PROTEOSES AND PEPTONES. 137 



cocoll and besides these also leucine and proline although not in quan- 

 tities that could be determined. Of the total nitrogen they found 

 19.7 per cent arginine, 9.1 per cent lysine, 49.2 per cent glycocoll, 9.3 

 percent glutamic acid and 12.7 per cent proline and leucine together. 

 SIEGFRIED has given proof in several ways as to the purity and unity 

 of the peptones isolated by him. 



In another manner, namely by fractional precipitation with metallic salts, 

 especially with mercuric-potassium iodide and the preparation of phenyliso- 

 cyanate compounds, HOFMEISTEK and his pupils STOOKEY, RAPER and ROGO- 

 ZINSKI i have isolated peptones or polypeptide-like bodies from blood proteid. 

 One of these, called arginine-histidine peptone, yielded arginine and histidine as 

 basic hydrolytic products while another yielded chiefly lysine^as basic product 

 and hence was called lysine-peptone. 



From glutin-peptone, SIEGFRIED, on wanning with hydrochloric 

 acid, obtained a base, C2iH 3 9N 9 08, which can also be directly obtained 

 from gelatin. This he calls a kyrin, because it is to be considered a$ a 

 basic protein nucleus, and he calls this special one glutokyrin. The 

 glutokyrin gives the biuret reaction and is considered as a basic peptone. 

 On complete hydrolytic cleavage it yields arginine, lysine, glutamic 

 acid, and glycocoll. Of the total nitrogen two-thirds belong to the 

 bases and one-third to the amino-acids. Recently he with O. PILZ 

 on further hydrolysis has prepared a /3-glutokyrin, which only yielded 

 arginine, lysine and glutamic acid. Similar basic nuclei, protokyrins, 

 have recently been obtained by SIEGFRIED 2 from fibrin and casein, using 

 the same method. Caseinokyrin gives a non-crystalline sulphate, but 

 a crystalline phosphotungstate. The free caseinokyrin has an alkaline 

 reaction, gives the biuret test, and its composition corresponds to the 

 formula C23H47N90s. It yields arginine, lysine, and glutamic acid on 

 cleavage. The basic nitrogen amounts to about 85 per cent of the total 

 nitrogen, and caseinokyrin, behaves in this respect like a protamine. 



Among the known cleavage products of proteins, arginine is the only 

 one which, up to the present, is never absent, and for this reason we 

 designate as proteins only those atomic complexes which contain, besides 

 chained monamino-acids, also arginine, or, more simply, show the prev- 

 iously mentioned imide bindings. Hence caseinokyrine, w r hich yields 

 only arginine, lysine and glutamic acid, and scombrin, which yields 

 only arginine, proline, and alanine, are the simplest known proteins. 



Scombrin belongs to the previously mentioned group of protamines 

 which, according to KossEL, 3 are formed by a successive cleavage of the 



1 Hofmeister's Beitrage, 7, 9, and 11. 



2 Kgl. Sachs. Ges. d. Wiss., Math.-Phys. Klasse, 1903, and Zeitschr. f. physiol 

 Chem., 43, with Pilz., ibid., 58. 

 3 Zeitschr. f. physiol. Chem., 44. 



