n. /;. Mcelroy and h. h. seliger 



243 



pH 10 



70C -I96C 



■t; 



540 480 480 



Xm|i 



365 

 375 

 4 15 



460 

 480 



540 



m|i 



Fig 22. Absorption and fluorescence energy level diagram for oxyliiciferin. The 

 measurements were made at various pH values and at various temperatures, as 

 indicated. The blue shift at low temperatures appears to be a highly efficient 

 fluorescent state. 



fluorescence and in intensity with temperature is observed with kici- 

 ferin. In Fig. 23 the fluorescence emission of luciferin at -196°C 

 and at neutral pH is shown in Curve 1. As the temperature is 

 warmed gradually going from curves 1 through 8, one observes the 

 slow disappearance of the 460 m/x peak and a gradual appearance of 

 the 535 m^tt peak. 



In none of these fluorescence measurements of luciferin and oxyluci- 

 ferin under the various conditions described have we observed a 

 fluorescence emission which is comparable to the bioluminescence 

 emission spectrum. However, as the results in Fig. 24 indicate, the 

 adenylic acid derivatives of luciferin and oxyluciferin radically change 

 the emission peaks. LHo-AMP acid fluorescence has an emission peak 

 at 570 millimicrons which corresponds closely with the biolumines- 

 cence emission curve. On the other hand, oxyluciferyl-adenylate 

 fluoresces with a major peak around 460 m^x and a secondary minor 

 peak at around 625 m/x. We shall discuss these data in connection 

 with the mechanism of the light-emitting reaction in a later section. 



