58 ENZYMES 



exerted not only against the secreted proteolytic enzymes, pepsin and 

 trypsin, but also against the intracellular enzymes of various organs. 

 We therefore distinguish between normal and immune anti-enzymes. 



It seems highly probable that the resistance of the body tissues to 

 digestion by their own enzymes and by the enzymes of one another 

 depends in some way upon the presence of anti-enzymes in the cells 

 and tissue fluids, for self-digestion of tissues is greatly impeded by 

 serum. ^^ Weiland^^ h^g demonstrated that certain intestinal worms 

 contain a strong antitrypsin, to wliich he attributes their ability to 

 live bathed in pancreatic juice without being digested. ^^ Similar 

 properties have been ascribed by other observers to the cells of the 

 mucosa of the stomach^'* and intestine, and to the mucus itself (de 

 Klug),^^ but the work of Bensley and Harvey^^ indicates that the 

 absence of free acid in the gland cells and lumen is perhaps the chief 

 protection of the stomach from pepsin, Kirchheim^^ holds that the 

 intestines are protected less by anti-enzymes than by rapid absorption 

 and removal of the enzymes, which are really not present in any con- 

 siderable excess in the intestinal contents. The anti-enzjmies seem 

 only to inhibit enzyme action, and not to destroy the enzjane itself.^* 

 Normal anti-enzymes do not seem to be at all specific, according to 

 V. Eisler;^^ that is, human serum is no more resistant to human tryp- 

 sin than is pig serum — ^indeed, it is less so.^" 



Cathcart^^ found that normal antitrypsin is connected with the 

 "albumin fraction" of the serum, i. e., the fraction precipitated between 

 half and full saturation with ammonium sulphate. Globulins do not 

 possess this action, but they are not easily digested. Antitrypsin is 

 found in all varieties of serum, and is little or not at all specific. It is 

 destroyed by Q5-70°C.^^ for one-half hour, but retains its anti-en zj^matic 

 activity after drying, and is equally effective against all sorts of pro- 

 teins. The normal anti-tryptic activity decreases during fasting and 



" Wells, Jour. Med. Research, 1906 (10), 149. 



*'■* Zeit. f. Biol. 1903 (44), 45; see also Dastre and Stassano, Compt. Rend. 

 Soc. Biol., 1903 (55), 130 and 254; and Hamill, Jour, of Physiol., 1900 (33), 479. 



^^ Burge (Jour. Parasitol., 1915 (1), 179) suggests that the protection of para- 

 sites, and perhaps of the alimentary epithelium, depends on the active oxidative 

 properties of these tissues destroying the enzymes. 



6' See Blum and Fuld, Zeit. klin. Med., 1906 (58), 505; Langenskiold, Skand. 

 Arch. Physiol., 1914 (31), 1. 



" Arch, internat. d. physiol., 1907 (5), 297. 



" Biological Bulletin, 1912 (23), 225. 



" Arch. exp. Path. u. Pharm., 1912 (71), 1. 



68 Bayliss and Starling (Jour, of Physiol., 1905 (32), 129; and Meyer, Biochem. 

 Zeit., 1909 (23), 68, oppose the view of Delezenne that the antitryptic action of 

 the blood is due to an antikinase, and believe the antibody acts upon trypsin. 



" Ber. d. Wien. Akad., 1905 (104), 119. 



«" This is contradicted by Glaessner, Hofmeister's Beitriige, 1903 (4), 79. 



8' Jour, of Physiol., 1904 (31), 497; also see Kiimmerer and Aubry, Biochem. 

 Zeit., 1913 (48), 247. 



*- Unless otherwise specified, all temperatures are given'according to the Centi- 

 grade scale. 



