PHOSPHORYLATION CATALYZED BY PHOSPHODOXIN 229 



.08 



.06 



a> 



o 04 



£ 



.02 



/ 



+ FACTOR 



ENDOGENOUS 



/ 



/ 



J I i_ 



25 50 75 100 125 



/i.grams Bacteriochlorophyll / ml 



Fig. 5. Effect of bacteriochlorophyll concentration on 

 photophosphorylationby R. r?<6rz<»7 chromatophores in 

 the absence and presence of the factor isolated from 

 R. rubnim. 



under argon, probably resulting from a stimulation of the endogenous 

 ATP production under argon (Fig, 4, lower two curves). 



Linearity of ATP production by R. nihrum chromatophores with 

 increasing bacteriochlorophyll concentration (up to 30 //grams) in the 

 presence of the factor is indicated in Fig, 5, 



The usual response of photosynthetic phosphorylation with bacteria 

 to increasing light intensity was observed (Fig, 6) with R. ruhrum 

 chromatophores in the presence of the factor isolated from R. rubrum. 

 Saturation was reached at 500 foot- candles in both the absence (unre- 

 ported data) and presence of the factor. This is about double the sat- 

 uration intensity previously reported for R. rubrum (3) and for 



