208 



METABOLISM AND PHYSIOLOGY 

 TABLE 2 



Single flash yield of photophospJiorylatioii and rate of pliotophospJiorylation 

 under continuous illumiiiatioii (both under saturating light intensities) 



Exp. no. 



Single flash yield 



AATP/BChl 

 (mole/mole) 



AATP/cyto- 



chrome 

 (mole/mole) 



Rate under contin- 

 uous illumination 

 AATP/min/BChl 

 (mole/min/mole) 



1 

 2 



3 



Mean 



0.048 

 0.037 

 0.056 

 0.047 



0.92 

 0.71 

 1.07 

 0.90 



6.05 

 4.90 

 8.18 

 6.38 



A: CONTINUOUS ILL. 



B: FLASHING ILL. 



Fig. 5. Recordings of pH change by illumination of R. ruhruni chromatophores. 

 25°C. A: continuous illumination, 8,000 lux + 88A filter, 0.1 pH unit full scale, 

 rate of photophosphorylation -- 6.05 ATP/minA>acteriochlorophyll. B: flashing 

 illumination, 3.58 x 10-2 jouie/cm2/flash + 88A filter, 0.01 pHunit full scale. 



Relative efficiency of light-energy utilization in different systems of 

 phosphorylation 



The comparison of photophosphorylation rates for different phos- 

 phorylating pathways under low intensity continuous illumination indi- 

 cates the relative quantum efficiency of such systems. In this series 

 of experiments the following four systems were studied under condi- 

 tions of limiting light intensity: (a) untreated chromatophores, (b) 



