620 



Thomas Punnett 



If this conclusion is correct, the next question is whether one obtains 

 constant stoichiometry by using ATP/2e- (total) and what is the value of this 

 ratio. The value we have found, 0.70 to 0.85, is in agreement with work 

 published earlier. We have also found in these studies that the uncorrected 

 ATP/2e- ratio was relatively constant over a wide range of conditions. In the 

 ferricyanide Hill reaction, the ratio increased slightly from pH 6.8 to 7.6 

 and was constant to pH 8.7 (Fig. 1). 



I 



600 



400' 



t 



oo 



KORRECTED) 



-x^ 



(UNCORRECTED) 

 .x_ X X- 



'X— — 



7.5 7.7 



Fig. 1- Reduction, phosphorylation and ATP/2e- ratio accompanying 

 the ferricyanide Hill reaction. 



At pH 8.0 the ratio was constant when the ferricyanide concentration was 

 varied from 20 ^M/L to 2.2 mM/L. (Fig. 2). The ratio was constant over a 

 wide range of light intensities (done in conjunction with Dr. T.T. Bannister), 

 though it dropped sharply at low intensity as reported by Shen and Shen (7), 

 and by Turner et al (6) . 



