804 R. H. Chittenden — Ferments of Pinewpple Jaice. 



at about 68° C, the turbidity becoming more pronounced at 75°-80° 

 C, followed by the separation of a fine flocculent precipitate at 

 85°-S7"' C. A more complete separation was obtained by adding a 

 drop of acetic acid to the hot fluid. The precipitate produced by 

 heat at about 85° C. was almost wholly insoluble in dilute alkalies. 



This ammonium sulphate precipitate was found wholly free from 

 any proteolytic power either in neutral, acid or alkaline solutions. 

 With the biuret test it gave a very faint violet color. 



Hence, as already stated, saturation of neutral pineapple juice 

 with sodium chloride pi'ecipitates all of the proteolytic ferment 

 present, while there remains in solution some proteid substance, pre- 

 cipitable by ammonium sulphate, having essentially the same chemi- 

 cal properties as the preceding body. Certain points of diiference, 

 however, are noticeable ; thus the body precipitated by sodium 

 chloride shows more of a tendency to sepai-ate from its solution on 

 dialysis, than the substance precipitated by ammonium sulphate. 

 Further, the former body on exposure to heat precipitation separates 

 less readily from its solution, except on the addition of a drop of 

 acid, although the solution shows a heavy turbidity at much the 

 same temperature as the latter body. The one thing, however, to 

 be emphasized here is that the sodium chloride precipitate is 

 strongly proteolytic, while the body separated by ammonium sul- 

 phate is devoid of this property. A more exact study of the chemi- 

 cal status of these two substances is now in progress, but at present 

 nothing more definite can be said. 



Another method of separating the proteolytic ferment is by pre- 

 cipitation with magnesium sulphate. Saturation of neutralized pine- 

 apple juice with this salt gives much the same separation as that 

 produced by saturation with sodium chloride ; i. e. a slight flocky 

 precipitate, readily soluble in water and, after removal of the adher- 

 ent salt, strongly proteolytic. The filtrate still contains some proteid 

 matter, precipitable in small quantity by the addition of sodium 

 sulphate in substance. 



The magnesium sulphate precipitate was examined with the fol- 

 lowing results; it was dissolved in water and dialyzed for several 

 days, until the greater portion of the adherent salt was removed. 

 On testing the solution by heat precipitation, it grew distinctly 

 turbid at 62° C, with separation of flocks at 75° C. This precipi- 

 tate represented practically all of the proteid present in the solution, 

 for boiling the filtrate, with or without acid, failed to give any 

 further separation other than a faint turbidity produced by the 



