22113-86-6Relevant academic research and scientific papers
Structure-energy relations in hen egg white lysozyme observed during refolding from a quenched unfolded state
Cho, Theresa Y.,Byrne, Nolene,Moore, David J.,Pethica, Brian A.,Austen Angell,Debenedetti, Pablo G.
, p. 4441 - 4443 (2009)
We use infrared spectroscopy to study the evolution of protein folding intermediate structures on arbitrarily slow time scales by rapidly quenching thermally unfolded hen egg white lysozyme in a glassy matrix, followed by reheating of the protein to refold; upon comparison with differential scanning calorimetric experiments, low-temperature structural changes that precede the formation of energetic native contacts are revealed. The Royal Society of Chemistry 2009.
Enhanced solubilization of membrane proteins by alkylamines and polyamines
Yasui, Kazutoshi,Uegaki, Masamichi,Shiraki, Kentaro,Ishimizu, Takeshi
, p. 486 - 493 (2010)
Around 25% of proteins in living organisms are membrane proteins that perform many critical functions such as synthesis of biomolecules and signal transduction. Membrane proteins are extracted from the lipid bilayer and solubilized with a detergent for biochemical characterization; however, their solubilization is an empirical technique and sometimes insufficient quantities of proteins are solubilized in aqueous buffer to allow characterization. We found that addition of alkylamines and polyamines to solubilization buffer containing a detergent enhanced solubilization of membrane proteins from microsomes. The solubilization of polygalacturonic acid synthase localized at the plant Golgi membrane was enhanced by up to 9.9-fold upon addition of spermidine to the solubilization buffer. These additives also enhanced the solubilization of other plant membrane proteins localized in other organelles such as the endoplasmic reticulum and plasma membrane as well as that of an animal Golgi-localized membrane protein. Thus, addition of alkylamines and polyamines to solubilization buffer is a generally applicable method for effective solubilization of membrane proteins. The mechanism of the enhancement of solubilization is discussed. Published by Wiley-Blackwell.
Volumetric properties of ethylammonium nitrate + γ-butyrolactone binary systems: Solvation phenomena from density and raman spectroscopy
Zarrougui, Ramzi,Dhahbi, Mahmoud,Lemordant, Daniel
, p. 1531 - 1548 (2010)
The densities of binary mixtures of ethylammonium nitrate (EAN) ionic liquid (IL) and γ-butyrolactone (BL) have been measured over the entire range of concentrations at 293.15, 298.15, 303.15, 308.15, 313.15 and 318.15 K and under ambient pressure. Experimental densities were used to calculate excess molar volumes VmE, isobaric and excess isobaric expansion coefficients α and α E. The excess molar volumes have both negative and positive values, while the excess isobaric expansion coefficients are negative over the entire composition range. The V mE values have been fitted to the Redlich-Kister polynomial equation, and other volumetric properties such as the partial molar volumes V mi, the excess partial molar volume Vmi E and the partial molar volumes at infinite dilution V miE were calculated. The results have been interpreted in terms of dipole-dipole interactions, hydrogen bonds formation and structural factors of these mixtures. The FT-Raman spectroscopy study of the intensity variations of some characteristic bands such as the C=O stretching band at 1763 cm-1, C-O symmetric stretching band at 932 cm-1 and C-C stretching band at 872 cm-1 of BL has been undertaken. The solvation phenomenon is evidenced by the modifications of these band intensities due to the presence of the IL ions. Moreover, the Raman spectroscopy corroborates the volumetric study. The average number of BL molecules in the primary solvation shell of the ethylammonium cation lies between 3 and 4 depending on the temperature.
