X, A, 1 Pratt: Papain 31 



No reducing sugars were found in any of these experiments, 

 thus showing the absence of diastase in the latex. It is probable 

 that the reported presence of this enzyme in commercial papain 

 is to be attributed to the adulterants used in its preparation. 



The fresh latex gave a faint blue with tincture of guaiacum, 

 indicating the presence of traces of oxidase. The color darkens 

 to a very pronounced blue upon the addition of hydrogen 

 peroxide, while a control sample boiled for one minute gave no 

 color. The fresh latex gave no color with p-phenylene diamine, 

 but turned deep red at once upon the addition of hydrogen 

 peroxide. Similar results were obtained with Rohmann's re- 

 agent (p-phenylene diamine and alpha naphthol in sodium 

 carbonate solution). 



The fresh latex, therefore, contains considerable amounts of 

 a peroxidase, the presence of which is doubtless responsible 

 for the darkening of color that takes place so readily during 

 drying. 



Digestion mixtures, using olive oil or ethyl acetate as the 

 substrate, were incubated for forty-eight hours in the usual 

 manner employed in testing for fat-splitting enzymes. The 

 presence of lipase could not be definitely established, although 

 in some cases a slight increase of acidity indicated the pos- 

 sibility of traces being present. 



YIELD OF PAPAIN 



It is difficult to estimate the amount of papain that may 

 be obtained from papaya trees grown especially for this purpose. 

 There is no doubt but that proper cultivation greatly increases 

 the available supply of latex and that rich free soil produces 

 plants more capable of recuperating from the effects of tapping. 

 Under ordinary conditions such as prevail in Ceylon, a yield 

 of 1 kilogram of fresh latex may be obtained from about 5 trees. 

 Much depends upon the age of the plant and the maturity of the 

 fruit at the time of tapping. Small immature fruits give a 

 meager flow of latex that coagulates immediately, while larger 

 papayas, about two-thirds mature, give a much larger 

 yield and are to be chosen for tapping. The latex from such 

 fruits does not coagulate rapidly, but freely drips into the col- 

 lecting dish for several minutes following scarification. Two 

 hundred fifty such fruits gave 1 kilogram of fresh latex, 

 representing about 200 grams of well-dried papain. This is a 

 much lower yield than may be obtained under favorable condi- 

 tions. Forty fruits of medium size averaging about 800 grams 

 in weight yielded 1 kilogram of latex, or 3 per cent. An average 



