188 Hydrolysis of the Soluble Protein of Swede Tiirnijys 



5. Estimation and isolation of arginine. 



The filtrate containing the arginine was saturated with baryta, 

 and the precipitate of silver arginine so obtained decomposed in the 

 usual way and the liquid made up to 1000 c.c. 

 50c.c. gave NHg equal to 12-00 c.c. N/10 acid. 

 1000 c.c. would give NHg equal to 240 c.c. N/10 acid 

 = 0-336 grm. N 

 = 1-044 grms. arginine. 



Allowing for portions removed for analysis this equals a percentage 

 of 3-12 of arginine in the protein. 



The solution was freed from sulphuric acid by baryta, and the 

 filtrate neutralised with nitric acid and evaporated down. The copper 

 nitrate double salt was then made by dissolving the arginine nitrate 

 in water, boiling with excess of copper carbonate, and evaporating 

 down nearly to dryness. 



6. Estimation and isolation of lysine. 



The lysine was contained in the filtrate from the precipitate of the 

 silver salts of arginine and histidine as obtained in (3). The barium 

 and silver were removed by means of sulphuric acid and hydrogen 

 sulphide respectively. The solution was evaporated down to 600 c.c. 

 and adjusted to contain 5 per cent, of sulphuric acid. The lysine was 

 now precipitated by means of a 25 per cent, solution of phosphotungstic 

 acid in 5 per cent, sulphuric acid. After twenty-four hours the preci- 

 pitate of lysine phosphotungstate was filtered ol? and well washed with 

 5 per cent, sulphuric acid. The precipitate was then decomposed 

 with hot saturated baryta, and the barium phosphotungstate carefully 

 washed. The alkaline solution of lysine was treated with carbon dioxide 

 to remove the baryta, concentrated, filtered and evaporated nearly to 

 dryness. Water was added, the barium carbonate filtered off and 

 washed, and the filtrate and washings made up to 500 c.c. 



25 c.c. gave NHg equal to 23-82 c.c. N/10 acid 



= 0-03335 grm. N. 

 500 c.c. would contain 0-667 grm. N. 



This weight of nitrogen is equal to 3-478 grms. of lysine, or 10-07 

 per cent, of lysine in the protein. 



All attempts to isolate lysine picrate, however, failed to produce 

 more than enough to account for 4-35 per cent, of lysine. 



