Search results for "Ion chromatography"
showing 10 items of 314 documents
Self-assembly properties of the proteinaceous coat secreted by the ?slime? variant of Neurospora crassa
1989
The proteinaceous extracellular material (PEM) synthesized by the cells of the ‘slime” strain of Neurospora crassa (see Martinez et al. 1989) was solubilized by treatment with urea or guanidine. Removal of these chemicals by dialysis, caused reassembly of the solubilized proteins into material with the same microscopic appearance as the original PEM. Polypeptide patterns from both native and reassembled structures were identical. Dialysis-mediated reassembly of the solubilized proteins appeared to be dependent on both concentration of the soluble macromolecules and time. Gel chromatography of PEM solubilized with different agents revealed two discrete populations of complexes with molecular…
Solution properties of polyelectrolytes. II. Comparison of the effects of both polyion and eluent salt concentrations on the calibrations in aqueous …
1987
The elution behaviour of charged water-soluble polymers (sodium polystyrene sulphonate) in both salt-free and NaCl-containing aqueous mobile phases has been investigated by size-exclusion chromatography. A comparative analysis has been established between the results as a function of polyion and salt concentrations, which demonstrates that the chromatographic behaviour is similar in both cases. The variation of the slopes of the different concentration-dependent calibration curves is discussed in terms of polyelectrolyte conformational changes. Finally, a semi-empirical model has been developed to predict the dependence of the elution volume in either polyion or salt concentration, and its …
Comparative study for separation of aquatic humic-type organic constituents by DAX-8, PVP and DEAE sorbing solids and tangential ultrafiltration: ele…
2005
Aquatic humic-type solutes were separated in parallel from the same fresh water source by four different procedures: non-ionic polymethyl methacrylate (DAX-8) and functional cross-linked polyvinylpyrrolidone (PVP) resins, functional diethylaminoethyl cellulose (DEAE) and tangential ultrafiltration completed with a weakly basic anion exchange resin (IRA-67). The similarity-dissimilarity between the quantities and qualities of the different humic samples is discussed, especially in the light of the original dissolved organic matter (DOM). During the past two decades, a significant progress has occurred in the aquatic humic research due to the so-called hydrophobic-hydrophilic properties posse…
Advanced CPMAS-13C NMR techniques for molecular characterization of size-separated fractions from a soil humic acid
2006
A humic acid extracted from a volcanic soil was subjected to preparative high-performance size-exclusion chromatography (HPSEC) to reduce its molecular complexity and eleven different size fractions were obtained. Cross-polarization magic-angle spinning 13C NMR (CPMAS 13C NMR) analysis performed with variable contact-time (VCT) pulse sequences showed that the largest molecular-size fractions contained aromatic, alkyl, and carbohydrate-like components. The carbohydrate-like content and the alkyl chain length seemed to decrease with decreasing molecular size. Progressive reduction of aromatic carbon atoms was also observed with decreasing molecular size of the separated fractions. Mathematica…
Über den mechanismus der anionischen polymerisation von acrylnitril mit triphenylphosphin. 7. Mitt. über makrozwitterionen
1972
Die anionische Polymerisation von Acrylnitril mit Triathylphosphin als Initiator in Dimethylformamid wurde bei verschiedenen Temperaturen und unterschiedlichem Verhaltnis der Monomer/Initiator-Konzentrationen untersucht. Erganzt durch spektroskopische Endgruppenbestimmung der Polymeranionen konnte mittels 1H-NMR-Spektroskopie und Gelchromatographie (GPC) sowie emissionsspektralanalytischer Phosphorbestimmung an den rohen und den durch Umfallungen bzw. GPC fraktionierten Polymerproben gezeigt werden, das hier neben einer ubertragung teilweise eine Polymerisation Uber Makrozwitterionen auftritt. Fur die Bildung von Makrozwitterionen, , sind jedoch Mindestwerte des Monomer/Initiator-Verhaltnis…
Beiträge zur polymerisation von 2-isopropenylnaphthalin, 3. Anionische homopolymerisation von 2-isopropenylnaphthalin
1981
The anionic homopolymerization of 2-isoprenylnaphthalene with butyllithium in tetrahydrofuran at –78°C is described. The refractive index increment amounts to dn/dc = 0,2084 ml/g for these polymers in toluene at 25°C and wavelength λ = 436 nm. Determination of the molecular weights by light scattering yielded values between 13 000 and 270 000. The second virial coefficients also determined by light scattering measurements are comparable with the corresponding data of poly(α-methylstyrene). A calibration curve is given for gel permeation chromatography of the poly(2-isoprenylnaphthalene)s, whose polymolecularity indexes Mw/Mn lie between 1,06 and 1,2. Their intrinsic viscosity/molecular weig…
Purification and Characterization of Glutamine Synthetase Isoenzymes from Leaves and Roots of Brassica napus (L.)
1995
Summary The glutamine synthetase enzymes from leaves (GS2) and roots (GSR) of Brassica napus L. have been purified to homogeneity by the application of a three-stage isolation procedure comprising anion-exchange chromatography, adsorption by hydroxylapatite and gel filtration on Sephacryl 5-300 HR. The isoforms of the enzyme show a differential distribution in leaf and root tissues. Elution profiles of hydroxylapatite chromatography showed a distinct behaviour for GS proteins found in leaves and roots. Denaturing SDS-PAGE and Western blot experiments revealed molecular masses of approximately 43.5 and 40.5 kD for GS2 and GSR subunits, respectively. Moreover, kinetic properties determined us…
Calculation of the molecular masses of two newly synthesized thermostable enzymes isolated from thermophilic microorganisms
1995
Two thermostable enzymes synthesized by thermophilic microorganisms were isolated and purified. A thermostable beta-galactosidase was produced in a continuous fermentation process by Bacillus stearothermophilus TP 32 as an intracellular enzyme. After applying different concentration procedures the raw extract enzyme was prepurified on a Sephadex G-200 size exclusion column. The isolated beta-galactosidase fraction was then separated with HPLC on a TSK G 3000 SW size exclusion column to determine the molecular mass based on calibration curves of standard proteins. The other enzyme, a thermostable protease, was synthesized by Bacillus stearothermophilus TP 26 as an extracellular enzyme. After…
Size Exclusion Chromatography of Proteins on Improved Bonded Silica Columns
1985
Publisher Summary This chapter discusses the size exclusion chromatography (SEC) of proteins on improved bonded silica columns. Over the past few years, the use of high performance liquid chromatography (HPLC) has been extended to protein chemistry as a powerful separation and isolation technique. A spectrum of variants providing high resolution potential—ion exchange, reversed phase, hydrophobic interaction, affinity, and size exclusion—is available. Of these, SEC is the simplest with respect to method development and equipment design: proteins are separated according to their size in a short and predictable time span under isocratic conditions. The SEC columns are packed with micro-partic…
Syntheses and properties of gel chromatography materials
1970
Abstract The effect of the mode of synthesis on the characteristics of cross-linked polymers is examined for cross-linked copolymers of ethylvinylbenzene-divinylbenzene and vinyl acetate-divinyl adipate. For homogenously cross-linked gels the amount of cross-linking agent determines the “pore size” of these gels in the swollen state. Decreasing the amount of the divinyl component results in gels with an increase in the excluded molecular weight. The mechanical stability sets the experimental limit of their usage, so this type of gel is mostly suited for the separation of oligomers; polymers, however, may be separated by use of heterogenously cross-linked gels. The latter type of gel is prep…