1 8 PHYSIOLOGICAL CHEMISTRY 



extract may, however, remain unchanged for days, thus indicating the inhibitory 

 influence exerted by the anti-enzyme present in this extract. 



3. Preparation of an Extract of Anti-Trypsin. 1 The extract may be prepared 

 from the intestinal worm, ascaris, according to the directions given on page 17. 



4. Demonstration of Anti-Trypsin. Introduce into a test-tube a few shreds 

 of fibrin and equal volumes of an artificial tryptic solution 2 and the ascaris 

 extract made as described on page 17. Prepare a control tube in which the 

 ascaris extract is replaced by water. Place the two tubes at 38C. 



Ordinarily the fibrin in the control tube will be completely digested 

 in two hours. The fibrin in the tube containing the ascaris extract may, 

 however, remain unchanged for days, thus indicating the inhibitory 

 influence of the anti-enzyme. 



Blood serum also contains anti-trypsin. This may be demonstrated 

 as follows: Introduce equal volumes of serum and artificial tryptic 

 solution (prepared as described above) into a test-tube and add a few 

 shreds of fibrin. Prepare a control tube containing boiled serum. Place 

 in two tubes as 38C. It will be observed that the fibrin in the tube 

 containing the boiled serum digests, whereas that in the other tube does 

 not digest. The anti-trypsin present in the unboiled serum has exerted 

 an inhibitory influence upon the action of the trypsin. 



C. Quantitative Applications 



Methods for the quantitative determination of various enzymes 

 will be found in the following chapters: Amylase (Chapter X); 

 Erepsin (Chapter XI) ; Pepsin (Chapter VIII) ; Trypsin (Chapter X). 

 For the application of Urease to the determination of urea, see 

 Chapters XVI and XXVII. 



1 Anti-pancreatic-protease or anti-alkali-protease. 



2 Made by dissolving 0.04 gram of sodium carbonate and 0.015 gram of trypsin in 8 

 c.c. of water. 



