Search results for "Amide"
showing 10 items of 3119 documents
Approaches to estimate the time and height at the peak maximum in liquid chromatography based on a modified Gaussian model
2011
The time and height at the peak maximum are key parameters to describe a chromatographic peak with prediction or optimization purposes, or in the qualitative/quantitative analysis of samples. Three different approaches to estimate these parameters, using the experimental points in the peak maximum region, are here described and compared. The approaches are based on the reliable description of the peak profile using a modified Gaussian model with a parabolic variance (PVMG). In the first approach, non-linear fitting of the chromatographic data to the PVMG model is carried out to obtain the time and height at the peak maximum (Approach I). In the other two approaches, the PVMG model is linear…
An automatic multidimensional chromatography system for purification of human uterine progesterone receptor and induction of polyclonal antibodies.
1986
Abstract This paper reports on the synthesis of Org2058-bonded microparticulate silicas and their use in affinity chromatography as the first step for the purification of human progesterone receptor. The development of microprocessor-controlled instruments allows all the various steps to be performed automatically. The various steps used for the purification of human progesterone receptor were carried out with the FPLC system: (1) affinity chromatography, (2) desalting of eluate on Sephadex G-25, (3) anion-exchange chromatography using a Mono Q column. With this procedure the receptor was purified approx. 10,000-fold within 24 h. The yield of receptor was generally 85–95%. Investigations wi…
Performance of a series of novel N-substituted acrylamides in capillary electrophoresis of DNA fragments
1996
DNA separations by capillary electrophoresis in viscous solutions of novel polymers, made with Ω-hydroxyl, N-substituted acrylamides (notably N-acryloyl amino propanol, AAP and N-acryloyl amino butanol, AAB) are evaluated. Whereas in standard poly(acrylamide), at 6% concentration, the theoretical plate number (N) does not exceed 500 000, in 6% poly(AAP) N reaches 922 000 and in 6% poly(AAB) N values as high as 1 200 000 are obtained. Also, copolymers of AAP and AAB give N values in excess of 1 million plates. The two novel monomers (AAP and AAB) remain extremely stable during alkaline hydrolysis and display very good hydrophilicity, while being devoid of the noxious habit of auto-polymeriza…
An automated on-line multidimensional HPLC system for protein and peptide mapping with integrated sample preparation.
2002
A comprehensive on-line two-dimensional 2D-HPLC system with integrated sample preparation was developed for the analysis of proteins and peptides with a molecular weight below 20 kDa. The system setup provided fast separations and high resolving power and is considered to be a complementary technique to 2D gel electrophoresis in proteomics. The on-line system reproducibly resolved approximately 1000 peaks within the total analysis time of 96 min and avoided sample losses by off-line sample handling. The low-molecular-weight target analytes were separated from the matrix using novel silica-based restricted access materials (RAM) with ion exchange functionalities. The size-selective sample fr…
Membrane Protein Subunit Fractionation by Means of Inverse Pore Gradient Elution Polyacrylamide Gel Electrophoresis
1996
We report here the preparative scale isolation of the four subunits of the nicotinic acetylcholine receptor (nAChR) applying short inverse pore gradient SDS gels on an elution-PAGE apparatus. The nAChR subunits are of similar molecular weights (alpha, 50.2 kDa; beta, 53.7 kDa; gamma, 56.3 kDa; delta, 57.6 kDa) and isoelectric point (approx 5.5) and share the typical properties of amphiphatic membrane proteins that are difficult to separate by chromatographic procedures. Preparative PAGE, which has proved to be the method of choice for nAChR-subunit fractionation, however, is time-consuming and achieves only moderate resolutions yielding dilute fractions. We present here the fractionation of…
Ionomers in solution: 1. Viscometric and chromatographic studies in cononsolvent and cosolvent mixtures
1997
Abstract The viscosity and elution behaviour of polystyrene sulfonate ionomers with varying ionic content has been studied in the pure solvents chloroform (CHL), tetrahydrofuran (THF), dioxan (DIO), ethyl acetate (EA) and dimethylformamide (DMF) as well as in their cononsolvent mixtures CHL/THF (50:50), DIO/CHL (75:25) and in the cosolvent mixture EA/DMF (50:50). In the pure solvents with low dielectric constant the reduced viscosities of ionomers are lower at low concentrations and higher at moderate ones than the respective viscosities of the polystyrene precursor. These results can be explained by formation of intramolecular and intermolecular associations. Moreover, differences in visco…
Preferential solvation of a dicyanate ester monomer and poly(sulfone) in different organic solvents by size-exclusion chromatography.
2002
Preferential solvation parameters A in the ternary systems solvent (1) -monomer (2) -polymer (3) were determined as a tool to measure the compatibility between the cyanate ester monomer Arocy B10 and poly(sulfone), PSF, in the presence of three organic solvents: tetrahydrofuran, dimethylformamide and dicloromethane. The A parameter was measured by size-exclusion chromatography at different monomer-to-polymer ratios. The quantitative evaluation was rigorously made at polymer-diluted conditions. PSF was found to be preferentially solvated by the monomer. Concerning the solvent used, systems containing tetrahydrofuran showed the strongest solvation, the lowest A values being those obtained in …
Purification and Characterization of <I>Bacillus cereus</I> Protease Suitable for Detergent Industry
2005
An extracellular alkaline protease from an alkalophilic bacterium, Bacillus cereus, was produced in a large amount by the method of extractive fermentation. The protease is thermostable, pH tolerant, and compatible with commercial laundry detergents. The protease purified and characterized in this study was found to be superior to endogenous protease already present in commercial laundry detergents. The enzyme was purified to homogeneity by ammonium sulfate precipitation, concentration by ultrafiltration, anion-exchange chromatography, and gel filtration. The purified enzyme had a specific activity of 3256.05 U/mg and was found to be a monomeric protein with a molecular mass of 28 and 31 kD…
Use of an enzyme-assisted method to improve protein extraction from olive leaves.
2013
The improvement of protein extraction from olive leaves using an enzyme-assisted protocol has been investigated. Using a cellulase enzyme (Celluclast® 1.5L), different parameters that affect the extraction process, such as the influence and amount of organic solvent, enzyme amount, pH and extraction temperature and time, were optimised. The influence of these factors was examined using the standard Bradford assay and the extracted proteins were characterised by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum extraction parameters were: 30% acetonitrile, 5% (v/v) Celluclast® 1.5L at pH 5.0 and 55°C for 15min. Under these conditions, several protein extracts…
Influence of sodium lauryl sulphate on the in vitro percutaneous absorption of compounds with different lipophilicity
1997
Abstract The effects of sodium lauryl sulphate (SLS) at different concentrations on the “in vitro” percutaneous absorption of a number of compounds (5-fluorouracil, antipyrine, pentoxifylline, salicylamide, 4-ethylaniline, 4-n-butylaniline and indomethacin) with a wide range of lipophilicity values (log POCT from −0.95 to 4.42) through rat skin were analysed. After pretreatment of the skin with SLS (1% and 5%, w/w) the permeability coefficients increased only for compounds having a log POCT