THE CHEMICAL PROCESSES IX PLANT RESPIRATION III 



category of enzymes. Yet Bach himself^ proved that the 

 active oxygen passes over to the peroxidase in the case of the 

 activation of oxygenases. After Kostychev- found that perox- 

 idase preparations, hke ferrous salts in the scheme of Manchot, 

 rapidly become exhausted and obviously function not as cata- 

 lysts but as inductors, it was natural to assume that the effect 

 of peroxidase is entirely analogous to that of the ferrous ion. 

 This hypothesis is further confirmed by the fact^ that organic 

 peroxides isolated from various plants as well as hydrogen per- 

 oxide are activated by one and the same preparation of 

 peroxidase. Such a general effect of peroxidase differs markedly 

 from the effect of ordinary enzymes but is easily explained in 

 the sense of coupling by means of an intermediate stage of the 

 inductor. The oxygen passes over to the peroxidase from all 

 activated peroxides and in all cases there is formed the same 

 substance, peroxidase peroxide. Only the chemical nature of 

 this peroxide is important for the subsequent oxidation of plant 

 materials while the intermediate stages of the oxygen activation 

 could be very varied. The investigations of Wolff'* have also 

 brought to light a striking similarity between peroxidase and 

 ferrous ion action. However, one may hardly assume more 

 than an analogy, for the latest investigations of Willstatter and 

 his collaborators^ as to the performance of preparations of pure 

 enzymes have already led to a very active preparation of per- 

 oxidase, entirely free from iron.^ 



1 Bach, A. Ber. d. chem. Ges. 37: 3787. 1904; 38: 1878. 1905; 40: 3185. 1907. 



2 Kostytschew, S. Z. f. physiol. Chem. 67: 116. 1910. 



3 Chodat und Bach. Ber. d. chem. Ges. 35: 3943- 1902; 36: 1758. 1903; Engler, A 

 und Herzog. Z. f. physiol. Chem. 59: 359. 1909. 



< Wolff, J. Contrib. a la connaisance de divers phenomenes oxydasiques. 1910. 



5 Willstatter, R. und A. StoU. Ann. d. Chem. 416: 21. 1918; Willstatter, R. und F. 

 Racke. Ibid. 425: i. 1921; 427: iii. 1922; Willstatter, R., T. Oppenheimer und W. 

 Steibelt. Z. f. physiol. Chem. no: 232. 1920; Willstatter, R. und W. Steibelt. Ibid. 

 hi: 157. 1920; Willstatter, R. und R. Kuhn. Ibid. 116: 53- 1921; Willstatter, R. und 

 W. Csanyi. Ibid. 117: 172. 1921; Willstatter, R., J. Graser und M. Kuhn. Ibid. 123: 

 I. 1922; Willstatter, R. und E. Waldschmidt-Leitz. Ber. d. chem. Ges. 54: 2988. 1921; 

 Willstatter, R. Ibid. 55: 3601. 1922 (A comprehensive review). According to Willstatter 

 the effect of purified peroxidase preparations is purely catalytic. 



'' In a more recent study by "Willstatter and Pollinger (.\nn. d. Chem. 430 : 269- 

 319. 1923) it was found that all active preparations of peroxidase do contain a 

 trace of iron. This almost simultaneous demonstration of iron in both oxidase 

 and glutathione preparations goes far toward the establishment of some theory 

 of vital oxidation which shall include iron as an essential factor. — Ed. 



