244 AMIDO-VALERIANIC ACID. TYROSINE. [BOOK II. 



Amido-valerianic acid, C 5 H n N0 2 

 (C 5 H 9 (NH 2 )0 2 = CH 2 (NH 2 ) - CH 2 - CH 2 - CH 2 - CO . OH). 



This amido-acid was found, on one occasion, in the 

 pancreas of the ox by v. Gorup-Besanez 1 , who afterwards 

 assumed, though doubtless incorrectly, that Nencki's sparingly 

 soluble leucine is amido-valerianic acid 2 . The two bodies have many 

 chemical and physical properties in common, e.g. the compounds 

 they form, their volatility and the sublimate which they yield. 

 Amido-valerianic acid is, however, less soluble in water than leucine, 

 and is optically inactive.* 



It appears probable that ornithin (Jaffe' 3 ), a base excreted in 

 combination with benzoic acid when the latter is administered to 

 hens, is a diamido-valerianic acid (Jaffe, Drechsel 4 ). This fact 

 renders a search for amido-valerianic acid in the products of 

 pancreatic digestion both interesting and desirable 6 . 



Tyrosine (C 9 H U N0 3 ) 6 . 

 Paroocyphenyl-a-amidopropionic acid 



-PH ! H o 



64 (CH 2 . CH(NH 2 )COOH. 



Occurrence Tyrosine is probably never a constituent of the 



in the organ- healthy living tissues or organs of man and the higher 

 ism - animals, but when found there is either the result of 



putrefactive decomposition or of the action of trypsin on proteid 

 bodies, or it is the result of morbid processes. 



The statement that tyrosine is probably never a constituent oi 

 the healthy organs of the higher animals requires some explanation. 

 Until the researches of Kuhne and his pupil Radziejewski 7 had 

 proved the contrary, it was believed on the strength of the analys 

 of the dead pancreas made by Scherer, Gorup-Besanez and others, 



1 v. Gorup-Besanez, 'Em dem Leucin homologer Kb'rper. Bestandtheil der Bauch- 

 speicheldriise,' Ann. d. Chem. u. Pharm., Vol. xcvm. (1856), p. 15. 



2 v. Gorup-Besanez, Lehrbuch d. physiolog. Chemie, 4te Auflage, Braunschweig, 

 1878, see p. 223. 



3 Jaffe, Ber. d. deutsch. chem. Gesellsch, Vol. x. p. 1925 and xi. p. 406. 



4 Drechsel, Hermann's Handbuch, Vol. v. i, pp. 518, 519. 



5 Since the above was written Dr Max Siegfried's memoir, ' Ueber die chemischen 

 Eigenschaften des reticulirten Gewebes ' (Habilitationsschrift, Leipzig, Dec. 1892), 

 has appeared. He has found that when adenoid tissue, which is absolutely unacted 

 upon by trypsin, is subjected to the action of stannous chloride and hydrochloric acid 

 it yields as a chief product of decomposition amido-valerianic acid, besides ammonia, 

 lysine and lysatinine, but neither leucine nor tyrosine. This discovery emphasises 

 the necessity of the search recommended in the text (Jan. 13, 1893). 



6 The name Tyrosine is derived from rvpos, cheese, and was given to it by its 

 discoverer, Liebig, who first obtained it by fusing cheese with caustic potash. 



7 Iladziejewski, ' Das Vorkommen von Leucin und Tyrosin im normalen Korper,' 

 Virchow's Archiv, Vol. xxxvi. (1866), pp. 1 14. 



