120 THE CHEMICAL CONSTITUTION OF THE PROTEINS 



Arginine. 



In 1886 E. Schulze and E. Steiger obtained a nitrogenous base 

 from the extracts of the germinated cotyledons of Lupinus, which had 

 the composition C 6 H 14 N 4 O 2 , and to which they gave the name arginirie ; 

 it was also found in the seedlings of other plants and is contained in all 

 the vegetable proteins. Shreiner and Shorey have found it in soil. 



Hedin, in 1 894, isolated it from the products of hydrolysis of horn, 

 gelatin, conglutin, vitellin, egg-albumin, blood-serum, caseinogen. He 

 also showed that Drechsel's lysatinine consisted of a mixture of arginine 

 and lysine. From elastin both Bergh and Hedin failed to isolate it, 

 but its presence in this protein was demonstrated by Kossel and 

 Kutscher. Its occurrence in the protamines was shown by Kossel in 

 1 896, and in histone from leucocytes by Lawrow in 1 899. About the 

 same time Kutscher found that it was contained in antipeptone, obtained 

 by the tryptic digestion of fibrin ; it is also formed when protamines are 

 digested by trypsin (Kossel and Matthews). It is present in the free 

 state in ox spleen, fish-flesh and bull's testis (Totani and Katsuyama). 



The identity of the arginine obtained from animal proteins with that 

 from vegetable proteins was at first denied by Gulewitsch, but a little 

 later he showed that they were identical, as also did Schulze. 



The arginine, as it occurs in the proteins, is the dextro-rotatory 

 modification except in fibrin, from which both Kutscher and Cathcart 

 have isolated the inactive form. 



Schulze and Likiernik, in 1891, found that urea was formed when 

 arginine was heated with baryta ; they therefore supposed that arginine 

 was a derivative of guanidine. In 1 897 Schulze and Wiriterstein found 

 that ornithine was also formed ; they isolated it as its dibenzoyl deriva- 

 tive, which was found to be identical with Jaffa's ornithuric acid. 

 Ornithine was regarded as a diaminovalerianic acid ; Schulze and 

 Winterstein showed that it contained two N H 2 groups not attached to 

 neighbouring carbon atoms, and suggested that arginine, as it was a 

 derivative of guanidine and ornithine, might have the following constitu- 

 tion : 



NH 2 NH 2 



NH = C NH CH 2 CH 2 CH 2 -CH COOH 



and that the formation of urea and ornithine might be explained accord- 

 ing to the equation : 



