20 CHEMISTRY OF THE PROTEIDS CHAP. 



A great advance was made when Drechsel l discovered that, in 

 addition to mono-amino-acids, there occur also basic compounds amongst 

 the dissociation-products of albumins. He found lysin, a diamino- 

 caproic acid, and lysatinin. From the latter Hedin 2 prepared arginin, 

 which E. Schulze 3 had previously already discovered in germinating 

 lupine. Kossel 4 added to the two bases lysin and arginin a third one, 

 namely, histidin, the constitution of which has recently been fully 

 cleared up (see p, 41). 



Lysin, arginin, and histidin Kossel 5 calls the three hexone bases. 

 These substances formed, and still form, the centre of interest, 

 especially since Kossel 6 succeeded in working out methods for their 

 quantitative estimation, and so made it possible to determine, in a 

 systematic manner, the relative amounts in which they occur in 

 different albumins. Arginin is present in every albumin ; 7 lysin and 

 histidin are only absent in some of the protamins, and lysin also in 

 some vegetable albumins. (See Tables on pp. 70-75, and also 

 p. 65.) 



Of very great importance also is the discovery by Skraup of the 

 diamino-polycarboxylic acids (see p. 44), as these represent the connect- 

 ing link between the amino-acids and the sugars. 8 



Through E. Fischer 9 interesting himself in the mono-amino-acids,. 



1 E. Drechsel, Arch. f. (Anat. u.) Physiol. 1891, p. 248 ; Ber. der Sachs. Ges. d. 

 Wiss. 1889, 1890. 

 X 2 S. G. Hedin, Zeitschr. f. physiol. CJiem. 21. 155 and 297 (1895). 



3 E. SchulzeV^d 11. 43 (1886) ; Ber. d. deutsch. chem. Ges. 19. I, 1177 (1886). 

 ^ 4 A. Kossel, Zeitschr. f. physiol. Chem. 22. 176 (1896). 



5 A. Kossel, Deutsclie med. Wochenschr. 1898, S. 581. 

 ^ 6 A. Kossel and Fr. Kutscher, Zeitschr. f. physiol. Chem. 31. 165 (1900). 



7 A. Kossel, Ber. d. deutsch. chem. Ges. 34. III. 3214 (1901). 



8 C. Neuberg, Syuthese von "Oxy- and Diamino-sauren, " Zeit.f. physiol. Chem. 45- 

 92 (1905). 



9 E. Fischer, 'Dissociation of Racemic Amino - Acids, ' Ber. d. deutsch. chem. Ges. 

 32. II. 2451 and 3638 (1899) ; E. Fischer, ibid. 33. II. 2370 (1900) ; E. Fischer and 

 A. Mouneyrat, ibid. 33. II. 2383 (1900) ; E. Fischer and R. Hagenbach, ibid. 34. 

 III. 3764 (1901); E. Fischer, 'Esters of Amino -Acids,' ibid. 34. I. 433 (1901); 

 'Synthesis of a-5-Diamino-valerianic Acid,' 34. I. 454 (1901) ; 'Synthesis of a-7-Dia- 

 mino-butyric Acid,' 34. II. 2900 (1901) ; ' Synthesis of a-e-Diamino-caproic Acid,' 35. 

 III. 3772 (1902) ; E. Fischer, 'Hydrolysis of Casein by means of Hydrochloric Acid,' 

 Zeitschr. f. physiol. Chem, 33.^151 (1901) ; E. Fischer and A. Skita, 'Fibroin of Silk,' 

 ibid. 33^177 (1901) ; E. Fischer, ' Phenylalanin and a-Pyrrolidin-Carboxylic Acid from 

 Egg Albumin,' ibid. 33y412 (1901) ; E. Fischer, P. A. Levene, and R. H. Aders, 

 'Hydrolysis of Gelatine,' ibid. 35.^70 (1902); E. Fischer and A. Skita, 'Fibroin and 

 Gelatine of Silk' ibid. 35. 221 ""(1902) ; E. Fischer, 'Formation of a-Pyrrolidin- 

 Carboxylic Acid during Hydrolysis of Casein by means of Alkali,' ibid. 35. 227 (1902) ; 

 E. Fischer, ' Quantitative Determination of Glycocoll,' ibid. 35/229 (1902) ; E. Fischer 

 and E. Abderhalden, ' Oxyhamioglobin,' ibid?36. 268 (1902) ; E. Fischer and T. Dor- 

 pinghaus, 'Hydrolysis of Horn.' ibid. 36. v 462 (1902) ; E. Fischer, ' Oxy-ct-Pyrrolidin- 



