Reagent

About: Reagent is a research topic. Over the lifetime, 60091 publications have been published within this topic receiving 1234928 citations. The topic is also known as: reagens.

Efficient ring-opening reaction of epoxides and aziridines promoted by tributylphosphine in water.

Abstract: Tributylphosphine was found to be an effective promoting reagent for the ring-opening reaction of various epoxides and aziridines with nucleophile to produce corresponding anti-bifunctional products in moderate to excellent yields in water.

[34] Modification of tryptophan with BNPS-skatole (2-(2-nitrophenylsulfenyl)-3-methyl-3-bromoindolenine).

Abstract: Publisher Summary Reaction with (2-(2-Nitrophenylsulfenyl)-S-methyl-3-bromoindolenine) BNPS-skatole and subsequent reduction of the 4 partially oxidized methionine residues produced a derivative of nuclease with modification only of residue 140, a single tryptophan. BNPS-skatole is poorly soluble in water. The stability of nuclease in aqueous acetic acid permitted use of such acidic solvent conditions. If other proteins require a neutral pH range, the reagent may be dissolved in an organic solvent and then added to the protein solution. As with nuclease, reversibly denaturing conditions of pH or of added urea or guanidine may be required to expose the tryptophan residues to reagent. The important feature of BNPS-skatole as a modifying reagent for tryptophan residues lies in its higher selectivity in comparison to N-Bromosuccinimide (NBS). BNPS-skatole rapidly achieves quantitative oxidation of the indole ring of tryptophan and the sulfur atom of methionine. The use of BNPS-skatole for the selective cleavage of the tryptophanyl peptide bond might prove useful in sequence studies.

Study of carbon, hydrogen and nitrogen determination by combustion-gas chromatography

Abstract: The method for carbon-hydrogen-nitrogen determination based on dynamic rapid combustion of the sample, gas chromatographic separation and thermal-conductivity measurement of the gases N2, CO2 and H2O is critically considered and improved. In order to achieve instantaneous combustion of all types of organic compounds, oxidizable metallic containers are used for the sample and dropped in the hot combustion zone while the carrier gas is momentarily enriched with pure oxygen. Flash combustion of the sample is followed by catalytic oxidation on a newly developed active catalyst. This reagent, adsorption-free and thermally resistent, consists of pure chromic oxide, mechanically compressed and granulated. Copper treated with silver is used as reducing reagent. Unwanted gases are eliminated with Co3O4 containing silver, and by utilizing the chemiadsorption properties of the column packing. Measurements are made by integrating and printing the electrical signal. The analytical process is controlled by means of a potentiometric recorder. The increased combustion capacity, the practical absence of blanks and the very extended linearity of response of the detector make possible CHN determination in sample sizes of 0.1–3 mg. Except for sample weighing and calculation of results from the printed integration values, all the operations are automatically controlled by a preset programme.

Polyethylenimine, a cost-effective transfection reagent

Abstract: In search for a cheap and effective transfection reagent we used the positively charged polyplex-forming compound polyethylenimine (PEI). This compound is commercially available from different companies either as a non-modified chemical reagent or with additives as a more cost intensive transfection reagent. Here we used the non-modified PEI reagent to optimize transfection protocols for different cell-lines. With these optimized conditions we were able to transiently transfect a number of cell-lines up to 40–90%.