ENZYMES. 69 



GLEY/ LANDSTEiNER 2 ). The serum can attain retarding action toward 

 other enzymes by repeatedly injecting the enzyme into an animal in the 

 same manner as the anti-sera are obtained for bacterial toxines. In 

 this way HILDEBRANDT 3 first obtained an anti-enzyme, namely for 

 emulsin, and MORGENROTH 4 has produced in the same manner an anti- 

 rennin in goats' serum. According to EHRLICH the natural and the arti- 

 ficial anti-bodies are identical, which is not the case in the experiments 

 of MADSEN and W ALBUM, 5 at least for the natural and artificially pro- 

 duced anti-rennin. 



On studying the retardation of tryptic digestion, HEDIN 6 found that 

 in different cases a different process occurs. The retarding action of 

 normal beef serum is connected with the seralbumin (LANDSTEINER/ 

 CATHCART 8 ). In this case the trypsin, according to HEDIN, is in some 

 way or other partly attached in an irreversible manner to the retarding 

 substance (see page 73), because much more trypsin is neutralized 

 when the mixture is made in the order seralbumin-trypsin-substrate, 

 than when the substrate is added to the trypsin before the seralbumin. 

 As above stated, egg albumin and the tryptic digestion products also act 

 retardingly upon tryptic digestion. In this case it is immaterial in 

 what order the bodies are mixed, and the trypsin is therefore taken up 

 in a perfectly reversible manner (enzyme deviation}. On treating ser- 

 albumin with 0.1-0.2-per cent acetic acid at 37 C. it loses the power 

 of attaching trypsin; it has a less retarding action than before, and 

 now indeed in the same manner as egg albumin. 



HEDIN 9 has also found that bone-charcoal has the remarkable ability 

 of adsorbing trypsin, and chiefly in an irreversible manner. From this 

 it follows that charcoal can retard the action of trypsin in a very pro- 

 nounced manner; and many analogies between the retarding action 

 of native seralbumin and that of carbon can be detected. 



Antigens and Anti-bodies. In connection with the retardation of 

 enzyme action we can also call attention to other similar processes. Under 

 the name antigen we include those substances which, when injected 

 into animals, cause the formation of bodies in the organism with which 

 they can in some way or another react. The bodies thus formed are 



1 Compt. 'rend. soc. biol., 49, 845, 1897. 



2 Centralbl. f. Bact., 27, 357, 1900. 



3 Virchow's Arch., 131, 33, 1893. 



4 Centralbl. f . Bakt. u. Parasitenk., 26, 349, 1899. 



5 See Arrhenius Immunochemie, 180. 



8 Zeitschr. f. physiol. Chem., 52, 412, 1907. 



7 Centralbl. f. Bakt., 27, 357, 1900. 



8 Journ. of Physiol., 30, 156, 1903. 



8 Bioch. Journ., 1, 484, 1906; 2, 81, 1907. 



