STRUCTURAL FACTORS IN POLYMERIZATION 



39 



Fig. I. Peroxiile and pH tiepend- 

 encv of lignin synthesis by Elodea. 



4 8 12 16 20 



INCUBATION TIME (HRS.) 



observation that peroxidase substrates in general suppress or inhibit completely 

 the activity of catalase (14). 



Although it had been assumed from the outset of this investigation that 

 peroxidase was involved in lignin formation, it was necessary, as the point of 

 emphasis shifted toward the aromatic polymer rather than substrate for a 

 particular enzyme, that the participation of this enzyme be established more 

 thoroughly. In addition to the already apparent peroxide dependency of the 

 system, it was subsequently shown that boiling of tissues, cyanide (28), azide 

 and such conventional peroxidase substrates as guaiacol and pyrogallol (29) all 

 inhibited conversion of eugenol to lignin. Finally, the distribution of peroxidase 

 in bean embryo, Elodea, pea root and other tissues as elucidated with pyrogallol 

 coincided with the regions in which eugenol lignin was deposited. The fibrovas- 

 cular system, a natural center of lignification, was one of the principal sites both 

 for peroxidase and synthetic lignin deposition. In view of the suggested role 

 of mushroom phenol oxidases in forming dehydrogenation polymers from sub- 

 stances similar to eugenol (9), both isolated mushroom tyrosinase and in situ 

 potato phenolases were tested with eugenol. In the former system, resinous, 



