ENZYMES, TOXINS, PTOMAINS 51 



The question of specificity of action of bacterial enzymes is not 

 definitely settled. There is some evidence in favor of the view that 

 exo-proteolytic enzymes produced by various bacteria act upon a 

 variety of proteins: thus, the cholera vibrio produces a soluble pro- 

 teolytic enzyme which will digest casein, coagulated blood serum, egg 

 albumen, fibrin and gelatin. Other organisms, as the staphylococcus, 

 produce an exo-enzyme which will hydrolyze casein, coagulated blood 

 serum and gelatin: its action upon other proteins is not definitely 

 established. The important question are the products of hydrolysis 

 of the same protein by proteolytic enzymes from different bacteria 

 the same is not definitely settled; it is probable, however, that the 

 products differ. This suggests that the proteolytic enzymes of bacteria 

 are not mere "catalyzers" which accelerate reactions in relatively 

 unstable substances that would take place spontaneously but much 

 more slowly; these enzymes (proteolytic enzymes) may not only incite 

 reaction, they may guide it, as it were, along lines of cleavage which 

 would not be followed in the absence of this enzyme. The carbo- 

 hydrate and the fat-splitting enzymes have much less latitude in 

 splitting the carbohydrates and fats respectively than the proteolytic 

 enzymes, for these substances are less complex in structure and com- 

 position than the proteins and protein derivatives. 



Fuhrmann 1 has classified enzymes of bacterial origin into four types 

 as follows: 



A. SCHIZASES (HYDROLYTIC) CLEAVAGE ENZYMES. 



1. Proteases, protein-splitting enzymes. Pepsin, Trypsin (Lysins, Coagu- 



2. Carbohydrate-splitting enzymes. Amylase, Cellulase, Pectinase, Gelase, 



Invertase, Lactase. 



3. Glucoside-splitting enzymes. Emulsin (Synaptase). 



4. Fat-splitting enzymes. Lipases (esterases). 



B. OXIDIZING ENZYMES. 



Tyrosinase, Acetic bacteria, Oxydase. 



C. REDUCING ENZYMES. 



Reductases. 



D. FERMENTATION ENZYMES. 



Zymase, Urease, Lactic acid enzyme. 



The bacteriolysins are of particular importance in bacteriology: 

 of the bacteriolysins, those which liberate unchanged hemoglobin 

 from red blood cells (hemolysins) and those which digest hemoglobin 

 (hemodigestins 2 ) are intermediary in their general properties between 

 enzymes and toxins, if indeed there is any tangible distinction between 



1 Vorlesungen uber Bakterienenzyme, Jena, 1907. 



2 Van Loghem, Centralbl. f. Bakteriol., 1912-1913, Ixvii, 410. 



