146 



THE PROTEINS AND THE AMINO-ACIDS 



stated to be a quantitative measure of the tryptophane-content of the 

 protein. 



The following are representative results obtained by Van Slyke's 

 method. 



PERCENTAGE OF THE TOTAL NITROGEN CONTAINED IN VARIOUS AMINO- 

 ACID GROUPS OF THE UNDERMENTIONED PROTEINS. 



The following are among the estimations of. the amino-acids yielded 

 by various proteins, estimated by the more exhaustive but less con- 

 venient method of Emil Fisher. 1 It must be recollected, however, 

 that the estimates for the majority of the monamino-acids are minimal 

 estimates only, for the reason that in the process of analysis a certain 

 proportion of the nitrogen escapes estimation. It is probable, however, 

 that in experienced hands the losses are of similar magnitude and kind 

 so that the results obtained by different investigators may be con- 

 sidered comparable. From these figures it may clearly be seen how 

 variable is the composition of different proteins in respect to their 



1 Cited from analyses reported by: 



Osborne, T. B., and Mendell, L. B.: Jour. Biol. Chem., 1914, 17, p. 336. 



Osborne, T. B., and Jones: Am. Jour. Physiol., 1910, 26, p. 305. 



Kossel: Zeit. fur Physiol. Chem., 1905, 44, p. 347. 



Osborne and Guest: Jour. Biol. Chem., 1911, 9, p. 425. 



Osborne and Clapp: Am. Jour. Physiol., 1906-7, 17, p. 231. 



Osborne, Van Slyke, Leavenworth and Vinograd: Jour. Biol. Chem., 1915, 22, 



p. 259. 



Abderhalden, E.: Zeit. Physiol. Chem., 1902-3, 37, p. 499. 

 Abderhalden, E.: Zeit. Physiol. Chem., 1903-4, 40, p. 249. 

 Kossel, A., and Patten, A. J.: Zeit. Physiol. Chem., 1903, 38, p. 39. 

 Fischer, E.: Zeit. Physiol. Chem., 1903, 39, p. 155. 

 Morner: Ibid., 1901-2, 34, p. 207. 



Osborne and Guest: Jour. Biol. Chem., 1911, 9, p. 333. 

 Abderhalden and Pribram: Zeit. Physiol. Chem., 1907, 51, p. 409. 

 Fischer and Bolhner: Zeit. Physiol. Chem., 1910, 65, p. 118. 

 Fischer, Levene and Aders: Zeit. Physiol. Chem., 1902, 35, p. 70. 

 Skraup and Biehler: Monatsh. f. Chem., 1909, 30, p. 467. 

 Levene and Beatty: Zeit. Physiol. Chem., 1906, 49, p. 252. 

 Taylor, A. E.: Jour. Biol. Chem., 1908-9, 5, p. 389. 

 Osborne and Jones: Am. Jour. Physiol., 1909, 24, p. 437. 



