A Temperature and Salt-Tolerant <Emphasis Type="SmallCaps">l</Emphasis>-Glutaminase from Gangotri Region of Uttarakhand Himalaya: Enzyme Purification and Characterization

Purification and characterization of halotolerant, thermostable alkaline l-glutaminase from a Bacillus sp. LKG-01 (MTCC 10401), isolated from Gangotri region of Uttarakhand Himalaya, is being reported in this paper. Enzyme has been purified 49-fold from cell-free extract with 25% recovery (specific activity 584.2 U/mg protein) by (NH₄)₂SO₄ precipitation followed by anion exchange chromatography and gel filtration. Enzyme has a molecular weight of 66 kDa. l-Glutaminase is most active at pH 11.0 and stable in the pH range 8.0–11.0. Temperature optimum is 70 °C and is completely stable after 3 h pre-incubation at 50 °C. Enzyme reflects more enhanced activity with 1–20% (w/v) NaCl, which is further reduced to 80% when NaCl concentration was increased up to 25%. l-Glutaminase is almost active with K⁺, Zn²⁺, and Ni²⁺ ions and K _m and V _max values of 240 μM and 277.77 ± 1.1 U/mg proteins, respectively. Higher specific activity, purification fold, better halo-tolerance, and thermostability would make this enzyme more attractive for food fermentation with respect to other soil microbe derived l-glutaminase reported so far.     

Determination of the Association Constants of Charge-Transfer Complexes Between N,N-Diethylaniline and Nitro Explosives Using High Performance Thin Layer Chromatography with Scanning Video Densitometry and Spectrophotometry

Charge-transfer (CT) or electron donor-acceptor (EDA) complex formation between organic donors and acceptors has been extensively studied by spectrophotometry and other methods. High performance thin layer chromatography (HPTLC), although extensively used for the identification and quantification of drugs and explosives, has not been used until now to determine the extent of association and the association constants K _DA of charge transfer or EDA complexes between donor (D) and acceptor (A). This paper describes the use of the HPTLC technique with scanning densitometry to identify and determine the association constants K _DA of charge-transfer complexes of N,N-diethylaniline (DEA) with different nitro explosives, namely 1,4-dinitrobenzene (DNB), 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT), in chloroform. Advantages of the HPTLC method are highlighted. The association constants K _DA of the complexes determined using the HPTLC method have been verified and validated spectrophotometrically when the concentrations of D and A are in their stoichiometric ratio. The thermodynamics of the complex formation reaction were obtained spectrophotometrically from measurements of the association constants K _DA at five different temperatures ranging from 293 to 313 K, when D and A are in their stoichiometric ratio and also when A≫D.     

Thermodynamic properties of Ga27Si3 cluster using density functional molecular dynamics

Density functional molecular dynamical calculations have been carried out to explore the effect of silicon impurities on thermodynamic properties of Ga(30). We have obtained 500 distinct low energy equilibrium geometries of Ga(27)Si(3) in order to obtain reliable ground state geometry. The specific heat has been calculated using multiple histogram techniques and compared with that of Ga(30). We demonstrate that silicon impurities have a dramatic effect on the thermodynamic properties of the host cluster. In contrast to Ga(30), the specific heat of Ga(27)Si(3) shows a clear melting peak at ≈500 K, changing the character of Ga(30) from a nonmelter to a melter.     

Structured products equilibria in conic two price markets

A novel equilibrium theory is developed for two price markets permitting investors to trade personally designed structured products. Classical market clearing is enhanced for structured products where the market allows these products to be freely bought at ask prices or sold for bid prices. Competitive pressures lead the market to lower the ask prices and raise the bid prices with the market offering individual investors the widest possible set of acceptable risks provided the aggregate counter cash flow held by the market is consistent with a more conservative prespecified set of acceptable risks. We learn that in equilibrium heterogeneous investors inherit a common hedging objective of maximizing the bid prices of the final structured product sold to market or equivalently minimizing the ask price of what is bought.     

Synthesis and structural characterization of mixed ligand η-2-hydroxyacetophenone complexes of cobalt(III)

A tridentate Schiff base ligand [(CH₃)₂NCH₂CH₂N=C(CH₃)C₆H₄OH)] (LH) has been synthesized from 2-hydroxyacetophenone and 2-dimethylaminoethylamine. This ligand forms the neutral complexes [Co(L)(N₃){o-(CH₃C=O)C₆H₄O}] (1) and [Co(L)(SCN){o-(CH₃C=O)C₆H₄O}]·1/2H₂O (2) in presence of equivalent amount of Co(II) acetate, and sodium azide for 1 and sodium thiocyanate for 2. The complexes have been characterized by spectroscopic and crystallographic methods. The coordination geometry around Co(III) in both the complexes is distorted octahedral with one tridentate ligand L, one bidentate 2-hydroxyacetophenone and one monodentate azide for 1 and thiocyanate for 2. The azide and thiocyanate ligands in the two complexes occupy different positions relative to the coordination sites of L.     

New Mn(II), Co(II), Ni(II) and Cu(II) homoleptic complexes with 6-chloro-5-7-dimethyl-4oxo-4H-chromene-3-carbaldehydes and its heteroleptic complexes with quinoline-8 ol: synthesis,characterization and antimicrobial activity

Research on Chemical Intermediates - In the present study, the synthesis of ligand 6-chloro-5-7-dimethyl-4oxo-4H-chromene-3-carbaldehydes by three steps from the substituted phenol. The formed...     

Hydrogenation of olefins on Ru/pillared montmorillonite

Hydrogenation reactions of olefinic hydrocarbons using ruthenium-incorporated pillared montmorillonite as catalysts are reported. Depending on the steric hindrance, Ru/pillared montmorillonite selectively reduces carbon-carbon double bonds using hydrogen under pressure.     

Synthesis of embellished bicyclo[2.2.2]octenones and a sigmatropic 1,2-acyl shift in an excited state: a novel and stereoselective route to (±)-hirsutic acid C and complicatic acid

Formal syntheses of hirsutic acid C and complicatic acid via cycloaddition of cyclohexa-2,4-dienone with methyl methacrylate and a triplet sensitized 1,2-acyl shift are described. The X-ray crystal structure of one of the key intermediates is also reported.     

Apparent and Transfer Molar Volumes for Aqueous Solution Containing Polyethylene Glycols and Amino Acid Ionic Liquids at 298.15 K

The densities of 1-n-butyl-3-methylimidazolium ([Bmim]) based amino acid ionic liquids (AAILs) prepared from glycine [Gly], alanine [Ala], and valine [Val], namely [Bmim][Gly], [Bmim][Ala] and [Bmim][Val], in aqueous?~?0.2 mol·kg^?1 polyethylene glycol (PEG400, PEG600 or PEG1000) and PEG400 solutions containing?~?(0.0946, 0.1891 and 0.3820) mol·kg^?1 of [Bmim][Gly], have been determined at 298.15 K. The experimental densities were used to evaluate the apparent molar volumes in the mixed solvent system and further used to obtain transfer molar volumes of AAILs for their transfer from water to aqueous PEG solutions and of PEG400 for its transfer from water to aqueous solutions containing (0.0946, 0.1891 and 0.3820) mol·kg^?1 of [Bmim][Gly]. The transfer molar volumes of AAILs and of PEG400 are found to be negative. The effects of alkyl chain-length variation on the anion of AAILs as well as the chain-length of PEG on transfer molar volumes are investigated and discussed in terms of hydrophobic–hydrophilic, hydrophobic–hydrophobic, and ion–hydrophobic interactions.