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.     

Reaction of ethyl perfluoromethacrylate with [η5-C5H5Fe(CO)2]− anion

Conclusions The cis-trans isomers of the vinylic fluorine substitution product were isolated and characterized when Na[⁵-C₅H₅Fe(CO)₂] is reacted with ethyl perfluoromethacrylate.Deceased.The authors express their gratitude to E. M. Rokhlin and U. Utebaev for supplying the ethyl perfluoromethacrylate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 705–706, March, 1977.     

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.