GLOBULINS. 



47 



34. Add a 5 per cent, solution of sodium chloride, drop by drop, 

 till the globulin has jusT dissolved. Divide the solution into three 

 portions, (a), (b) and (c). 



(a) Boil. The protein is coagulated. 



(b) Dilute with about five volumes of distilled water. The 



globulin is partially reprecipitated. 



(c) Treat with an equal volume of saturated ammonium sulphate 



solution. The globulin is reprecipitated. 



35. Add 0-4 per cent. H Cl, drop by drop, till the globulin has 

 just dissolved. Divide the solution into three portions, (d), (e) and 



(d) Add 2 per cent, sodium carbonate solution till the globulin 



is partially reprecipitated (one or two drops only are 

 necessary). Now add a few drops of 5 per cent, sodium 

 chloride. The precipitate of globulin redissolves. 



(e) Boil the solution. The protein is not coagulated. Cool 



under the tap and add enough 2 per cent, sodium carbon- 

 ate to precipitate the metaprotein that has been formed 

 by boiling. Now add a few drops of 5 per cent, sodium 

 chloride. The precipitate of metaprotein does not 

 dissolve. 



(/) Dilute with about five volumes of distilled water, 

 globulin is not thrown out of solution. 



The 



36. Mix about 10 cc. of undiluted serum with an exactly equal 

 quantity of a saturated solution of ammonium sulphate. A thick 

 white precipitate is formed consisting of the whole of the globulin. 

 Filter through a dry filter paper into a dry test-tube. Label the 

 filtrate A. Scrape the precipitate off the paper and treat it with 

 distilled water. The precipitate dissolves, the ammonium sulphate 

 adhering to it forming a dilute salt solution which allows the globulin 

 to go into solution. Boil a portion of this solution. A heat- 

 coagulum is formed. 



37. Filtrate A contains serum-albumin in the presence of 

 half-saturated ammonium sulphate. Apply the following tests : 



(a} Boil a portion. A heat-coagulum is formed, 









ot 



