180 



BIOCHEMISTRY OF FIREFLY LUMINESCENCE 



amount of inorganic triphosphate (5 X 10"^ M) also varied with ATP 

 concentration. The rate at which the maximum Hght intensity was 

 attained, as well as its decay when inorganic triphosphate was added, 

 also varied with the initial ATP concentration. The nature of these 

 changes is evident from Fig. 11. A similar picture was obtained when 

 a constant amount of ATP was used (0.0002 M) and the inorganic 

 triphosphate concentration varied. The results in Fig. 12 demonstrate 



10 



50 



45 

 40 

 35 

 30 



. 



2 25 



X 



20 



15 



(80 

 160 

 140 

 120 

 100 

 80 

 60 



-• • * 



^« ■ I I 



8 10 12 



13 



TIME - MINUTES 



Fig. 13. The luminescent response to the successive addition of luciferase (McEl- 

 roy et al, 1953). 



that the maximum luminescent response as well as the rate varied 

 with the inorganic triphosphate concentration. Higher concentrations 

 were inhibitory when initially added, but with time a certain amount 

 of recovery was obtained, the rate and extent of the recovery depend- 

 ing upon the ATP concentration. It is apparent that the basal level 

 of luminescence attained after adding inorganic triphosphate varied 

 with the concentration of the latter. By adding an excess of ATP it was 

 possible to eliminate the secondary response to inorganic triphosphate, 

 but unfortunately this concentration of ATP inhibited the initial light 



