INDIVIDUAL GROUPS OF PROTEINS 451 



Legumelin. 



Legumelin has the properties of an albumin and is not precipitated 

 by the dialysis of the vicilin. It therefore remains in solution and is obtained 

 by evaporation in vacuo at 40 or by heat coagulation. 



Globulins from Oil Seeds (Nuts). 



The ground-up nut is treated with petroleum ether to remove the oil 

 or fat. The fat-free residue (10 gm. or more) is treated with twice its weight 

 of 10 percent, sodium chloride solution. The solution is filtered off and 

 poured into a large volume of water, or dialysed. A precipitate of globulin 

 is produced which gradually settles and is purified by solution in salt solution 

 and precipitation with water. It is filtered off and washed with water. 



The globulins of the oil seeds prepared as above are usually amorphous 

 powders, insoluble in water but soluble in salt solutions. They have the 

 general properties of a globulin and show the general reactions of proteins. 



Crystalline Globulins from Oil Seeds. 



(a) Excelsin from Brazil Nuts. 



The nut is ground up and freed from oil as described under edestin. 

 The residue is extracted with 10 per cent, sodium chloride solution and the 

 extract is dialysed. It is thus precipitated slowly from solution and is ob- 

 tained in crystalline hexagonal plates. 



(b) Edestin from Hempseed. 



The seed (i kilo) is crushed and pressed in a hydraulic press to remove 

 the oil. The residue is treated with petroleum ether and again pressed. 

 The fat-free residue is extracted with 1000 c.c. of 5 per cent, sodium chloride 

 solution at 60 and the solution filtered through calico. On cooling a 

 precipitate settles out ; it is filtered off, washed with water and dissolved 

 in 500 c.c. of 5 per cent, sodium chloride solution at 60. On cooling 

 edestin separates in a crystalline form. It is filtered off, washed with salt 

 solution, alcohol and ether and dried in the air. About 100 gm. are obtained 

 from 1000 gm. of hempseed. 



A further quantity of edestin separates if the filtrate be dialysed, but as 

 spheroidal masses and not in the same crystalline state. 



Reeves 1 has shown that these crystalline globulins are more easily ex- 

 tracted from the seeds by ^N (about 7 per cent.) sodium benzoate solution : 



The ground hempseed or minced Brazil nut is treated with petroleum 

 ether, poured upon a Buchner funnel and washed with this solvent till free 

 from oil. The husks of the hempseed are removed by sifting through coarse 

 muslin. 500 gm. of the material are mixed with 500 c.c. of the benzoate 

 solution ; after 30 minutes torn blotting paper is put into the mass so as to 

 make it appear quite dry ; the dry mass is wrapped in filter paper and pressed 

 out in a hydraulic press. 300-400 c.c. of liquid are squeezed out. The solid 

 matter is again extracted with 500 c.c. of solvent and treated in a similar way. 

 A third extraction is necessary in the case of Brazil nuts. The extracts are 

 poured into 10 litres of cold water. Edestin or excelsin settles out on stand- 

 ing in a cool place for 1 2 hours. The clear liquid is decanted and the paste 

 centrifugalised. A compact powder results ; it is washed once or twice with 

 water, once with 95 per cent, alcohol, once with absolute alcohol, and twice 

 with dry ether and transferred to a vacuum desiccator. A product almost 

 completely soluble in 10 per cent, sodium chloride solution is obtained. It 

 can be crystallised from warm sodium chloride solution. Yield : edestin 29 

 per cent., excelsin 20 per cent. 



1 Biochem. J., 1915, 9, 508. ^ 



