CHAPTER IV 



THE CONSTITUTION OF ALBUMINS 



(See also pp. 237-249) 



The Linking* of Amino- acids 



SCHUTZENBERGER l advanced, in 1875, the view that albumins ought 

 to be considered as derivatives of urea, NH 2 CO NH 2 and of 

 oxamid, NH 2 CO CO NH 2 , but this would only account for the 

 guanidin-remainder, CNH . NH 2 , occurring normally in arginin. 2 

 The conception of Nasse, 3 that albumins are built up as esters, con- 

 taining the grouping : = C C = , will also only account for a 

 small percentage of the total amount of albumin, for radicals con- 

 taining the alcohol-group OH are tut few, such as serin, tyrosin, 

 oxyprolin, and the diamino-oxycarboxylic acids, mentioned on pp. 44, 

 45. For these reasons Hofmeister 4 advanced in 1892 the theory that 

 albumins are linked up according to the general formula : -CH 2 NH 

 CO or NH CH 2 CO NH. He based his view partly on 

 the fact that this grouping occurs in arginin and in leucin-imide : 



C 4 H 9 



CH 



CH 2 .NH.C(NH).NH 2 , , 



(CH 2 ) 2 



CH.NH 2 COSH- 



CO. OH \/ 



CH 



CA 



Arginin. Leucinimide. 



and partly on the fact that according to Low 5 and Schiff, 6 relatively 



1 Schiitzenberger, 'tfber d. Proteinkorper,' Ohem. CentrcUbL, 1875, 1876. 



2 That oxamide occurs normally is held by Kutscher and Schenk, see p. 244. 



3 0. Nasse, " fiber d. Wirkung der Fermente," Rostocker Zeitung, 15th Dec. 1894. 



4 F. Hofmeister, Ergebnisse d. Physiologie, 1. i., p. 159 (1902). 



5 0. Low, Journ. f. prakt. Chem. 31. 129. 



6 H. Schiff, Ber. d. deutsch. chem. Ges. 29. 1354. 



139 



