:>12 J. W. NKWTON ANO M. P. KAMKN 



particles as"chromatophores"; those will carry out both a dark- and 

 a light-enhanced phosphorylation reaction. The supernate from this 

 initial centrif ligation still contains some of the bacteriochlorophyll and 

 carotenoids in smaller particles which can be sedimented by centrif- 

 ugation at 10(),(M)() X g for 90 minutes, leaving a clear 3'eliow super- 

 nate. This shows no light -stinnilatcd phosphorylation but forms some 

 ATP from added ADP in the dark because it contains myokinase 

 activity. The pigmented, small particle fraction sedimented at 

 100,000 X g cannot carry out the light-induced phosphorylation 

 reaction unless some of the supernatant liquid is added to it. The 

 factor present in the supernate from Chromatium extracts which acti- 

 vates the light reaction is a heat-stable dialyzable material, and its 

 effect cannot be duplicated by addition of metals, ashed supernate, 

 ascorbate, menadione, fla\'in mononucleotide, chelating agents, or- 

 ganic acids, pyridine nucleotides, or sulfur compounds when these 

 are added either singly or in combination to the small particle frac- 

 tion. So far, nothing which we have investigated will replace the acti- 

 vating effect of the soluble "supernate factor." In fact none of the 

 known materials which we have added will enhance the light effect, 

 although some compounds have shown inhibitory effects. So far the 

 nature of the soluble, heat-stable supernate factor is unknown. 



Discussion 



Duysens : Did you add DPNH? 



Newton : No, we have not added DPXH. We have added DPX in the presence 

 of various organic acids. We have added cytochrome c and cytochrome isolated 

 from the organisms. We have not added yeast extracts. (Note added in jproof: 

 Subsequent studies have shown that yeast extracts do activate the light phos- 

 phorylation in the small particles.) 



