Study of the separation of mouse monoclonal antibodies by pseudobioaffinity chromatography using matrix-linked histidine and histamine.

The selective retention of proteins on matrix-linked histidine has been shown to depend on chromatographic conditions: pH, temperature and ionic strength. An extension of this study to separate mouse monoclonal antibodies on histidyl-Sepharose is presented here; the roles of different functional groups such as imidazole, primary amine and carboxyl groups are elucidated by using histamine-Sepharose and histidine linked via the carboxyl group of the alpha-amino acid. We separated two monoclonal antibodies, immunoglobulin G1 (IgG1) from a culture supernatant and IgG2b from ascites fluid precipitated with 50% ammonium sulphate. The pseudoselective retention of monoclonal IgG1 on the three different matrices and IgG2b on histidyl-aminohexyl-Sepharose was achieved at pH 7.4. The purity of the final monoclonal antibody preparation determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis under reducing conditions proved the separation of the monoclonal antibodies (IgG1, IgG2b) from other contaminating proteins such as albumin and transferrin. Quantitation of the mouse monoclonal antibodies was carried out using enzyme-linked immunosorbent assay.     

Investigations on the preparation,oxidation and reduction reactions of thiophosphoryl fluoride

Pure thiophosphoryl fluoride has been prepared by the fluorination of thiophosphoryl chloride by sodium fluoride in acetonitrile medium. Oxidation of this phosphoryl fluoride by acidified chloramine-T ruptures the phosphorus-sulphur bond and oxidises the sulphur present to the hexavalent state. Anhydrous hydrogen iodide reduces the sulphur to hydrogen sulphide and phosphorus to the trivalent state.     

Thermal Decomposition of Strontium Iron Citrate

The citrate precursor method has been used to synthesise ultrafine SrFe₁₂O¹⁹. The thermal decomposition of citrate precursor SrFe₁₂O₆ (C₆H₆O₇)₁₃ was investigated by TG, DTG and DTA techniques, gas and chemical analyses. The citrate precursor on decomposition in static air atmosphere yields pure and stoichiometric SrFe₁₂O₁₉. The decomposition consists of three major steps, the formation of acetone dicarboxylate complex occurs around 165°C. The citrate groups are completely destroyed in the temperature range 195–315°C resulting in the formation of complex carbonate with the evolution of acetone and CO₂ gas. The decomposition of carbonate results in the formation of ultrafine SrFe₁₂O₁₉ below 550°C with the evolution of CO₂ gas. The ultrafine particles are observed as platelet clusters having crystallite size 13 nm and surface area 76.4 m² g^?1. The citrate precursor and the decomposed products were characterised by IR, NMR, XRD, SEM and surface area measurements.     

A phase-matchable nonlinear optical crystal 4-amino-5-mercapto-3-[1-(4-isobutylphenyl)ethyl]-1,2,4-triazole: Synthesis,crystal growth and characterization

In this paper, we report the synthesis, growth and characterization of a new organic NLO single crystal of 4-amino-5-mercapto-3-[1-(4-isobutylphenyl)ethyl]-1,2,4-triazole (AMIT). The title compound is synthesized and single crystals were grown by the slow evaporation technique at room temperature. The grown crystal was characterized by powder XRD, FTIR, UV-Vis. and microhardness studies. The thermal analysis of the crystal was carried out by TGA, DTAand DSC. FromDSC, the melting point of the crystal is found to be 168°C. The scanning electron microscopy (SEM) provides information about the surface morphology of the crystal. The SHG efficiency has been estimated as 0.3 times that of KDP using Kurtz powder method and is found to be a phase-matchable NLO crystal.     

Intensity clamping and re-focusing of intense femtosecond laser pulses in nitrogen molecular gas

We present results of measurements of fluorescence spectra due to the interaction of a Ti:sapphire laser pulse with N₂ molecules at different gas pressures and pulse energies. The analysis of the data together with the results of numerical simulations, using a propagation model, reveal signatures of the phenomena of intensity clamping and of re-focusing of the laser pulse at high gas pressure. The laser pulse energy for intensity clamping as a function of the gas pressure is determined. Received: 21 May 2001 / Revised version: 10 July 2001 / Published online: 19 September 2001     

Piperidinium 3‐[(4‐hydroxy‐5,7‐di­methyl‐2‐oxo‐2H‐chromen‐3‐yl)­phenyl­methyl]‐5,7‐di­methyl‐2‐oxo‐2H‐chromen‐4‐olate

In the title salt, C₅H₁₂N⁺·C₂₉H₂₃O₆^?, both benzo­pyran systems are planar. Intermolecular N—H?O hydrogen bonds and a short O—H?O intramolecular hydrogen bond are observed in the structure.     

Investigations on the multiply charged nuclei of the primary cosmic radiation near the geomagnetic equator using nuclear emulsions

The interaction mean-free paths and fragmentation parameters associated with collisions of nuclei of Z?6 and E?7·5 Gev/n have been measured using emulsion-graphite sandwich stacks exposed to the primary cosmic radiation at Hyderabad, India (Geomagnetic latitudeλ=7·6° N). The results are based on a total of 213 nuclear interactions observed in graphite. Since the atomic number of graphite is very close to the mean atomic number of air, the parameters derived for graphite medium are directly applicable to air. A comparative study has been made of the results thus obtained with similar data available for nuclei of E?1·5 Gev/n.     

Chromatography of human plasma on aminohexyl Sepharose: separation of factor VIII/vWf and behaviour of factors II, VII, IX and X and antithrombin III

Human plasma was chromatographed under different experimental conditions on aminohexyl Sepharose. A strong retention of factor VIII/vWf and of factors VII, II, IX and X was observed. A satisfactory stabilization of eluted factor VIII clotting activity was obtained after addition of albumin and sucrose to the buffers used during chromatography. Albumin and antithrombin III were found apparently intact in the column effluent.     

Crystal and molecular structure ofl-3-(2-acetamido-2-ethoxycarbonyl)ethylindole

l-3-(2-Acetamido-2-ethoxycarbonyl)ethylindole is monoclinic:a = 11.469(8),b = 8.088(6),c = 8.457(6) Å, = 106.45(7) °,Z = 2,P2₁. The structure has been solved by direct methods with CuK three-dimensional photographic data, and refined by full-matrix least squares toR = 0.097 for 1390 observed reflections. The structure is stabilized by intermolecular N-H...O hydrogen bonds. The indole ring of the molecule is planar within experimental error.Contribution No. 440 from the Department of Crystallography and Biophysics, University of Madras, Guindy Campus Madras-600025, India.     

Studies in molecular structure,symmetry and conformation VII. Crystal structure of 4,4′-diaminodiphenylsulphide

The crystal structure of 4,4-diaminodiphenylsulphide, C₁₂H₁₂N₂S, has been determined by three-dimensional X-ray methods. The crystals are orthorhombic, with space-groupP2₁2₁2₁,a = 9·874(6),b = 19·445(9),c = 5·876(6) andZ= 4. The structure was solved by the heavy-atom method and refined by full-matrix least squares to anR value of 0·074. The molecules are held together by hydrogen bonds of the N-H N type, and form chains parallel to theb axis.Contribution No. 354 from the Centre of Advanced Study in Physics, University of Madras-600025, India.