Aggregation behavior of long-chain piperidinium ionic liquids in ethylammonium nitrate
Dai, Caili,Du, Mingyong,Liu, Yifei,Wang, Shilu,Zhao, Jianhui,Chen, Ang,Peng, Dongxu,Zhao, Mingwei
, p. 20157 - 20169 (2014)
Micelles formed by the long-chain piperidinium ionic liquids (ILs) N-alkyl-N-methylpiperidinium bromide of general formula CnPDB (n = 12, 14, 16) in ethylammonium nitrate (EAN) were investigated through surface tension and dissipative particle dynamics (DPD) simulations. Through surface tension measurements, the critical micelle concentration (cmc), the effectiveness of surface tension reduction (Πcmc), the maximum excess surface concentration (Λmax) and the minimum area occupied per surfactant molecule (Amin) can be obtained. A series of thermodynamic parameters (ΔG0m, ΔH0m and ΔS0m) of micellization can be calculated and the results showed that the micellization was entropy-driven. In addition, the DPD simulation was performed to simulate the whole aggregation process behavior to better reveal the micelle formation process.
Measurements and correlation of viscosity and conductivity for the mixtures of ethylammonium nitrate with organic solvents
Litaeim, Yousra,Dhahbi, Mahmoud
, p. 42 - 50 (2010)
Transport physicochemical properties of binary mixtures ionic liquid/organic solvent (IL/OS) were studied. Systematical measurements of viscosities (η) and conductivities (Λ) for the binary mixtures of ethylammonium nitrate (EAN) with different OS, over the whole composition range and at temperature ranging from 273.15 K to 313.15 K, were performed. The variation tendency of viscosities/conductivities with composition of the mixtures was explained through the disruption of molecular solutes to ionic association or aggregation of the ionic liquids and correlation between them is carried out by means of Walden product (W). A semi-empirical equation proposed by Jones and Dole was used to describe the variation of viscosity with salt concentration (C). At low concentration of EAN, molar conductivity follows cube root law predicted by the quasi-lattice model. The two transport processes are well described by Arrhenius type laws from which the activation energies for the viscosity (Ea,η) and conductivity (Ea,Λ) are deduced.
Reversible Photoresponsive Molecular Alignment of Liquid Crystals at Fluid Interfaces with Persistent Stability
Tian, Tongtong,Hu, Qiongzheng,Wang, Yi,Gao, Yanan,Yu, Li
, p. 6340 - 6344 (2016)
This work demonstrates a noninvasive approach to control alignment of liquid crystals persistently and reversibly at fluid interfaces by using a photoresponsive azobenzene-based surfactant dissolved in an ionic liquid (IL), ethylammonium nitrate (EAN). As the first report on the orientational behavior of LCs at the IL/LC interface, our study also expands current understanding of alignment control of LCs at the aqueous/LC interface by adding electrolytes into aqueous solutions. The threshold concentration for switching the optical responses of LCs can be changed just by simply manipulating the ratio of EAN to H2O. This work will inspire fundamental studies and novel applications of using the LC-based imaging technique to investigate various chemical and biological events in ILs.
