22 THE PROTEINS OF THE: WHEAT 



THE AQUEOUS EXTRACT OF THE WHEAT EMBRYO. 



The embryo flour, when treated with water, yields a gummy mass, from 

 which a clear extract is secured with difficulty. From 500 grams of meal 

 an extract was obtained with 2000 cc. of water, of which 1400 cc. could be 

 filtered clear. This extract was neutral to litmus, alkaline to lacmoid, and 

 so acid to phenolphthalein that 19 cc. of decinormal alkali were required to 

 neutralize 100 cc. of it to this indicator. 



When a freshly prepared dilute aqueous extract of the recently ground 

 wheat germs is heated in a water-bath, no coagulation occurs, the solution 

 becoming slightly opalescent. If a more concentrated extract, such as may 

 be obtained by treating one part of meal with five parts of water, is thus 

 heated, the entire solution solidifies to a firm, opaque jelly, free from visible 

 particles. If to either of these solutions a very little hydrochloric acid 

 is added previous to heating, an abundant flocculent coagulum separates on 

 heating. 



After standing a while the aqueous extract becomes gradually acid to 

 litmus, so that when heated slowly it becomes turbid at about 50 and a 

 large flocculent coagulum separates at 55. Heated to 65 for some time 

 and filtered, a second coagulum may be obtained on raising the heat from 

 65 to 100. The amount of this second coagulum is about one-third that 

 of the first. 



The coagulated protein is dissolved by o. 5 per cent potassium-hydroxide 

 solution, but not perceptibly by 0.4 per cent hydrochloric acid solution, 

 unless the latter is heated, when a clear transparent jelly is formed. 



Freed from coagulable protein, the aqueous extract still contains a rela- 

 tively large amount of substance which has the reactions of proteose. 



When the concentrated aqueous extract is poured into a large volume of 

 distilled water, a turbidity forms at first, which mostly disappears after 

 shaking, indicating the absence of a notable quantity of globulin held in 

 solution by the salts dissolved from the meal. 



Saturation of the extracts with sodium chloride gives a considerable pre- 

 cipitate, only a small part of which can be redissolved in dilute sodium- 

 chloride solution. When this dissolved part is precipitated by again satu- 

 rating with sodium chloride, it also is converted, to a large extent, into an 

 insoluble form ; the part still remaining in solution is precipitated, like a 

 globulin, by dialysis. 



When the solution, saturated with sodium chloride, is filtered and the 

 diluted filtrate saturated with ammonium sulphate, a part of the precipitate 

 produced, when redissolved in water, is thrown out of solution by saturating 

 with sodium chloride, though before precipitation with ammonium sulphate 

 it was soluble in saturated sodium- chloride solution. 



