524 



SELMAN A. WAKSMAN 



of Steffens (1900) tend to show that the enzymes of molds are 

 entirely different from animal enzymes. 



Erepsin, as was shown by Cohnheim (1901), Frankel (1916) 

 and other investigators, decomposes not only peptone but also 

 casein, so that the two substances used in the previous experi- 

 ments cannot give us any differentiation between erepsin and 

 other enzymes which could also decompose true proteins. 

 Merck's fibrin and crystalline egg-albumen were therefore used 



TABLE 9 

 Decomposition of fibrin and crystalline egg-albumen by enzymes of microorganisms 



* The presence of amino nitrogen in the crystalline egg-albumen may be due 

 either to the end group of the protein molecule, or to such product combined with 

 a small quantity of ammonia, remaining as a contamination of the protein in 

 the form of (NH4)2S04. 



for the next experiment. The fibrin was introduced, in small 

 pieces into flasks containing 100 cc. of water so as to make one 

 per cent of the liquid, after the proper enzyme has been added. 

 The crystalline egg-albumen was also made up as a 1 per cent 

 solution in water. The exo- and endoenzymes of A. niger, A. 

 ochraceus, P. chrysogenum, and Act. griseus were used for this 

 experiment. 



As is seen from table 9, such true proteins as fibrin and crys- 

 talline egg-albumen are also decomposed by the enzymes of the 



