THE AMIDE NITROGEN OF PROTEIDS.* 



BY YANDELL HENDERSON. 



THE fact that, on decomposition with strong hydrochloric 

 acid, a part of the nitrogen of the proteid molecule is obtained 

 as ammonia was first revealed by Hlasiwetz and Habermann f 

 in their now classic investigations on the cleavage products of 

 the proteids. Following them, Nasse $ carried out a series 

 of quantitative determinations as to the percentage of the 

 nitrogen thus separated, and found marked differences between 

 the different albuminous bodies in their content of this 

 " loosely combined nitrogen." More recently these investiga- 

 tions have been repeated by Hausmann, and also considerably 

 widened in scope by quantitative analyses, not only of this 

 " amide " nitrogen, but also of the " diamino " and " mono- 

 amino " nitrogen || obtained by decomposing proteids with 

 strong hydrochloric acid. 



The results so obtained have led Hausmann to regard the 



* These investigations were first published under the title, Zur Eenntniss 

 des durch Sauren abspaltbaren Stickstoffes der Eiweisskorper, in Zeitschr. f. 

 physiolog. Chemie, Band xxix, Seite 47. 



The experiments here recorded were completed before the publication of 

 Hausmann's work. More recently Hausmann has published a second paper 

 in support of his views, and Kutscher has put forward a criticism of them 

 supported by considerable experimental data. These articles are : W. Haus- 

 mann, Zeitschr. f. physiolog. Chemie, Band xxix, p. 186 ; FT. Kutscher, 

 Zeitschr. f. physiolog. Chemie, Band xxxi, p. 215. 



t Hlasiwetz und Habermann, Ueber die Proteinstoffe, laebig's Annalen, 

 Band 169, neue Reihe 93, pp. 150-166. 



t Otto Nasse, Studien iiber die Eiweisskorper, Pfliiger's Archiv, Band vii, 

 pp. 139-158. 



W. Hausmann, Ueber die Vertheilung des Stickstoffes im Eiweissmolekiil, 

 Zeitschr. f . physiolog. Chemie, Band xxvii, p. 95. 



|| Hausmann designates as " amide " nitrogen the " loosely combined nitro- 

 gen" of Nasse. Monoamino nitrogen is that contained in the amido acids 

 leucin, tyrosin, glutamic acid, etc., and diamino nitrogen that of the bases 

 precipitated by phosphotungstic acid. 



