320 



J. A. BERGERON AND R. C. FULLER 



purified fraction have been studied in some detail [26]. On the basis of the 

 above estimate of particle size, the cytochrome content approaches limiting 

 proportions, that is, i or 2 cytochromes per particle. 



Several years ago it was reported by Williams [41] that photophos- 

 phorylation might have occurred in experiments with crude extracts of a 

 green sulphur bacterium. The observations in our laboratory indicate that 

 light-dependent uptake of phosphate occurs in the "cleared" extract but 

 disappears or is greatly reduced during the course of fractionation. Further 



1.0 

 0.9 

 0.8 



0.7 



>- 



^ 0.6 



UJ 

 Q 



-I 0.5 

 < 



% 0.4 

 0.3 

 0.2 

 0.1 

 0.0 



-y-r-r-t-^^ 



IN H2S SATURATED ACETONE 

 ■IN 0.1 M TRIS BUFFER, PH 7.5 



Fig. II. Quantitative comparison of the spectral change produced by trans- 

 ferring the photosynthetic pigments from the physiological environment of the 

 pigmented particle into solution in HoS-saturated acetone. 



w'ork is needed to establish whether or not the phosphate uptake in the 

 crude extracts really represents ATP formation and what relationship the 

 particles have to this activity. 



Discussion 



The wide range of opinion which exists concerning the importance of 

 structural organization for photosynthesis is illustrated in a recent sym- 

 posium entitled "The Photochemical Apparatus — Its Structure and 

 Function" {BrookJiaven Symp. Biol, ii, 1958). Structural organization 

 above the molecular level was regarded as essential, or important for 

 efficiency, or irrelevant depending upon the type of data and particular 

 aspect of photosynthesis under consideration. Most of the participants, 



