272 



ENZYMES OF BACTERIA 



perature for most enzymes is between 35° and 50° C. The destructive temperature 

 was defined by Euler as that temperature at which the enzyme is reduced to 50 per 

 cent of its strength in one hour. This temperature also varies for various enzymes, 

 some bacterial proteases resisting for a brief time even boiling temperature. 



Sunlight is injurious to enzymes in aqueous solution but not in a dry condition, 

 the ultra-violet rays being especially injurious; the action of visible rays is inap- 

 preciable. The destructive action of an electric current is proportional to the current. 



The influence of reaction of the medium upon enzyme action should be measured 

 in the actual concentration of hydrogen ions. The optimum reaction varies consider- 

 ably for the various enzymes, as shown in Table I. 



TABLE I 



Enzyme 



Lipase 



Lipase 



Invertase. . 

 Invertase . . 

 Invertase. . 

 Invertase. . 

 Diastase. . . 

 Diastase. . . 



Urease 



Tryptase. . 

 Proteases. . 

 Proteases. . 

 Tyrosinase . 

 Catalase. . 



Source 



Streptococcus 

 Pneiimococciis 

 Yeast 



Asp. ory-.ae 

 PeniciUiinn 

 Bacteria 

 Asp. oryzae 

 File imococciis 



Bacteria 



Yeast 



Yeast 



Optimum 

 pH 



4-4 

 0-5 



9 



7 



4 



5 



50 



7.0 



4.8 



7.0 



7-2-7-5 

 7.2 



6.7-8.5 

 6.0 



6.5 

 7.0 



Author 



Stevens 



Avery 



Sorensen 



Kuhn 



Josephson 



Avery, Stevens 



Sherman 



Avery 



Lcivgren 



E. Meyer 



Abderhalden and Fodor 



Dernby 



Raper and Wormall 



Michaelis, Sorensen 



The influence of pH upon the action of the enzyme may depend upon its purity. 

 A purified enzymatic preparation may show a different optimum reaction than an 

 impure preparation.' 



It is frequently difficult to differentiate between the injury caused to the enzyme 

 itself (usually irreversible) and the influence upon the reaction velocity of the process 

 (usually reversible). This is especially true of the action of salts upon enzymes. Salts 

 of heavy metals, especially Hg, Ni, Co, Zn, Ag, and Au, are distinctly injurious, the 

 action being reversible, because of the formation of a complex between the enzyme 

 and the cation; when the metal is removed, as by treatment with KCN or with 

 neutral salts, the activity is frequently restored. 



ENZYMES AS ANTIGENS 



The problem of the ability of enzymes to bring about the formation of antibodies 

 attracted at one time considerable attention. There is no doubt that on the injection 

 of enzymes antibodies of a specific nature are formed. This phenomenon can be used 

 to separate not only different enzymes, but also enzymes of different origin. However, 

 in view of the fact that each enzyme consists of an active substance possessing a 

 definite structure and a colloidal carrier, and in view of the fact that the nature of this 



Willstatter, R.: op. oil., p. 1359. 1927. 



