554 OXIDATION FERMENTS 



Now, however, we come directly to the crucial point of 

 the whole problem, to the question what are the actual oxida- 

 tion functions which these catalytic agents or peroxidases 

 accomplish. 



In the middle of the past century, when attention was 

 directed to the catalytic action of haemoglobin and it became 

 known that a single tiny droplet of blood could change a 

 whole big vesselful of tincture of guaiac like magic to a 

 beautiful blue color, there was hope that we were near to 

 the solution of the great enigma of how the economy accom- 

 plishes its combustion processes. And all the many new 

 color reactions of the peroxidases, which were gradually 

 found out, in the pomp of their introduction invariably fur- 

 nished new food for this hope, and invariably seduced re- 

 search into following their footsteps. The author may con- 

 fess from his own experience that he was never able to 

 break away from the spell of suggestion that the way led 

 hence into the mysteries of the vital processes of oxidation, 

 until he had satisfied himself that a peroxidase, however 

 active it might be, could never break down a single milligram 

 of sugar. There is not the least basis for presuming that the 

 oxidases have anything whatever to do with the vital com- 

 bustion of proteins, carbohydrates and fats. The glitter of 

 color-reactions should not be allowed to deceive us into 

 believing that the functions of the oxidases in reality are of 

 any great importance, and that they extend beyond a very 

 superficial oxidation especially of easily seized hydroxyl- 

 containing cyclic compounds, as the oxidation of formic acid 

 into carbonic acid, etc. This is not to say that such oxida- 

 tions are necessarily physiologically unimportant. The 

 oxidation of the purin bases into uric acid, which may always 

 be attributed to oxidizing ferments, is unquestionably an 

 important process ; and >so, too, the oxidation of cyclic pro- 

 tein cleavage products into melanins, which the author orig- 

 inally proved, and which is now after thorough study of the 

 problem from many sides (cf. Vol . I of this series, pp. 526- 

 528, Chemistry of the Tissues) a part of the assured posses- 



