ENZYMES AND THEIR ACTION. 7 



and that the change in one direction is counterbalanced by the 

 change in the opposite direction. Pancreatic lipase was one of the 

 first enzymes to have the reversibility of its reaction clearly demon- 

 strated. 1 A knowledge of the fact that lipase possesses this rever- 

 sibility of action is of extreme physiological importance and aids 

 us materially in the explanation of the processes involved in the 

 digestion, absorption and deposition of fats in the animal organ- 

 ism (see p. 133). 



In respect to many enzymes it has been found that the law gov- 

 erning the action of inorganic catalyzers is directly applicable, i. e., 

 that the intensity is almost directly proportional to the concentra- 

 tion of the enzyme. In the case of enzymes, however, there is a 

 difference in that a maximum intensity is soon reached and that 

 subsequent concentration of the enzyme is productive of no further 

 increase in intensity. The enzymes which have been shown to 

 obey this linear law are lipase, invertase, rennin and trypsin. In 

 certain instances, where this law of direct proportionality between 

 the intensity of action and the concentration of enzyme does not 

 hold, it has been found that the law of Schutz, first experimentally 

 demonstrated by E. Schutz, was applicable. This is to the effect 

 that the intensity is directly proportional to the square root of 

 the concentration, or conversely, that the relative concentrations of 

 enzymes are directly proportional to the squares of the intensities. 2 



It has been shown that there are certain substances which possess 

 the property of directly inhibiting or preventing the action of a 

 catalyzer. These are called anti-catalyzers or paralyzers and have 

 been compared to the anti-toxins. Related to this class of anti- 

 catalytic agents stand the anti-enzymes. The first anti-enzyme to 

 be reported was the anti-rennin of Morgenroth. This was pro- 

 duced by injecting into an animal increasing doses of rennet solu- 

 tion, whereupon an "anti" substance was subsequently found both 

 in the serum and in the milk, which prevented the enzyme rennin 

 from exerting its normal activity in the presence of caseinogen. 

 In other words, anti-rennin had been formed in the serum of the 

 animal, 3 through the repeated injections of rennet solution. Since 

 the discovery of this anti-enzyme, anti-bodies have been demon- 

 strated for pepsin, trypsin, lipase, urease, amylase, laccase, tyro- 

 sinase, emulsin, papain, and thrombin. According to Weinland, 



x The principle was first demonstrated in connection with the enzyme maltase 

 (see p. 55). 



2 This law of Schutz is not generally applicable. 



3 Serum is normally anti-tryptic. 



