w. D. Mcelroy and j. w. Hastings 



TABLE IV 



Effect of Varying Mg++ Ion Concentration on Light Response to ATP 



(McElroy, 19ola) 



173 



Light Response to Luciferin Concentration 



In the presence of excess ATP and Mg++ ions, the intensity of 

 light from the purified enzyme preparation depends upon the luciferin 

 concentration. Figure 7 illustrates this relationship. The initial maxi- 



i/) 



<I 04 as 12 16 



^ LUCIFERIN CONCENTRATION- ML. 



Fig. 7. The effect of luciferin concentration on the initial light intensity and the 

 rate of light intensity decrease (McElroy and Coulombre, 1952). 



mum light response is plotted against the luciferin concentration. In 

 these preparations the light intensity rapidly decreases to a low resid- 

 ual level. The rate of decrease of the light intensity, however, is 

 inversely proportional to the luciferin concentration, i.e.^ at high lucif- 



