PHOTOPHOSPHORYLATION IN FLASfflNG LIGHT 



209 



+ MPM, (c) + MPM + antimycinA, (d) + MPM + HOQNO. The concen- 

 trations of HOQNO and antimycin A were chosen to give both 100 per 

 cent inhibition of photophosphorylation in the absence of MPM, and at 

 the same time to give almost full recovery of phosphorylation when 

 the inhibitor was added with MPM (under high light intensities). 



AATP/min/BCHL 

 15 



10 



4 6 



Klux ♦ 88A Filter 



10 



Fig. 6. Rates of photophosphorylation in different systems. Ordinate: 

 Pi esterified in moles /min /mole bacteriochlorophyll. Abscissa: light 

 intensity. A: untreated chromatophores, B: + 1.30 x 10-4 M MPM, C: 

 + 1.30 X 10-4 M MPM + 1.12 x 10-7 m ^timycin A. D: + 1.30 x 10-4 

 M MPM + 7.91 x 10-8 M HOQNO. Temperature 24°gs; 



The rates of photophosphorylation in these four systems in the low 

 light intensity range are shown in Fig. 6. Curves A, B, C, and D cor- 

 respond to systems (a), (b), (c), and (d) described above. The compari- 

 son of tangents of these curves at zero light intensity shows the rela- 

 tive quantum efficiencies for the different systems. It is seen from 



