SELMAN A. WAKSMAN 273 



carrier varies with the source of the enzyme, the nature of the antibody varies accord- 

 ingly. Enzymes are bound by the specific substrate much as antigen is bound to 

 antibody. In the first case, however, the binding is followed by catalytic action, the 

 substrate is decomposed, the binding is dissolved, and the enzyme is again liberated 

 to combine with more substrate; the combination of antigen-antibody is permanent, 

 except under the influence of special factors such as specific precipitating antibodies 

 for the proteins contained in the antigen or the antibody carriers, alkaline sugar and 

 salt solutions, etc' 



It has been recently suggested- that the whole system of specific antibody forma- 

 tion can be readily explained by enzyme action. The introduction of complex foreign 

 proteins into the animal body leads to a series of hydrolyses, whereby the complex 

 proteins are broken down into simpler components, similar to the processes taking 

 place in gastro-intestinal digestion. Some of the cleavage products presumably have 

 the same specificity as the original proteins. The hydrolytic processes are followed 

 by processes of synthesis, coagulation, conjugation, and adsorption between the for- 

 eign proteins or their cleavage products and normal humoral or cellular components. 

 Some of these resulting products may have a specific protective action for the body 

 as a whole; others may increase specific susceptibility; still others may be non-specific 

 or even inert. 



OCCURRENCE OF BACTERIAL ENZYMES 



Esterases are enzymes which hydrolyze esters into fatty acids and alcohols; those 

 enzymes which hydrolyze true fats into glycerol and higher fatty acids are usually 

 referred to as lipases; the enzymes which hydrolyze esters of lower fatty acids are 

 frequently spoken of as butyrases. Lecithinase (lecithase), or the enzyme which acts 

 upon lecithin and phosphatides; chlorophyllase, the enzyme acting upon chlorophyll; 

 cholesterinase, acting upon cholesterin ester, and the enzymes which hydrolyze 

 esters of phosphoric acid (phytase, nucleases) and of sulphuric acid (sulphatase), 

 belong to this group. 



A number of bacteria, including B. prodigiosus, B. pyocyaneus, B. fliwrescens, 

 Staph, aureus, B. typhosus, B. tuberculosis, and other acid fast bacteria were found 

 to form lipase readily. •^ Lower esterases are produced by a number of bacteria includ- 

 ing B. typhosus.'^ 



Carbohydrases.— The enzymes which hydrolyze polysaccharides are frequently^ 

 divided into two groups: (i) The polyases acting upon the complex polysaccharides. 

 These include amylase (diastase) which acts upon starch and glycogen, cellulase 

 which acts upon cellulose, inulinase (inulase) acting upon inulin, cytases (hemicellu- 

 lases), including lichenase, which act upon various hemicelluloses, pectinase (pectase) 

 and gelase capable of hydrolyzing pectins and agar-agar, respectively. (2) The 

 hexosidases acting upon di- and tri-saccharides. These include the fructosidases, 



' See chap. Ixx in this volume. 



^ Manwaring, W. H.: J. Immunol., 12, 177, 1926; Scient. Month., p. 362. Oct., 1927. 



^ Eijkman, C: Centralbl. f. BakterioL, I, 29, 841. 1901; ibid , 35, i. 1903; Michaelis, L., and 

 NJakahura, Y.: Ztschr.f. Immunitdtsforsch. n. ex per. Therap., 36, 449. 1923. 



■• Kendall, A. I., and Simonds, J. P.: /. Infect. Dis., 15, 354. 1914. 



^ Oppenheimer, C: Lehrhuch der Enzyme. Leipzig, 1927. 



