PHOSPHORYLATION BY ISOLATED CHLOROPLASTS 



341 



2[H] + [O] + n-ADP 4 nPi 



chloroplasts 



Sum: hv + n-ADP + nP.- 



^ H2O + n-ATP 

 — > /I- ATP 



(2) 

 (3) 



in which [H] and [O] represent, respectively, the reduced and oxi- 

 dized products of the photolysis of water by the chloroplasts. The 



20 - 



16 





o> 



s 



J? 



o 



E 



o 8 

 u 



o AEROBIC 

 • ANAEROBIC 



DARK 



20 

 minutes 



Fig. 1. Light dependence of photosynthetic phosphorylation by broken chloro- 

 plasts. The reaction mixture contained broken chloroplasts (chlorophyll con- 

 tent = 0.5 mg.), 40 mM tris (hydroxymethyl) amino methane, pH 7.4, 20 mM 

 potassium phosphate, pH 7.2, 20 /iM adenosine-5-phosphate, pH 7.4, 10 fiM 

 MgCU, 10 fiM sodium ascorbate, 0.01 fxM FMN, and 0.3 fxM vitamin K5, made 

 to a total volume of 3 ml. with water. The reaction was carried out at 15°C. under 

 nitrogen or air. Estimation.s of the phosphorylation were made as described 

 previously (2,5). 



