LESSON IX 



Ferments and Enzymes (concluded} Precipitation by Calcium Phosphate 

 Proteolytic Enzymes. 



Ferments and Enzymes (concluded] 



D. SEPARATION OF ENZYMES (concluded). 



(b) Precipitation by calcium phosphate (Von Briicke). 



(1) Prepare a suspension of fresh yeast in dilute phos- 

 phoric acid (a fairly large quantity of yeast must be used). 



(2) Keep this suspension at 38'5 0. for five to six days. 



(3) Now neutralise it with lime-water: precipitate of 

 calcium phosphate, which carries the enzyme down with it. 



(4) Filter, and thoroughly wash the precipitate with 

 distilled water. 



(5) Dissolve the precipitate in the least possible amount 

 of water, acidulated with hydrochloric acid. 



(6) Dialyse the resulting acid solution, replacing the 

 hydrochloric acid from time to time, so as to keep the 

 solution within the membrane acid. 



(7) When all the calcium phosphate, and eventually the 

 hydrochloric acid, have been removed by dialysis, pour the 



