Mishra, Prajna and Patni, Divya and Jha, Santosh Kumar}
}
