46 



A. G. FERRARI, B. L. STREHLER, W. E. ARTHUR 



We have undertaken the purification of the material in the alkaline 

 plant extract and have found that it was a chlorophyll a derivative. 

 Subsequently "pure" ethyl chlorophyllide and chlorophyll a were 

 shown to emit a fairly bright light in the presence of base, oxygen, and 

 aldehyde in organic sohition. Moreover, the intensity of the lumines- 

 cence was increased if the solution was illuminated before measurement. 



100 



S 50 



2 3 4 5 6 



Time (Minutes) 



12 3 4 5 6 7 

 (Time Minutes) 



Fig. 1. Time course of luminescence of chlorophyll in methanol (with base and 

 aldehyde). A, chlorophyll in ether added to basic methanol plus formaldehyde. 

 B, solution kept in dark for 12 hours, at the end of which no luminescence was 

 observable. C, sample illuminated after 12-hour dark period. D, sample illumi- 

 nated again. T = 25°C.; 0.1 ml. 0.01 M NaOH in methanol added to 0.5 ml. 

 methanol containing 0.01 ml. 25% formaldehyde; 0.1 ml. chlorophyll solution 

 added o.d. at 665 my., 5 at 666 m^t. 



This suggests that photooxidation reactions are probably involved. 

 Figure 1 illustrates the decay of chemiluminescence and the effect of 

 illumination on chlorophyll luminescence in vivo. 



The evidence indicates that the light-activated luminescence does 

 not require the intactness of chlorophyll ring V (6). After the 

 initial luminescence due to chlorophyll a in basic aldehydic solution 

 disappears completely, a brief exposure to light promotes a reappear- 

 ance of the luminescence even after several days in the dark in base. 

 Under these alkaline conditions the V ring can be presumed to have 

 been hydrolyzed. 



Certain changes in the absorption spectrum of chlorophyll take 

 place during the light emission process. Experiments done in collabora- 



