552 LIGHT AND LIFE 



30' L 



"IS 



8 



i AphOSPHOGLYCERATE - ^^ aHY0RO)CYACETO^e 



4 



PHOSPHATE 



HOSPHATES 

 .FRUCTOSE) 



f 



DIPHOSPHATES 

 '(FRUCTOSE/? ©ULjOSE) 



PHENOL/VWTER- 



Fig. 24. Radioaiitograph of a chromatograra showing products of photosynthetic 

 C"Oo assimilation by illuminated spinach chloioplasts. Experimental conditions 

 as in Treatment 3 of Table 15 (Trebst, Tsujimoto, and Arnon, 153). 



a system different from the one described above, wherein TPNHo 

 and ATP were first generated in substrate amounts in Hght (l^y Re- 

 action 5) and then used later for COg assimilation in the dark. Here 

 TPNH2 and ATP were aheady supplied in excess and a second re- 

 action for generating ATP would be superfluous. However, evidence 

 for the participation of cyclic phosphorylation in CO2 assimilation 

 by isolated chloroplasts was recently obtained by Trebst et al. (151) 

 in a catalytic system, i.e., one in which, as in an intact cell, TPNH.> 

 and ATP were present in catalytic amounts and COo fixation was 

 therefore possible only in the light while TPNHo and ATP were 

 being continuously regenerated at the expense of absorbed light 

 energy. 



CO2 assimilation in this catalytic system was investigated, under 



