RECENT WORK ON PROTEIN-HYDROLYSIS 429 



showing gradually increasing differences from the original 

 starch. Analogy points to a course of decomposition of proteids, 

 similar but more complex, as the substrate itself is more complex 

 than starch. 



This line of reasoning has met with considerable support 

 from the investigations of many physiologists since Kuhne's 

 hypothesis was first critically examined. 



Kutscher, applying more modern chemical methods to the 

 investigation of Kuhne's anti-peptone, ascertained that it is not 

 a homogeneous substance at all, but a mixture of bodies which 

 are mainly basic in character. He used as a precipitant a hot 

 saturated solution of phosphotungstic acid, which separated 

 them from the amino-acids, leucin, tyrosin, etc., which were 

 present with them in the digestion. 



These basic bodies, now for the first time found as zymolytic 

 products of proteid, included lysin and lysatin, two bodies 

 which had already been discovered and prepared by Drechsel, 

 and two others which have been named argenin and histidin. 

 The amounts of the several basic substances varied in different 

 cases, but the argenin was generally prominent among them. 



Lysin, as described by Drechsel, is a dextro-rotatory body, 

 apparently having the constitution of diamido-caproic acid, 

 being therefore related to leucin. It loses its power of affecting 

 polarised light when heated with baryta water to 150 C. 

 Lysatin appears to be homologous with either creatin or 

 creatinin. 



Both lysin and lysatin form crystalline salts with various 

 metals, particularly platinum and silver. 



These basic bodies show certain connections with urea 

 which carry our knowledge of the relation between the intake 

 and output of nitrogen somewhat further, pointing to a direct 

 enzymic formation of urea from proteid, as well as the more 

 indirect method of its origination in the tissues of the body. 

 Kossell and Dakin obtained an enzyme from the liver of the 

 dog which is capable of splitting up argenin into ornithin and 

 urea. According to Thompson the latter only is formed in 

 the body by the enzyme, to which the name argenase has 

 been given. 



The close relations existing between lysatin and urea were 

 pointed out by Drechsel, who by heating the former, purified 

 by crystallation of its silver salt, with excess of baryta water, 



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