01957nas a2200169 4500008004100000022001400041245011000055210006900165260007100234300001600305490000800321520128000329100001801609700002301627700001601650856012101666 2010 eng d a1520-610600aTemperature effect on the molecular interactions between ammonium ionic liquids and N,N-dimethylformamide0 aTemperature effect on the molecular interactions between ammoniu a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a13415-134250 v1143 a

In view of the wide scope of molecular interactions between the highly polar compound of N,N-dimethylformamide (DMF) and ammonium ionic liquids (ILs), we have measured thermophysical properties such as densities (rho) and ultrasonic sound velocities (u) over the whole composition range at temperatures ranging from 25 to 50 degrees C under atmospheric pressure. To gain some insight into the several aggregations of molecular interactions present in these mixed solvents, we predicted the excess molar volume (V(E)) and the deviations in isentropic compressibilities (Delta K(s)) as a function of the concentration of IL. These results are fitted to the Redlich-Kister polynomials. The materials investigated in the present study included the hydroxide series of ammonium ILs of tetramethylammonium hydroxide [(CH(3))(4)N][OH] (TMAH), tetraethylammonium hydroxide [(C(2)H(5))(4)N][OH] (TEAH), and tetrapropylammonium hydroxide [(C(2)H(7))(4)N][OH] (TPAH). The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties. A qualitative analysis of the results is discussed in terms of the ion-dipole and ion-pair interactions, and hydrogen bonding between ILs and DMF molecules and their structural factors.

1 aAttri, Pankaj1 aVenkatesu, Pannuru1 aKumar, Anil uhttps://library.ncl.res.in/content/temperature-effect-molecular-interactions-between-ammonium-ionic-liquids-and-nn-002337nas a2200169 4500008004100000022001400041245012700055210006900182260011000251300001400361490000700375520160000382100001801982700002302000700001602023856012802039 2011 eng d a1463-907600aActivity and stability of alpha-chymotrypsin in biocompatible ionic liquids: enzyme refolding by triethyl ammonium acetate0 aActivity and stability of alphachymotrypsin in biocompatible ion aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcFEB a2788-27960 v133 a

In view the of wide scope of structural information of biomolecules in biocompatible ionic liquids (ILs) in various applications including chemical and biochemical, it is essential to study the productive preferential interactions between biological macromolecules and biocompatible ILs. We have therefore explored the stability and activity of alpha-chymotrypsin (CT) in the presence of five ILs from different families, such as triethyl ammonium acetate (TEAA), triethyl ammonium phosphate (TEAP) from ammonium salts, 1-benzyl-3-methylimidazolium chloride ([Bzmim][Cl]), 1-benzyl-3-methylimidazolium tetrafluoroborate ([Bzmim][BF(4)]) from imidazolium salts and tetra-butyl phosphonium bromide (TBPBr) from phosphonium families. Circular dichroism (CD) and UV-vis spectrophotometer experiments were used to study CT stabilization by ILs, related to the associated structural changes and enzyme activity studies, respectively. We observed that all ILs have a dominant contribution to the stabilization of CT. The stability and activity of CT depends on the structural arrangement of the ions of ILs. Our experimental results explicitly elucidate that more hydrophobic imidazolium and phosphonium cations carrying longer alkyl chains of ILs ([Bzmim][Cl], [Bzmim][BF(4)] and TBPBr) were weak stabilizers for CT, while small alkyl chain molecules of triethyl ammonium salts (TEAA and TEAP) are strong stabilizers and therefore more biocompatible for CT stability. Our CD and NMR measurements reveal that TEAA is a refolding additive for CT from a quenched thermal unfolded enzyme structure.

1 aAttri, Pankaj1 aVenkatesu, Pannuru1 aKumar, Anil uhttps://library.ncl.res.in/content/activity-and-stability-alpha-chymotrypsin-biocompatible-ionic-liquids-enzyme-refolding-000945nas a2200181 4500008004100000022001400041245008900055210006900144260011000213300001600323490000700339520022600346100001800572700002300590700001600613700001800629856011600647 2011 eng d a1463-907600aProtic ionic liquid attenuates the deleterious actions of urea on alpha-chymotrypsin0 aProtic ionic liquid attenuates the deleterious actions of urea o aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcSEP a17023-170260 v133 a

We present a biocompatible ionic liquid, triethyl ammonium acetate (TEAA), that attenuates the denaturation action of a non-ionic chaotrope, urea, on the industrially relevant proteolytic enzyme alpha-chymotrypsin.

1 aAttri, Pankaj1 aVenkatesu, Pannuru1 aKumar, Anil1 aByrne, Nolene uhttps://library.ncl.res.in/content/protic-ionic-liquid-attenuates-deleterious-actions-urea-alpha-chymotrypsin-001172nas a2200181 4500008004100000022001400041245010900055210006900164260011000233300001600343490000700359520042200366100001900788700001800807700002300825700001600848856012600864 2014 eng d a1463-907600aQuantitative evaluation of the ability of ionic liquids to offset the cold-induced unfolding of proteins0 aQuantitative evaluation of the ability of ionic liquids to offse aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJUN a15806-158100 v163 a

Significant non-reversible two-state denaturation was observed for proteins such as myoglobin (Mb) and alpha-chymotrypsin (CT) with decreasing temperature in the presence of 1-butyl-3-methylimidazolium-based ([C(4)mim]X-+(-)) ionic liquids (ILs) with various anions (X-). Interestingly, for the first time, ILs having acetate and bromide anions were proven to counteract the cold-induced unfolding of proteins.

1 aKumar, Awanish1 aRani, Anjeeta1 aVenkatesu, Pannuru1 aKumar, Anil uhttps://library.ncl.res.in/content/quantitative-evaluation-ability-ionic-liquids-offset-cold-induced-unfolding-proteins-0