DANIEL I. ARNON 



549 



/J 



-\I3 

 12 

 II 



10 



9 



8 



7 



6 



5 



4 



3 



2 



I 







to 



^1 



10 15 20 



20 5 



minutes 



Fig. 23. Photophosphorylation and oxygen evolution by isolated chloroplasts in 

 the presence and absence of vitamin K3 (.\rnon, Whatley, and Allen, 18, 18a). /tA, 

 microatoms. 



of these catalysts which increased ATP formation without markedly 

 depressing oxygen evolution also increased reductive CO2 fixation 

 (see Section 18) . 



18. Sf.paration of Light and Dark Phases of Photosynthesis 

 IN Isolated Chloroplasts 



A special contribution of cell-free photosynthesis to the study of 

 the mechanism of the process has been the experimental separation 

 of the light-dependent phase, in which photosynthetic events proper 

 occur, from the dark phase during which CO2 is assimilated. This 

 separation has already been discussed for bacterial photosynthesis 

 in Section 12. It will now be reviewed for green plants as it has been 

 observed in chloroplasts. The literature on similar investigations with 

 whole cells has been reviewed elsewhere (153) . 



A physical separation of the light and dark phases of photosyn- 



