FRACTIONATION OF THE OXYPROTEIC ACIDS 137 

 OXYPROTEIC ACIDS 



It would seem that the bulk of the "non dose" in the 

 urine, the undetermined nitrogen rest, is to be referred to 

 the group of the oxyproteic acids. These substances have 

 been dealt with in a previous lecture in connection with the 

 subject of the elimination of the residual material of pro- 

 tein metabolism in cancerous affections (Vol. I of this 

 series, pp. 547-551, The Chemistry of the Tissues). The 

 oxyproteic acids, discovered in the urine in 1897 by S. 

 Bondzynski and B. Gottlieb, 52 constitute a group of protein 

 derivatives containing both nitrogen and sulphur, and ap- 

 parently of high molecular structure ; they seem to be char- 

 acterized by an acid nature, the solubility in water and 

 insolubility in alcohol of their baryta salts, and by their 

 precipitation by mercuric acetate in weakly alkaline reac- 

 tion. In general they no longer retain the character of 

 polypeptids, failing to give the biuret reaction, and not being 

 precipitable, as are other protein derivatives of high molec- 

 ular structure, by phosphotungstic acid in the presence of 

 excess of mineral acid. 



Fractionation of the Oxyproteic Acids. The investiga- 

 tions of Bondzynski and his collaborators 53 indicated that 

 separation of these acids is possible by precipitation as salts 

 of the heavy metals, and in fact led to the differentiation of 

 alloxyproteic acid (precipitated by acetate of lead), autoxy- 

 proteic acid (precipitated by mercuric acetate in acid re- 

 actions) and oxyproteic acid (precipitated by the same in 

 neutral or weakly alkaline reaction). These Polish investi- 

 gators are also to be credited with the important determina- 

 tion that the autoxyproteic fraction includes the yellow 



88 S. Bondzynski and R. Gottlieb, Centralbl. f . d. med. Wiss., 1897, No. 33. 



68 S. Bondzynski and K. Panek, Ber. d. deutsch. chem. Ges., 35, 2959, 1903 ; 

 S. Bondzynski. S. Dombrowski, K. Panek, Zeitschr. f. physiol. Chem., 46, 83, 

 1905; S. Dombrowski, ibid., 54, 188, 1907, Bull, de 1'Acad. de Cracovie; Cl. des 

 Sciences Math, et Natur., October, 1907; J. Browinski and S. Dombrowski, 

 Jour, de Physiol., 10, 819, 1908; W. Gawinski, Zeitschr. f. physiol. Chem., 58, 

 458, 1909; S. Bondzynski, Kosmos, 35, 680, 1910. 



