PAPAIN-PROTEOLYSIS. 163 



egg-albumin and serum-albumin in neutral, acid, and alkaline 

 solutions peptone is never formed. Further, the opinion is 

 expressed that the formation of peptone by papain is, on bio- 

 logical grounds, not to be expected, since the function of the 

 ferment in the plant consists merely in transforming proteids 

 into soluble compounds adapted for circulation through the 

 open vessels, whereas in pepsin-digestion, on the other hand, 

 the products of proteolysis must be adapted for absorption by 

 osmosis prior to their distribution and utilization in the body. 

 Lastly, it may he mentioned that Dott * in a comparative study 

 of papain and pepsin has likewise found that the former 

 enzyme, unlike pepsin, is not able to form peptone from egg- 

 albumin. If these statements are correct, then, obviously, 

 papain is quite different hi its mode of action from other 

 proteolytic enzymes, and the fact, if such it is, should be clearly 

 established. There would seem to be no great difficulty in 

 arriving at a definite conclusion regarding the matter, and the 

 following experiments have been undertaken with a view to 

 throwing some light upon the question. 



In a preliminary experiment, coagulated egg-albumin (from 

 a dozen eggs) was mixed with 800 c. c. of 0. 2 per cent sodium 

 carbonate solution, 1 gram of commercial papain added, and 

 the mixture, contained in a closed flask with a little thymol, 

 warmed at 40 C. for three days. Further ferment action was 

 then stopped by boiling, the undissolved matter removed by 

 nitration, the filtrate neutralized with acetic acid, filtered from 

 the precipitate which resulted, and further concentrated. 

 From this concentrated fluid the proteoses were precipitated 

 collectively and completely by saturating the fluid while 

 boiling hot with ammonium sulphate, carrying out the 

 saturation in a neutral, acid, and ammoniacal fluid succes- 

 sively, as recommended by Kuhne f for the complete separation 

 of proteoses from peptone. On testing this proteose-free 



* Dott, Comparison of the Digestive Action of Papain and Pepsin. Pharm. 

 J. Transact., liii, p. 758, Edinburgh ; Abstract in Chemisches Centralblatt, 

 1894, i, p. 831. 



t Kuhne: Erfahrungen iiber Albumosen und Peptone, Zeitschrift fur 

 Biologie, 1892, xxix, p. 1. 



