Volume 190802

The chemical constitution of the proteins / by R. H. Aders Plimmer.

  • Plimmer, Robert Henry Aders, 1877-1955.
Date:
1908
Catalogue details

Licence: Public Domain Mark

Credit: The chemical constitution of the proteins / by R. H. Aders Plimmer. Source: Wellcome Collection.

    24/88 (page 8)
    The Linking Together of Amino Acids. By the action of benzoyl chloride upon the silver salt of glycine, Curtius, in 1881, obtained in addition to the expected hippuric acid C,H,CO.Cl + H,N. CH,. COOH = HCI + C,H,. CO. NH. CH,. COOH two other acids of higher molecular weight. One of these was hippuryl- glycine or benzoyl-glycyl-glycine, C,H;CO. HN ..CH,. CO—NH.CH,. COOH, as was proved by the study of its salts, its ethyl ester and amide, and by its hydrolysis into hippuric acid and glycine. It was the first definite compound known which contained two amino acid residues combined together. The constitution of the other acid, called the y-acid, could not be determined; it had the formula C,,H,,N,O,, was soluble with difficulty in water and gave the biuret reaction. It was formed in larger quantities when hippuric ester was fused with glycine, but under these conditions another compound—benzoyl-bisglycyl-glycine—was formed at the same time, so that in this way a series of compounds resulted, each succeeding member containing a glycyl- NH,. CH,.CO- group more than the pre- ceding one. Further investigations upon the constitution of these compounds were only carried out in 1904 by Curtius and Benrath, who found that the y-acid from the analysis of its silver salt, ester, etc., had the formula C,,H,,N,O,, and that it was benzoyl-pentaglycyl-glycine, C,H, . CO — (NH. CH,. CO), — NH .CH,. COOH, its ester being identical with the compound synthesised by Curtius and Wiustenfeld (see below). Two other compounds—hippuryl-glycine and benzoyl-triglycyl- glycine—were found to be formed by fusing together hippuric ester and glycine, but not the previously isolated benzoyl-diglycyl-glycine. Longer chains than the six membered y-acid are not believed by Curtius and Benrath to be formed in this reaction, In 1890 Curtius, by the action of hydrazine upon benzoyl chloride, benzamide or benzoic ester, obtained benzoylhydrazine, C,H; . COOC,H, + H,N. NH, = C,H,.CO.HN.NH, + HOC,H,, which, when treated with nitrous acid, gave benzoylazoimide, N NN