[.— Observations on the Digestion of Proteids with Papain. 

 By Lafayette B. Mendel and Frank P. Underbill. 



[From the Sheffield Laboratory of Physiological Chemistry, Yale University.] 



In his recent book on "The Soluble Ferments and Fermentation," 

 J. R. Green writes: "It is uncertain whether pepsin is represented 

 in the vegetable kingdom. All the proteolytic enzymes which have 

 been fully investigated have been found capable of carrying the 

 hydrolysis beyond the stage of peptone. The work of the earlier 

 observers did not include a careful examination of the products of 

 the decomposition, and hence for the present it remains uncertain 

 whether or no some of the ferments belong to the peptic category." 1 

 In another connection the same author says : " On a review of all 

 these vegetable proteolytic enzymes it will be seen that our knowledge 

 is not at present sufficiently definite for us to say whether we have 

 to do with one or many. Some of them may be peptic only, though 

 it seems probable that they are all tryptic. Those which have been 

 at all exhaustively examined undoubtedly carry the proteolysis to the 

 stage of crystalline amides. We do not yet know, again, whethei 

 there is one enzyme only, varying somewhat in its features according 

 to the conditions of its secretion, or whether the different plants dis- 

 cussed yield different varieties of trypsin. Bromelin and papain 

 certainly show very little difference in their behaviour, and one is 

 tempted to pronounce them identical. For the present, however, it is 

 perhaps advisable to leave this question undecided."" 



The proteolytic enzyme obtained from the fruit and juices of the 

 melon-tree Carica papaya and ordinarily termed papain (papayotin), 3 

 has usually been regarded as closely related in its action to the tryp- 

 sin of the pancreas. 4 There are, however, very few r reliable observa- 

 tions on record which permit one to draw a definite conclusion regard- 

 ing the class to which the enzyme may properly be assigned. The 



1 J. R. Green : The Soluble Ferments and Fermentation, 1899, p. 195. 



2 Green: loc, cit. , p. 319. 



3 Moncorvo employed the term "Cariein." (Jahresberieht fiir Thierchemie, 

 1880, x, p. 294.) Other names, such as "Caroid." "Papoid," are applied to 

 commercial preparations of the enzyme. 



4 Neumeister: Lehrbuch der physiologischen Chemie, 1897, pp. 141, 237. 

 Moore : Schaefer's Text-book of Physiology, 1898, i, p. 403. Oppenheimer : Die 

 Fermente und ihre Wirkungen, 1900, p. 135. (The references to the literature 

 on papain and its action are here given.) 



Trans. Conn. Acad., Vol. XI. 1 October, 1901. 



