184 Hydroh/sis of the Soluble Protein of Swede Turnips 



15'73. Another preparation gave 15-64 per cent, of nitrogen in the 

 dry ash-free substance. 



An attempt was made to purify the protein by dissolving it in 0-2 

 per cent, soda and reprecipitating with acid, but the protein would not 

 dissolve. It was realised, however, that the ash present, although 

 abnormally high, would not interfere with the hydrolysis, so the 

 work was carried on without any further attempts being made to get 

 rid of mineral impurities. 



The ash gave qualitative tests for calcium and phosphate. An 

 estimation of the phosphate present showed that it contained 12-05 

 per cent. P2O5 equal to 26-33 per cent, of calcium phosphate. 



An estimation of the sulphur in the protein was carried out by 

 the Benedict method as modified by Wolf and Osterberg^. 



0-4408 gram gave 0-1349 gram BaS04 

 = 0-01853 gram sulphur 

 = 4-204 per cent, sulphur. 

 This result is particularly high, much of the sulphate probably 

 coming from the ash. The protein, however, gave a copious precipitate 

 of lead sulphide when boiled with concentrated caustic soda solution 

 and lead acetate, showing the presence of organic sulphur. 



Aeginine, Histidine, Lysine (and Ammonia). 



The estimations of the diamino-acids were carried out according to 

 the familiar method of Kossel and Kutscher, as modified by Kossel 

 and Patten, and also by Steudel. 



1. Hydrolysis and estimation of protein. 

 Forty grams of the swede protein (equal to 35-96 grams dry 

 ash- free protein) was hydrolysed by boiling under a reflux condenser 

 with a mixture of 120 grams of concentrated sulphuric acid and 240 

 grams of water. The flask was first heated on a water bath for two 

 and a half hours until solution was complete, and then in an oil bath 

 for fifty-six hours at 105° C. The cold hydrolytic liquid was made up 

 to 1 litre with water and two determinations of the nitrogen present 

 in 5 c.c. made by Kjeldahl's method. 



5 c.c. of hydrolytic hquid gave NH3 equal to 20-2 c.c. N/10 acid 



= 0-02828 grm. N. 

 Total N present = 5-656 grms. 

 N calculated in 40 grms. protein = 5-636 grms. 

 1 Biochem. Zeit. xxix, 429, 1910. 



