BACTERIAL ENZYMES 111 



requirements for the production of urease on Uschinski's medium, 

 and finds that while bacteria will grow if the sodium asparaginate is 

 present, no urease is formed unless leucine is also added. There does 

 not seem to be any important relation between enzyme production 

 and pathogenicity.*^ 



In general, bacterial proteolytic enzymes resemble trypsin more 

 closely than they do pepsin, acting best in an alkaline medium; but 

 the enzymes extracted from bacterial cultures are very feeble as com- 

 pared with pancreatic trypsin. It is probable that there are several 

 distinct proteolytic enzymes in bacterial cells, gelatinase being a dis- 

 tinct protease (Jordan). ^"^ Abbott and Gildersleeve found that the 

 gelatin-dissolving enzyme of bacteria resists a temperature of 100° C. 

 for as long as fifteen to thirty minutes, but Jordan found that the 

 reaction of the medium modifies greatly this heat resistance. Schmailo- 

 witsch*^ states that some bacteria produce an enzyme acting in acid 

 medium upon gelatin but not upon albumin, and this enzyme carries the 

 digestion only as far as the gelatin-peptone stage, whereas the enzymes 

 acting in an alkaline medium carry the splitting through to leucine, 

 tyrosine, etc. Kendall and Walker*^ state that the proteolytic enzymes 

 of B. proteus are not formed when the bacteria have enough carbo- 

 hj^drate supplied so that they need not depend on proteins for their 

 energy requirements; deaminization is independent of proteolysis 

 and represents intracellular enzjTne action. Plenge^^ suggests that 

 there is a special enzyme digesting nucleoproteins (nuclease). Bac- 

 teria are able to split nucleic acids and to convert amino-purines into 

 oxypurines, but they do not carry the oxidation to uric acid; putre- 

 factive bacteria can slowdy destroy uric acid (Schittenhelm),^'' and 

 B. coll destroys purines. ^^ 



Cacace^- investigated the cleavage products of gelatin and coagu- 

 lated blood when digested by B. anthracis, Staph, pyogenes aureus, 

 and Sarcina aurantiaca, and found that proteoses and peptone are 

 produced, which disappear in the later stages of digestion. Rettger^^ 

 found leucine, tyrosine, tryptophane, as well as phenols, skatole, indole, 

 aromatic oxy-acids, and mercaptan, among the products of bac- 

 terial decomposition of egg-albumen and meat; proteoses and pep- 

 tones appear in the early stages, but later disappear, as also eventually 

 do the leucine, tj-rosine, etc. Choline has also been found in the 



85 Rosenthal and Patai, Cent. f. Bakt., 1914 (73), 406; (74), 369. 



8« Corroborated by Bertiau, Cent. f. Bakt., 1914 (74), 374. 



" Abst. in Biochem. Centr., 1903 (1), 230; see also DeWaele, Cent. f. Bakt., 

 1905 (39), 353. 



8* Jour. Infect. Dis., 1915 (17), 442. See also Berman and Rettger, Jour. 

 Bact., 1918 (3), 367. 



89 Zeit. f. physiol. Chem., 1903 (39), 190. 



90 Zeit. physiol. Chem., 1908 (57), 21. 



»' Siven, Zeit. phvsiol. Chem., 1914 (91), 336. 



92 Cent. f. Bakt., 1901 (30), 244. 



93 Amer. Jour, of Physiol., 1903 (8). 284 



