554 



LIGHT AND LIFE 



T23I-9 

 30" L 



C,5 , no FMN add«d 



'^■"^^ 



i 



PHOSPHOGLY CE R AT E 



PHENOL /WATER - 



Fig. 26. Radioautogiaph of a chromatogram showing products of photosynthetic 

 C'Oj assimilation by illiiniinatcd cliloroplasts in the absence of added FM\ (Tiebsl, 

 Losada, and Arnon, 151). 



between the non-cyclic and cyclic photophosphorylation was main- 

 tained by adding different amounts of one of the catalysts of cyclic 

 photophosphorylation, FMN, vitamin K, or phenazine methosulfate 

 (cf. Tables 13 and 14). Concordant results were also obtained by 

 Trebst et al. (152) with inhibitor experiments. For example, using 

 the uncoupling effect of ammonia (74, 152) on both cyclic and non- 

 cyclic photophosphorylation, it was possible to suppress the forma- 

 tion of ATP by illuminated chloroplasts without inhibiting the 

 reduction of TPN. Under these conditions, CO2 fixation was com- 

 pletely abolished except when the "acceptor" substance for COo was 

 ribulose dijihosphate. In that case a single product, phosphoglyceric 

 acid, was formed by the carboxylase reaction which does not depend 

 on added ATP (cf. review 161). However, no sugar formation 

 occurred because the acid could not be reduced by TPNHo in the 

 absence of ATP. 



