THE PLANT OXIDASES 229 



SEPARATION OF ENZYME AND INHIBITOR. 



Dialysis of the Iris leaf sap (Atkins, 1913) in presence of 

 toluene was found to remove the reducing agent, for after 

 several days it gave the peroxidase reaction with guaiacum. 

 The catalase reaction was also brought about by the dia- 

 lyzed sap. As dialysis proceeded, the effect of the sap 

 upon the purple colouring matter of the petals was tried 

 daily. That which afforded the peroxidase reaction with 

 guaiacum was found to have altogether lost the power of 

 decolorizing the petal extract. Decolorization was, how- 

 ever, effected by the complete peroxidase system of 

 Hedera leaf. So it appears that either reduction or 

 further oxidation converts the purple pigment into a 

 colourless substance, but the possibility is not excluded 

 that the Hedera peroxidase system obtains oxygen at the 

 expense of the anthocyan. 



The separation of peroxidase and inhibitor can most 

 rapidly be carried out by pouring the leaf sap into strong 

 alcohol, when the enzymes are precipitated. After wash- 

 ing with spirit, they may be dissolved in water, and the 

 peroxidase then gives a blue with guaiacum and per- 

 oxide, the colour being destroyed by addition of the 

 filtrate. 



An inhibitor was also removed by dialysis from the sap 

 of mature leaves of Aspidium filix-mas. 



These reducing agents are active in aqueous solution, 

 and accordingly are not similar to those studied by Keeble, 

 Armstrong, and Jones (1913), which become most active 

 in alcoholic solution, and are thought by those authors 

 to be concerned in the destruction of anthocyan pigments 

 when flowers containing them are immersed in alcohol. 

 Wheldale (1914, 1) and Tswett (1914), while not denying 

 the presence of reducing substances, do not think this 



