419 



George Hoch and Olga v. H. Owens 



(16) 

 7.^) are correct either more ATP must be found or the 



schemes for photosynthesis must be revised. 



Since both enhancement effects and respiratory suppres- 

 sion have comrion sensitizations it is conceivable that they 

 have a common origin. The predominate photoreaction at far 

 red wavelengths is an oxidation of P7OO and reduction of a 

 low potential reductant. Recombination of these photoprod- 

 ucts could lead to phosphorylation and therefore inhibition 

 of respiration. It appears some mechanism of this type must 

 operate in the cell to provide growth requirements. The 

 question then, is whether this system is in competition with 

 the oxygen evolution reaction. We would like to suggest 

 that the long wavelength system which we feel provides 

 phosphorylation through recombination is capable of opera- 

 ting independently and is not in competition with oxygen 

 evolution. Rather, it makes some energetic product which 

 assists the oxygen evolution reaction. This product is 

 presumably capable of conversion to ATP. We have tried to 

 outline this in the rather general scheme shown in Figure ?. 



hvl 



hv n 



TPN 



