26 DYNAMICS OF LIVING MATTER 



hydrolized into dextrose and laevulose by a special enzyme, namely, 

 invertase. The dextrose and laevulose undergo alcoholic fermentation 

 by zymase. It has indeed been shown by Lobry de Bruyn that d-man- 

 nose, d-galactose, and d-fructose can easily be transformed into 

 dextrose. If this view is correct, the relation between stereochemical 

 configuration and fermentability is only an apparent one. 



b. The Theory of Intermediary Reactions. 



The facts that the catalyzer is unaltered at the end of the reaction, 

 and that apparently a small quantity of the enzyme can catalyze infi- 

 nitely or comparatively large quantities of the fermentable substance, 

 harmonize with the assumption of intermediary reactions. As an 

 example of the theory of intermediary reactions of enzymes, the oxida- 

 tion of sulphurous acid to sulphuric acid in the presence of nitric acid 

 may be mentioned. Without the presence of nitric acid, sulphuric acid 

 is oxidized but slowly ; but in the presence of nitric acid the latter gives 

 off oxygen to the sulphurous acid, and afterward takes up oxygen 

 again. The intermediary processes seem to be rather complicated and 

 are perhaps not fully known, but it seems that the successive transfer 

 of oxygen from the nitric acid to the sulphurous acid and the reoxida- 

 tion of nitrous acid to nitric acid occur with much greater velocity than 

 the direct oxidation of sulphurous acid by free oxygen. 



Inasmuch as the chemical nature of the enzymes is unknown, it is 

 impossible to ascertain positively whether or not their efficiency is due 

 to intermediary reactions. But there are inorganic catalyzers whose 

 action resembles that of the enzymes, e.g. platinum and other metals, 

 like iridium, osmium, silver, etc. We have already mentioned the fact 

 that platinum acts like lipase in the hydrolysis of ethylbutyrate. The 

 oxidation of alcohol to acetic acid is accelerated by Bacterium aceti 

 as well as by platinum.* A striking analogy between the catalytic action 

 of platinum and enzymes exists in regard to hydrogenperoxide. O. Loew 

 has shown that there is a specific enzyme catalase, which is very general, 

 and which accelerates the decomposition of H 2 O 2 . If this decomposi- 

 tion occurs in the presence of oxidizable substances, the latter, too, are 

 often oxidized. As a rule the process is represented by the equation 



H 2 O 2 = H 2 O + O 



The free atom of oxygen is said to be responsible for the oxidizing action 

 of H 2 O 2 , although Kastle and Loevenhart have expressed a different 

 view.f They quote a number of observations made by previous authors, 



* Bredig enumerates these analogies in his interesting pamphlet on " Anorganischi 

 Fermente" Leipzig, 1901. 



t Kastle and Loevenhart, Am. Chem. Journal, Vol. 29, p. 563, 1903. 



