84 ENZYMES 



results indicate that it can be accounted for largelj^ by the time re- 

 quired for proteolysis to proceed far enough to be detected by chemi- 

 cal means. 



The intracellular proteases are not altogether like either pepsin or 

 trypsin, for they split proteins to the simplest elements, whereas pep- 

 sin carries the digestion only to the peptone stage (under ordinary 

 conditions), and unlike trypsin their action is most marked in a 

 faintly acid medium. Furthermore, the cleavage products seem to 

 contain a much larger proportion of the nitrogen in the form of 

 ammonia and its compounds than is tlie case with trj-ptic digestion, 

 because of the presence of deaminizing enzymes which split the NHg 

 groups out of the amino-aeids and purines. According to Bostock ^^ 

 the greater the acidity the less NH., is formed. It is quite probable 

 that in autolysis several other intracellular enzj^mes are in action, 

 some of which may not be present in pancreatic or gastric juice ; for 

 example, in the liver is an enzjTne, arginase, which splits the urea 

 radical out of the arginine of the proteins (Kossel and Dakiu^^), 

 and the enzymes which disintegrate purines are also absent from the 

 digestive juices. On the whole, however, the products are quite simi- 

 lar to those obtained by tryptic digestion. To give a concrete ex- 

 ample, Dakin ^- detected in the products of autolysis by the kidney 

 in acid solution, the following substances: Ammonia, alanine, 

 a-aminovalerianic acid, leucine, a-pyrollidine carboxylic acid, phenyl- 

 alanine, tyrosine, lysine, histidine, cystine, hypoxanthine, and indole 

 derivatives, including probably tryptophane.^-" The cleavage of sim- 

 ple peptids by different tissues shows characteristic differences, the 

 distribution of the enzyme which splits glycyl-tryptophane having 

 been most studied. During life the cells retain this enzyme, and 

 hence it appears in the body fluids only when the tissues are being 

 rapidly disintegrated (^Mandelbaum).^-*^ 



During autolysis tlie changes are by no means limited to the pro- 

 teins. Glj'cogen is split into glucose very early, and the sugar under- 

 goes further changes. Fats are also split by the lipase, fatty acids 

 being found in autolyzed organs. Reducing substances appear, and 

 as before mentioned, numerous volatile fatty acids are said to be 

 produced. l\Iuch doubt exists concerning tlie supposed formation of 

 volatile fatty acids and ga.ses during autolysis since it was shown by 

 AVolbach, Saiki and Jackson ^-^ that anaerolnc bacteria are almost in- 

 variably present in aseptically removed dog livei*s, for control of auto- 

 lysis by anaerobic cultures has seldom been carried out. However, 



loBiochem. Jour., 1912 (G), 388. 

 11 Zoit. i)liysiol. Cliom., 1004 (42). 181. 

 12. Jour. of'pIiysiolof.'A', 100.3 (30), 84. 



i^'-'llio results of autolysis by dilTcrent tissues are quite dissimilar. See 

 Kashiwaliara. Zcit. phvsiol. Clipm.', 1913 (85), 161. 

 izcMiincli. nip(l. Woeh., 1914 (61). 461. 

 "a Jour. Med. Res., 1909 (21), 267. 



