PHOTOSYNTHETIC PHOSPHORYLATION AND THE ENERGY CONVERSION PROCESS 397 



between the non-cyclic and cyclic photophosphorylation was maintained 

 by adding different amounts of one of the catalysts of cyclic photo- 

 phosphorylation, FMN, vitamin K or phenazine methosulphate (cf. 

 Tables XVII and XVHI). Concordant results were also obtained by 

 Trebst et al. [36] with inhibitor experiments. For example, using the 

 uncoupling effect of ammonia [104, 36] on both cyclic and non-cyclic 

 photophosphorylation, it was possible to suppress the formation of ATP 

 by illuminated chloroplasts without inhibiting the reduction of TPN. 



# 



PHOSPHOGLYCERATE 



P«»OL/ WATER - 



Fig. 33. Radioautograph of a chromatogram showing products of photo- 

 synthetic ^^COo assimilation by illuminated chloroplasts supplied with 0-15 

 (umoles FMN (Trebst, Losada, and Arnon [34]). 



Under these conditions, COg fixation was completely abolished except 

 when the added "acceptor" substance for CO2 was ribulose diphosphate. 

 In that case a single product, phosphoglyceric acid was formed by the 

 carboxylase reaction which does not depend on added ATP (cf. review 

 [166]). However, no sugar formation occurred because the phosphoglyceric 

 acid could not be reduced by TPXH., in the absence of ATP. 



Parallel experiments of Losada et al. [35] on specific enzyme systems 

 in chloroplasts fortified these lines of evidence and supported the con- 

 clusion, that in a reconstituted "catalytic" chloroplast system (in which 



