528 ' SELMAN A. WAKSMAN 



mixture of peptases and ereptases, as Vines (1900-1910) sug- 

 gested for plants. 



Corper and Sweany (1917) claimed that the tubercle bacilli 

 possess a tryptic-like enzyme capable of splitting proteins in 

 alkaline solutions, a weak pepsin-like enzyme capable of split- 

 ting proteins in acid solutions, and an erepsin-like enzyme 

 capable of decomposing peptones in acid solutions. As a matter 

 of fact, the same enzymatic activities are found to hold true 

 also for the molds and the actinomycetes studied, and the ex- 

 planation of the co-existence of the three different enzymes in 

 the same organism can be used here also as an explanation 

 of the peculiar behavior of the enzymes of the microorganisms 

 studied. This would simplify greatly the question as to the 

 nature of the enzymes of microorganisms, but the explanation 

 would be of doubtful importance in explaining the true nature 

 of the enzymes of the organisms studied. Before we are able 

 actually to separate the different enzymes, the only assumption 

 that can be made is that the proteolytic enzymes of microorgan- 

 isms behave in a different manner from animal enzymes and 

 should be placed in a class by themselves. 



SUMMARY 



1. The proteolytic enzymes contained in the fungi studied 

 appear to differ from known proteolytic enzymes of animal 

 origin in the following particulars: 



a. Their range of optimum reaction is greater; a reaction neu- 

 tral to litmus was found to be the optimum one for the activi- 

 ties of the majority of the enzymes studied. 



h. The temperature optimum is somewhat lower. 



c. Although acting best in a neutral or sometimes in a slightly 

 acid medium they differ from animal trypsin in not being pre- 

 cipitated by safranin. 



d. The exoenzymes can pass through a Pasteur-Chamberland 

 filter. 



2. The sugar content of the medium has no influence upon 

 the production of proteolytic exo- and endoenzymes of A. niger. 



