ENZYMES AND THEIR ACTION 



Calculation. When a series of comparative tests are made on different tissues 

 or on the same tissue under different conditions it is considered satisfactory to make 

 a comparison of the catalase values upon the basis of the volume of oxygen evolved 

 in a period of two minutes from 5 ex. of neutral hydrogen peroxide by means of i c.c. 

 of a i : 4 chloroform-water extract of the tissue. 



B. Experiments on Anti-Enzymes 



i. Preparation of an Extract of Anti-Pepsin. 1 Grind up a number of intestinal 

 worms (ascaris) 2 with quartz sand in a mortar. Subject this mass to high pressure, 

 filter the resultant juice and treat it with alcohol until a concentration of 60 per 

 cent is reached. If any precipitate forms it should be filtered off 3 and alcohol 

 added to the filtrate until the concentration of alcohol is 85 per cent, or over. The 

 anti-enzyme is precipitated by this concentration. Permit this precipitate to stand 



EX) 



FIG. i. APPARATUS FOR QUANTITATIVE DETERMINATION OF CATALASE. 



for twenty-four hours, then filter it off, wash it with 95 per cent alcohol, absolute 

 alcohol, and ether, in turn, and finally dry the substance over sulphuric acid. The 

 sticky powder which results may be used in this form or may be dissolved in water as 

 desired and the aqueous solution used. 4 



2. Demonstration of Anti-Pepsin. 6 Introduce into a test-tube a few fibrin 

 shreds and equal volumes of pepsin-hydrochloric acid 6 and ascaris extract made as 

 indicated above. Prepare a control tube in which the ascaris extract is replaced by 

 water. Place the tubes at 38C. Ordinarily in one hour the fibrin in the control 

 tube will be completely digested. The fibrin in the tube containing the ascaris 



1 Anti-gastric-protease or anti-acid-protease. 



2 These may be readily obtained from pigs at a slaughter house.^ 



3 This precipitate consists of impurities, the anti-enzyme not being precipitated until a 

 higher concentration of alcohol is reached. 



4 The original ascaris extract possesses much greater activity than either the powder or 

 the aqueous solution. 



6 Martin H. Fischer: Physiology of Alimentation, 1907, p. 134. 



6 Made by bringing 0.015 gram of pepsin into solution in 7 c.c. of water and 0.23 gram 

 of concentrated hydrochloric acid. 



2 



