ACTION OF THE ENZYMES. 123 



teinase, it contains none of the ordinary intracellular ferments 

 present in simple extracts of the gland itself. Pancreatic 

 juice obtained by PAWLOW'S or some similar method repre- 

 sents, therefore, an excellent solution with which to study 

 :he activities of the alkali-proteinase. 



Alkali-proteinase will act in an alkaline, neutral, or even 

 ? aintly acid medium. The medium acting most favorably has 

 an alkaline reaction. KANITZ/ who has recently investigated 

 this problem, states that the action of the enzyme is largely 

 ndependent of the nature of the alkali or alkaline salt used to 

 obtain the alkaline reaction, and is determined solely by the 

 number of hydro xyl ions present in the solution. A 1/200 



1/70 normal solution of the alkali in regard to the hydro xyl 

 ons is the optimum one. An alkalinity greater than this 

 acts deleteriously upon the enzyme. The ferment acts very 

 well in a neutral medium, but is rapidly destroyed in the 

 )resence of an acid, even of the concentration of the hydro- 

 chloric acid of the gastric juice. 



The nature of the protein upon which alkali-proteinase 

 acts is not without influence upon the rapidity of the splitting 

 3rocess. Unboiled fibrin cannot well be used in making 

 comparative tests with trypsin, as it is too rapidly digested. 

 Boiled fibrin is digested more slowly, and this substance, 

 or boiled white of egg, is ordinarily used in work on this 

 'erment. Even the last-named is rapidly digested by alkali- 

 3roteinase. The protein acted upon does not first swell, 

 as is the case with acid-proteinase, but breaks up at once 

 nto small particles which rapidly go into solution. 



Alkali-proteinase is very sensitive to temperature. It acts 

 :>est at about 40 C., being rapidly destroyed above this 

 point. Below 40 C. the activity of the enzyme falls off 

 gradually, but it is still recognizable even at C. 70 C. 

 s ordinarily given as the highest temperature at which 

 ilkali-proteinase will exhibit any proteolytic activity. 



1 KANITZ. Zeitschr. f. physiol. Chem., 1902, XXXVII, p. 75. 