Anhydrous proton exchange membranes at elevated temperatures: Effect of protic ionic liquids and crosslinker on proton conductivity
Yang, Yi,Gao, Hejun,Zheng, Liqiang
, p. 17683 - 17689 (2015)
A series of novel anhydrous proton exchange membranes (poly(vinyl alcohol)-citric acid-ionic liquid (PVA-CA-IL)) were prepared using the low cost ionic liquids ethylammonium nitrate (EAN), diethylammonium nitrate (DEAN), and triethylammonium nitrate (TEAN) as conductive fillers in PVA support membrane. The properties of the PVA-CA-IL membranes can be controlled by changing the molar ratio of the PVA, ILs and CA. The thermal stability of PVA-CA-IL membrane was measured by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and the microstructure was investigated using scanning electron microscopy (SEM) and the Anton-paar SAX Sess mc2 system (SAXS). The effects of temperature, ILs and crosslinker dosage on proton conductivity were also systematically investigated. The results showed that the PVA-CA-IL membranes had excellent performance. The proton conductivity of PVA-CA-EAN (mole ratio = 1:0.05:0.4) could reach up to 7.8 mS cm-1 at 140 °C. The introduction of ionic liquid into PVA membrane constituted a new and efficient kind of anhydrous proton exchange membrane. This journal is
Liquid crystalline phases of the amphiphilic ionic liquid n -hexadecyl- n -methylpyrrolidinium bromide formed in the ionic liquid ethylammonium nitrate and in water
Zhao, Mingwei,Gao, Yanan,Zheng, Liqiang
, p. 11382 - 11389 (2010)
The phase behavior of a surfactant-like ionic liquid, N-hexadecyl-N- methylpyrrolidinium bromide (C16MPB), was studied in both water and a room temperature ionic liquid, ethylammonium nitrate (EAN). Polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements were employed to investigate the phase behavior of the two systems and to determine which lyotropic liquid crystalline (LC) phases were formed. With increasing C16MPB concentration, an isotropic solution phase, a hexagonal (H1) phase, and a cubic phase (V2) are all present in either EAN or H2O. The structural parameters of the H1 phase were calculated from SAXS patterns, which show the structural changes as a function of the amount of C16MPB. The rheological results reveal that the H1 phase constructed by C16MPB in EAN displays a typical Maxwell behavior, whereas the H1 phase formed by C 16MPB in water shows a gel-like behavior, unlike traditional cationic surfactants. POM and differential scanning calorimetry (DSC) results demonstrate that the lyotropic LC phase in EAN has a higher thermal stability than that formed in H2O, which may be important to extend the applications of the LC phase.
First fluorinated zwitterionic micelle with unusually slow exchange in an ionic liquid
Wang, Xiaolin,Long, Panfeng,Dong, Shuli,Hao, Jingcheng
, p. 14380 - 14385 (2013)
The micellization of a fluorinated zwitterionic surfactant in ethylammonium nitrate (EAN) was investigated. The freeze-fracture transmission electron microscope (FF-TEM) observations confirm the formation of spherical micelles with the average diameter 25.45 ± 3.74 nm. The micellization is an entropy-driven process at low temperature but an enthalpy-driven process at high temperature. Two sets of 19F NMR signals above the critical micelle concentration (cmc) indicate that the unusually slow exchange between micelles and monomers exists in ionic liquid; meanwhile, surfactant molecules are more inclined to stay in micelle states instead of monomer states at higher concentration. Through the analysis of the half line width (Δν 1/2), we can obtain the kinetic information of fluorinated zwitterionic micellization in an ionic liquid.
Enhanced photo-electrochemical water oxidation on MnOx in buffered organic/inorganic electrolytes
Zhou, Fengling,McDonnell-Worth, Ciaran,Li, Haitao,Li, Jiaye,Spiccia, Leone,MacFarlane, Douglas R.
, p. 16642 - 16652 (2015)
Manganese oxide (MnOx) materials have been widely studied as electro-catalysts for the water oxidation reaction. Although the electronic structure of MnO2 (band gap ～2 eV) indicates it could be a promising photo-anode material for solar water splitting, so far only quite small photocurrents have been obtained from manganese oxides. Here, we show that the photo-electrochemical water oxidation performance of MnOx films can be significantly improved by using buffered aqueous electrolytes containing amine ionic liquids. The buffered conditions to maintain a constant proton activity and the amine salt are both crucial for achieving high photocurrents. Photocurrents as high as 4.5 mA cm-2 were obtained at 1.0 V vs. SCE (η = 540 mV) in Bi buffered n-butylammonium nitrate (BAN) electrolyte at pH 9. The incident photon-to-current efficiency (IPCE) was found to be greater than 3% at 400 nm and 4% at 370 nm. Both H2O2 and O2 are produced simultaneously in this system, with the potential subsequent decomposition of the H2O2 to form oxygen. An acceleration of the decomposition of H2O2 under illumination is proposed to explain the photocurrent improvement.
