PAPAIN-PROTEOLYSIS. 171 



formed, but the enzyme was so lacking in vigor that exten- 

 sive proteolysis was impossible, and as a result the formation 

 of peptone progressed very slowly. Still, even under these 

 adverse conditions, some peptone was formed easily recog- 

 nizable by the biuret reaction and the proportion increased 

 slowly with continued digestion. There is therefore even in 

 this experiment no confirmation of the statement that papain 

 is unable to form peptone, but merely a suggestion of the 

 necessity of obtaining an active preparation of the enzyme in 

 order to arrive at a true understanding of its proteolytic power. 

 In a third series of experiments still another preparation of 

 papain was employed : one which preliminary experimentation 

 showed to be quite active. Each mixture contained 150 c.c. of 

 0.25 per cent sodium carbonate saturated with chloroform, 50 

 grams of moist coagulated egg-albumin, and 0.75 gram of 

 papain. A control mixture of albumin, etc., in which the 

 papain was boiled to destroy its activity, was also included hi 

 the series. In this series, however, digestion at 40 C. was 

 continued for longer periods, and it is likewise to be noted 

 that the ratio of dry proteid to the papain employed varied 

 from that in the previous experiments. Further, the method 

 of determining the albumoses and peptone was somewhat 

 different from that previously used. Thus, after separating 

 the undissolved residue and neutralization precipitate, the 

 neutral fluid was concentrated and the albumoses precipitated 

 by saturation of the fluid in the cold with pure zinc sulphate 

 after the method of Bb'mer.* This precipitate was collected 

 on a filter, washed thoroughly with a saturated solution of 

 zinc sulphate, after which it was dissolved in water, the solu- 

 tion made up to a given volume, and the nitrogen determined 

 in a fraction of the fluid by the Kjeldahl method. On multi- 

 plying the values so obtained by the factor 6.25 the amounts 

 of albumoses present were calculated. The figures for pep- 

 tone were obtained by difference, but were verified by deter- 

 mination of the nitrogen hi the zinc sulphate-saturated filtrates. 



* Bomer, Zinksulf at, ein Fallungsmittel fiir Albumosen, Zeitschr. f. analyt. 

 Chem., 1895, p. 562. 



