ERRORS IN STUDY OF PEROXIDASES 537 



as oxidizing agents in themselves but acquiring powerful 

 oxidizing influence by contact with the peroxidases, are 

 called oxygenases by Bach and Chodat a term which is 

 obviously not particularly fortunately selected as it suggests, 

 for these substances the idea of a ferment nature which 

 does not belong to them. In their work on vegetable ma- 

 terial of different kinds Bach and Chodat succeeded in 

 separating the oxygenases and peroxidases from each other 

 by fractional precipitation with alcohol, etc. The peroxi- 

 dases, in spite of their presumed enzymic nature, are fairly 

 resistant substances, which can be kept for years under 

 proper conditions ; but the oxygenases are extremely labile 

 and, in accord with their peroxide character, are at once 

 broken up by water with formation of hydrogen peroxide. 

 It is scarcely any wonder that while the peroxidases are met 

 in the vegetable kingdom in very wide, one might almost say 

 general distribution, oxygenases are to be recognized only 

 exceptionally. 3 



No further discussion will be given to the vegetable per- 

 oxidases. What, however, of the distribution of animal 

 peroxydases ? 



Sources of Error in the Study of Peroxidases. In under- 

 taking, some years ago, in association with E. v. Czyhlarz, 4 

 to answer this question, the author recognized at the out- 

 start that the confusion prevailing upon the subject was due 

 to failure to take into consideration a number of important 

 items. 



In the first place, as long as we continue to look upon the 

 peroxidases as ferments, we should insist, too, upon their 

 basic differentiation from the peroxidase-like action of 

 haemoglobin. Guaiaconic acid and similar reagents in the 



3 Literature upon Animal Peroxidases: A. Bach and Chodat, Biochem. Cen- 

 tralbl., 1, 417, 1903; A. Bach, ibid., 9, 1909; Kastle, 1. c., 110-119; Vernon, 

 1. c., pp. 216-217; Oppenheimer, 1. c., 342-349, 353-361, 386-390; F. Samuely, 

 Handb. d. Biochem., 1, 570-572, 1909; E. v. Czyhlarz and O. v. Fiirth, Hof- 

 meister's Beitr., 10, 358, 1907; F. Battelli and L. Stern, 1. c., 217-238. 



4 Czyhlarz and Furth, 1. c. 



