"122 PHYSIOLOGY OF ALIMENTATION. 



valerianic acid, aspartic- acid, glutamic acid, and lysin. It 

 will be seen later that these compounds are the same as 

 those formed in the action of alkali-proteinase (trypsin) on 

 protein, and we must in consequence ascribe to the gastric 

 juice much greater digestive importance so far as the proteins 

 are concerned than heretofore. 



An essential difference exists, however, in the velocity 

 with which the two enzymes bring about the decomposition 

 of protein into these simpler substances, alkali-proteinase 

 acting much more rapidly than acid-proteinase. The degree 

 of the splitting is also different in the two, trypsin causing 

 the total cleavage of much more of the original protein 

 than pepsin. Trypsin must, therefore, generally speaking, 

 be considered the more powerful of the two ferments. 



5. Alkali-proteinase (trypsin) is the term applied to the 

 proteolytic enzyme found in the pancreatic juice and in a 

 large number of tissues, not only of the human being, but 

 other animals . as well. The ferment was discovered by 

 CLAUDE BERNARD in the middle of the last century, and has 

 since then served as an object of study to scores of investiga- 

 tors. The ferment is present in the pancreatic juice of the 

 human foetus from before birth. Absolutely pure alkali-pro- 

 teinase has never been prepared, and even relatively pure 

 preparations are not easy to obtain. Simple extraction of 

 the fresh, finely minced gland with a saturated sodium chlo- 

 ride solution gives a very active preparation. Extraction of 

 the gland with chloroform water for several days has been 

 recommended by SALKOWSKI. Very active and stabile alco- 

 holic and glycerine extracts of the proteolytic enzyme can 

 also be prepared. MAYS l has studied the problem very 

 carefully, and has perhaps gotten the purest trypsin thus far 

 obtained. For the details of his method the original must 

 be consulted. While pancreatic juice obtained from a pan- 

 creatic fistula contains other ferments besides alkali-pro- 



1 MAYS: Zeitschr, fiir physiologische Chemie. 1903, XXXVIII, p. 428. 



