EXPERIMENTAL. 37 



PROTEINS OF WHEAT FLOUR SOLUBLE IN SODIUM-CHLORIDE SOLUTION. 



The Globulin of Wheat Flour. 



Beside the proteins soluble in water, 10 per cent sodium-chloride brine 

 extracts from ground wheat kernels a globulin which is present in the seed 

 in small quantity. Ten kilograms of ' ' straight flour ' ' were extracted with 

 34 liters of 10 per cent sodium-chloride solution by suspending the flour in 

 the liquid, stirring frequently, and then allowing the whole to stand at 

 rest over night. The extract, separated from the flour and filtered as clear 

 as possible, had a very slight acid reaction, was of a pink color, very viscid 

 consistence, and formed about one-half of the solution added to the flour. 

 This was saturated with ammonium sulphate, and the resulting precipitate 

 filtered off and dissolved as far as possible in 4 liters of 10 per cent sodium- 

 chloride solution. The exceedingly viscid solution was filtered with diffi- 

 culty, placed in a dialyzer, and left in a stream of running water until the 

 chlorides were removed. As the salts dialyzed out the globulin gradually 

 separated in minute particles, the larger of these being evidently spheroidal 

 in form. This precipitate weighed 5.8 grams. This protein, dissolved in 

 a 10 per cent sodium-chloride solution, when heated slowly, gave a very 

 slight turbidity at 87 , which increased slightly up to 99 . On boiling, 

 some coagulum developed, and on adding acid to the solution filtered from 

 this coagulum a very considerable precipitate formed. 



Dilution of the solution of the globulin in 10 per cent sodium-chloride 

 brine precipitated the protein. Saturation with sodium chloride gave no 

 precipitate. Saturation with magnesium sulphate, and also with ammonium 

 sulphate, completely precipitated the globulin. When dried at no, this 

 preparation, 23, gave, when analyzed, the results which are shown in the 

 table on page 38. 



Another preparation, 24, was made in the same way as the preceding, ex- 

 cept that the precipitation with ammonium sulphate was omitted, the filtered 

 extract being placed at once in dialyzers. Like the preceding solution, this 

 was at first very viscid, but after the removal of the chloride the viscid 

 property was entirely lost. This viscidity can hardly be due to the globulin, 

 for solutions of the precipitated globulin showed no trace of it. The aqueous 

 extract of the flour had no such property, and it is difficult to say to what 

 this was due unless to the presence of carbohydrate. After complete 

 removal of the chlorides the solution was filtered from the precipitate, the 

 latter dissolved in 10 per cent sodium-chloride solution, and the insoluble 

 matter filtered off. The residue so removed consisted chiefly of an insoluble 

 form of the globulin. This was dissolved in o. 2 per cent potassium-hydroxide 

 water, the solution filtered clear, and precipitated by neutralization with 



