ENZYMES. 63 



that the adsorption process is only reversible with great difficulty or 

 that the enzyme to a certain extent is fastened to the charcoal. That 

 the substrate influences the formation of adsorption combination is 

 shown by the fact that the substrate is also adsorbed by the charcoal. 

 A small part of the adsorbed enzyme can indeed be subsequently 

 displaced on the charcoal by other adsorbable substances and in this way 

 become active again. As various substrates are unequally adsorbed 

 by charcoal the retardation is, therefore, also different in degree. The 

 retardation of the saccharase action by charcoal is the same as for the 

 retardation of the trypsin or rennin action (ERIKSSON x ). 



The action of several enzymes is retarded by normal serum. This 

 was first observed by HAMMARSTEN and RODEN 2 for the action of rennin. 

 Besides this certain constituents of the serum as well as other protein 

 containing fluids have a retarding action and in many such cases the 

 order of the addition of the bodies is important. The retardation by 

 charcoal corresponds to this retardation in several ways and this has 

 led HEDIN 3 to the assumption that the retardation in both cases is brought 

 about by a colloidal reaction (adsorption) between the enzyme and a 

 solid or colloid phase. The facts correspond to this assumption namely 

 that during the action of the retarding substance upon the enzyme 

 the amount of water present is without importance for the final result 

 of retardation. Such a retardation by normal serum or fluids con- 

 taining protein has been observed in the following cases: retardation of 

 trypsin digestion of casein by native seralbumin, 4 retardation of the action 

 of rennin by neutral serum and by white of egg, 5 and the action of sac- 

 charase by serum. 6 Besides this HEDIN 7 found a similar retardation by 

 seralbumin upon the digestion of casein by means of the a-protease of the 

 spleen. The retardation by normal serum or seralbumin has been shown 

 in the cases investigated not to be a specific kind, i.e., a given enzyme 

 is retarded about to the same extent regardless from what species of 

 animal it was prepared. 



A specific retardation due to kind have been observed in the following 

 cases : 



1. The antienzyme obtained by immunization (see page 66) retards 

 in those cases tested, only or chiefly the enzyme used in the imrnuniza- 



., 72,313 (1911). 

 2 Upsala lakarefor. forh., 22, 546 (1887). 



3 Bioch. Journ., 1, 484 (1906); Zeitschr. f. physiol. Chem., 60, 364 (1909); Brgebn. 

 d. Physiol., 9, 433 (1910). 



4 Journ. of Physiol., 32, 390 (1905); Bioch. Journ., 1, 474 (1906). 



6 Zeitschr. f. physiol., 60, 85, 364; 63, 143 (1909). 

 e Ibid., 72,313 (1911). 



7 Hammarsten's Festschr., 1906. 



