THE PRINCIPLES OF ENZYME ACTION 65 



action to their stereochemical configuration. He prepared two 

 sets of sugar derivatives which differed from each other solely 

 in the arrangement of their atoms in space (i. e., isomers) and 

 found that one specific enzyme would split members of only 

 one of the varieties, while another enzyme would act only on 

 the variety with the opposite isomeric form. These experi- 

 ments make it very probable that there must be a certain 

 relation of geometrical structure between an enzyme and the 

 substances it acts upon, and leaves little question of its 

 material nature. 



Bredig 1 has found that colloidal solutions of metals have 

 many of the properties of true enzymes, accomplishing many 

 of the decompositions produced by enzymes, being affected by 

 temperatures of nearly the same degree, and even being "poi- 

 soned " by substances that destroy or check enzymes. The 

 only possible explanation of these observations seems to be that 

 the enzyme effects are brought about by surface phenomena. A 

 colloidal solution of platinum, so far as is known, differs from 

 a piece of metallic platinum solely in the enormously great 

 amount of surface it offers in proportion to its weight, and it is 

 well known that surfaces may affect chemical action. Hence 

 we have the possibility that some enzyme actions, at least, may 

 depend upon the existence of a very large surface, and since by 

 no means all colloids are enzymes, that this surface must bear 

 a certain relation in form to the surface of the body that is to 

 be acted upon. 



THE PRINCIPLES OF ENZYME ACTION 



The effects produced by enzymes, which at one time were 

 considered quite unique and remarkable, have now been made 

 comparatively plain, chiefly through the observations of Ost- 

 wald on related chemical reactions ; and by the investigations 

 of Croft Hill, Kastle and Loevenhart, and others, on enzymes, 

 which show that enzyme action is in no way different from 

 chemical action observed independent of enzymes. The funda- 

 mental consideration is that chemical reactions are reversible, 

 that is, that their tendency is to establish an equilibrium, and 

 that the change may be from either side of the equation. The 

 action of enzymes is similar to that of all catalytic agents, that 

 is, they increase the speed of reaction. In the case of such a 

 reaction as that of NaOH and HC1, the reaction is so rapid 

 that the effect of catalyzers could hardly be noticed ; but with 



in Ergebnisse der Physiol., 1902 (Bd. L, Abt. 1), p. 134; also 

 Bergell, Zeit. klin. Med., 1905 (57), 382. 

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