Méthode de marquage de groupes carboxyliques dans les peptides. Propriétés chromatographiques et autres,de peptide-p,p′-dimapa-anilides

Résumé Les auteurs décrivent une méthode efficate et les conditions (faibles valeurs de pH, milieu dioxane/eau (1∶2), carbodiimide hydrosoluble) de formation de peptides colorés par réaction de leur groupe carboxylique avec un colorant aminé (par exemple: 1(4-diméthylamino-1 phénylazo)-4-aminobenzène=p,p′-dimapa-aniline), sans polymérisation du peptide non-protégé. Quelques méthodes chromatographiques, faciles à mettre en oeuvre, pour l'isolement de peptide-p,p′-dimapa-anilides et quelques propriétés de ces nouveaux composés (peptides-C-colorés) sont présentées.

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Method for labelling carboxylic groups in peptides. Chromatographic and other properties of peptide-p,p′-dimapa-anilides

Summary The authors describe an effective method and the conditions (low pH values, dioxane/water (1∶2) media, watersoluble carbodiimide) for making coloured carboxylic peptides from amino-dye (i.e.: 1(4-dimethylamino-1 phenylazo)-4-aminobenzene=p,p′-dimapa-aniline), without polymerisation of unprotected peptide. Some easy chromatographic methods for isolation of peptide-p,p′-dimapa-anilides and some properties of these new compounds (C-dyed-peptides) are given.

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Electrode reaction of zinc ions at a dropping mercury electrode in ammonium sulphate solutions

The electrode reaction of Zn(II) at a DME in aqueous solutions of (NH₄)₂SO₄ has been studied by d.c. and square-wave polarography at 25.0±0.1°C. The electrochemical kinetic parameters for the reaction are determined. The appearance of the second wave in the square-wave polarogram has been attributed to the low values of the rate parameter and the transfer coefficient.     

The crystal and molecular structure of 12,13-dibromopseurotin.

The crystal structure of 12,13-dibromopseurotin has been determined by single crystal X-ray analysis. The crystals belong to space group P2₁ with a = 16.75, b = 9.63, c = 7.42 Å, β 95.9°, Z = 2. The structure was solved by the heavy atom technique and refined to R = 0.062 with 819 significant reflexions for 299 parameters.     

Caesium as counter-ion in the anionic polymerization of ethylene oxide—II: Kinetics in hmpt

Results are reported for the kinetics of the anionic polymerization of ethylene oxide in hexamethylphosphoramide using the caesium alkoxide of the monoethylether of diethylene glycol as initiator at 40·0°.The reactions were found to be first order in monomer and 0·5 in initiator; rates are depressed by adding caesium tetraphenyl boride. These results indicate that propagation takes place by free ions and ion pairs; the respective propagation rate constants are k_(?) = 22 and k_(±) = 0·2 M 'sec.     

The collection and determination of atmospheric gaseous bromine and iodine

A procedure has been developed which allows for the isolation, collection and analysis of atmospheric gaseous iodine and bromine. Particulate matter is removed from the airstream to be sampled by electrostatic precipitation. The gaseous halogen species are adsorbed onto specially cleaned activated charcoal. After irradiation of the charcoal sample with thermal neutrons, the iodine and bromine are removed from the charcoal, isolated, and purified as the AgX precipitate. The amounts of gaseous iodine and bromine are then determined by β-counting. The system works well for air sheds with low particulate iodine and bromine concentrations relative to that in the gaseous phase. In air sheds where the particulate halogen predominates, the gas phase measurements are more uncertain.     

Assay of flurazepam in plasma by differential pulse polarography

Analytical and Bioanalytical Chemistry - A combination of differential solvent extraction based on physical chemical properties of the species involved and differential pulse polarography has been...