550 



LIGHT AND LIFE 



TABLE 13 



Effect of FMN and Vitamin K3 on Photophosphorylation 



AND Oxygen Evolution Linked to TPN Reduction 



(Arnon, Whatley, and Allen, 18a) 



thesis by fractionating isolated chloroplasts has recently been described 

 by Trebst, Tsujimoto, and Arnon (153) . The light phase was com- 

 pleted first by the complete chloroplast system, in the absence of CO2, 

 and resulted in an evolution of oxygen accompanied by an accumula- 

 tion of substrate amounts of TPN Ho and ATP in the reaction mix- 

 ture. The green portion of the chloroplasts (grana) was then dis- 

 carded and CO2 was next supplied to the remaining non-green portion 

 of the chloroplasts in the dark. 



As shown in Table 15, in the presence of assimilatory power, i.e., 

 TPNHo and ATP, the chlorophyll-free extract was able to fix Ci'^Oa 

 in the dark. Only feeble C^'^Oo fixation occurred in the dark without 

 the components of assimilatory power (Treatments I and 2) . The 

 dark fixation of CO. by the chlorophyll-free extract supplemented 

 with assimilatory power was comparable with fixation in the light 

 by the complete chloroplast system, to which C^-iOo was supplied at 

 the beginning of the illumination period. Here assimilatory power 

 was formed continuously in the light and used at once for COo fixa- 

 tion (Treatment 3) . Very little COo fixation occurred in the com- 

 plete chloroplast system in the dark (Treatment 4) . 



TABLE 14 



Effect of Phenazine Methosulfate (PMS) on Phosphorylation 



AND Oxygen Evolution Linked to TPN Reduction 



(Arnon, Whatley, and Allen, 18a) 



PMS added 

 (/nmoles) 



none 

 0.003 

 0.01 

 0.1 



P esterified 

 (jumoles) 



4.5 

 6.1 



9.0 

 10.0 



O2 evolved 

 (/xmoles) 



4.0 

 4.0 

 3.2 

 0.8 



