w. D. Mcelroy and j. w. Hastings 



175 



Light Response to Luciferase Concentration 



The results in Fig. 8 indicate that as the enzyme concentration is 

 increased the initial light intensity increases in a hnear fashion. Of 

 interest with respect to the decay reaction, however, is the fact that 

 the time to reach the steady-state baseline intensity decreases with 

 increasing concentration of the enzyme. The rapidity of the decay 



10 20 30 40 50 60 

 TIME- SECONDS 



Fig. 9. The effect of pyrophosphatase on the complexing reaction. Purified inor- 

 ganic pyrophosphatase ( 10, 20, 40, and 80 micrograms protein ) was added 

 to the reaction mixtures ( B, C, D, and E respectively) prior to initiating 

 the reaction with ATP (McElroy et al, 1953). 



reaction has been observed to vary with different enzyme prepara- 

 tions which suggests that a second factor may be involved. By further 

 purification of the luciferase preparation it is possible to show that 

 a second protein as well as Mg++ are essential for the rapid decay. 

 The most effective protein for accelerating this decay reaction which 

 is present in the firefly lanterns in high concentration is inorganic 



