162 PAPAIN-PROTEOLYSIS. 



process. In this connection it will be remembered, that the 

 corresponding vegetable enzyme bromelin, the proteolytic 

 ferment of pineapple juice, is a true peptone-forming enzyme.* 

 In fact, it resembles trypsin very closely in its ability, under 

 suitable conditions, to transform the proteid undergoing diges- 

 tion into true peptone. It is, of course, hardly to be expected 

 that these vegetable enzymes will prove to be identical in 

 every respect with the corresponding enzymes of animal origin. 

 Indeed, we already know that in the action of bromelin there 

 are certain minor differences at least in the primary or side- 

 products formed as compared with those resulting from gastric 

 and pancreatic digestion. There has, however, been no reason 

 for doubting the ability of papain to form true peptone, 

 although it must be admitted that since exact methods of 

 separating albumoses or proteoses from true peptones have 

 come into use, no one, so far as we are aware, has isolated the 

 pure peptone or determined the extent or rate of its formation 

 in papain-digestion. On the contrary, within the last few 

 years, the statement has come from several sources that papain 

 has no power whatever to form peptone ; that its solvent or 

 digestive action on proteids is limited to the production of 

 proteoses and that peptone is never formed. Thus, Gordon 

 Sharp f states that on warming coagulated egg-albumin with 

 one-tenth its weight of papain and a hundred volumes of 

 water for eighteen hours, no peptone could be detected either 

 by saturating the digestive mixture with ammonium sulphate 

 and testing the filtrate with the biuret test, or by dialyzing 

 the digestive mixture and testing the diffusate (after one 

 hour!) with phosphotungstic acid and by the biuret test. 

 Albumoses, however, were formed. In a second communica- 

 tion | the same writer states that by the action of papain upon 



* Chittenden, On the Proteolytic Action of Bromelin, the Ferment of Pine- 

 apple Juice. Journal of Physiology, 1894, xv, p. 249. 



t Sharp, Papain-digestion : Complete Absence of Peptone. Pharm. J. 

 Transact., liii, p. 633, Edinburgh ; Abstract in Chemisches Centralblatt, 1894, 

 i, p. 512. 



J Sharp, The Action of Papain upon Egg- and Serum-Albumin in Acid and 

 Alkaline Solution. Pharm. J. Transact., liii, p. 757, Edinburgh ; Abstract in 

 Chemisches Centralblatt, 1894, i, p. 830. 



