98 THE: PROTEINS OF THE; WHEAT 



After removing a little tyrosine that first separated, 1.87 grams of serme 

 crystallized out, which, when recrystallized from water, browned at about 

 210 and decomposed at 240. 



Carbon and hydrogen: 0.2308 gram substance, dried at 110, gave o. 2894 gram CO 2 and 



o. 1407 gram H 2 O. 

 Calculated for C 3 H 7 O 3 N, C 34.29, H 6.67 p. ct.; found, C 34.19, H 6.77 p. ct. 



This, with the serine obtained from fraction V, gives a total of 6.22 grams 

 of serine isolated. The mother-liquor from the serine contained consider- 

 able substance, but no oxy-proline or other definite substance could be 

 obtained from it. 



CYSTINE. 



300 grams of glutenin were hydrolyzed in the way described for gliadin 

 (p. 80). After evaporating at low pressure to a sirup, neutralizing the 

 remaining excess of acid with sodium hydroxide, and decolorizing the solu- 

 tion with bone-black, a considerable quantity of tyrosine separated out, 

 which, on examination, was found to contain nearly all the cystine that 

 could be detected in the solution. It was therefore dissolved in 5 per cent 

 sulphuric acid and the cystine precipitated with mercuric sulphate. The 

 mercury precipitate was decomposed with hydrogen sulphide, the solution 

 concentrated somewhat, made alkaline with ammonia and then acid with 

 acetic acid, and an equal volume of alcohol added. The cystine, which sep- 

 arated on standing in characteristic hexagonal plates, weighed only 0.17 

 gram. No more could be obtained. This was dissolved in ammonia and 

 reprecipitated by acetic acid. 



Sulphur : 0.0897 gram substance, dried at 110, gave 0.1730 gram BaSO 4 . 

 Calculated for C 6 H 12 O 4 N 2 S 2 , S 26.68 p. ct.; found, S 26.53 P- ct. 



Although glutenin contains about the same amount of sulphur as gliadin, 

 the amount of cystine obtained from the latter under similar conditions was 

 very much greater. It would seem as if glutenin in fact yields less cystine, 

 though the uncertainties attending the isolation of this substance will not 

 permit of a positive conclusion. 



TYROSINE. 



250 grams of glutenin were boiled with a mixture of 750 grams sulphuric 

 acid and 1500 grams of water for 12 hours. The solution was freed from 

 sulphuric acid by an equivalent amount of barium hydroxide, and after 

 concentrating to 800 cc. allowed to stand for some time. A considerable 

 quantity of tyrosine separated, which was filtered out, the filtrate boiled 

 with barium carbonate in order to expel ammonia, and then concentrated to 

 one-half its original volume. After cooling, the residue of barium carbonate 



