570 



CHEMISTRY OF THE PROTEIDS 



CHAP. 



an elastin if judged by its composition and its properties, but is 

 almost as insoluble as is keratin, and has therefore been called kerato- 

 elastin by Neumeister. 



Ordinary elastin is not much more soluble than is keratin ; it is 

 not attacked by 5 per cent KOH in the cold, and hardly by hot 1 per 

 cent KOH. It is, however, digested by both pepsin + hydrochloric 

 acid and by trypsin, and is converted, although slowly, into albumoses. 

 To obtain it in a pure form, the other constituents with which it occurs 

 together are removed by alternate treatment with acids and alkalies. 



Chittenden and Hart 1 found the percentage -composition of the 

 elastin of the ligamentum nuchse of the ox to be : 



054-08 H7-2 N 16-85 S 0-3. 



The analysis of Horbaczewski ^ and Zoja 3 for the same elastin, and 

 those of Schwarz 4 and Bergh 5 for the aorta-elastin, agree well with 

 one another, for all give a high carbon and a low sulphur per- 

 centage. All observers agree in finding large amounts of leucin (see 

 below). Horbaczewski found 0'7 per cent ammonia, 0'25 per cent 

 tyrosin, glycocoll, and amino-valerianic acid; Schwarz obtained 0*34 

 per cent tyrosin, and Kossel and Kutscher 0*3 per cent arginin. The 

 latest analysis by Abderhalden and Schittenhelm 6 gives for 400 

 grammes of elastin these figures : 



Elastin is amongst all albuminous substances the one poorest in 

 tyrosin and arginin. The indol-derivatives are completely absent on 

 subjecting elastin to bacterial digestion, according to Walchli 7 and 

 Zoja. 8 Engel 9 found that elastin, which had been rendered soluble 



1 R. H. Chittenden and A. S. Hart, Zeitschr.f. Biol. 25. 368 (1889). 



2 J. Horbaczewski, Zeitschr. f. physiol. Chem. 6. 330 (1882) ; Monatsh. f. Chem. Q. 

 639 (1885). - 3 L. Zoja, Zeitschr. f. physiol. Chem. 23. 236 (1897). 



4 H. Schwarz, ibid. 18. 487 (1893). 



5 Ebbe Bergh, ibid. 25. 337 (1898). 



6 Abderhalden and Schittenhelm, ibid. 41. 293 (1904). 



7 G. Walchli, Journ. f. prakt. Chem. [2] 17. 71 (1878). 



8 L. Zoja,' Zeitschr.f. physiol. Chem. 23. 236^(1897). 



9 W. Engel, Zeitschr. /. Biol. 27. 374 (1897). 



