225 



Donald L. Kelster 



120 



100 



I 80 



o 



XT. 

 O 



< 

 (O 



o 



2 4 6 8 



INDOPHENOL CONC, MxlO 



10 12 

 4 



Fig. 5 



4000 8000 



FOOT CANDLES 



Fig. 6 



12000 



Fig, 5. The effect of reduced indophenol concentration 

 on aerobic and anaerobic phosphorylation. The reaction 

 was illuminated in 50 ml Erlenmeyer flasks fitted for 

 flushing with gas. Illumination was provided by 75 watt 

 photoflood lamps which provided 5^00 ft. candles. 

 Curves a and b, gas phase is air. Curves c and d, gas 

 phase is argon. 



Fig. 6, The effect of light intensity on phosphorylation 

 catalyzed by DCI, pyocyanin, and FMN. The reaction 

 mixture contained either 2.6 x IQ-'^M DCI, IQ-'^M FMN, or 

 10~5m pyocyanin and 80 ug chlorophyll in addition to those 

 reagents described in methods. The reaction was illuminated 

 from underneath in Warburg vessels. The light intensity was 

 varied by changing the distance of the light source from 

 the flask and by inserting wire screens. Anaerobic flasks 

 were flushed for 10 mln with argon before illumination. 

 Illumination time was varied so that curves were comparable, 



CONCLUSIONS 



The indophenol dyes have now been shown to catalyze two types 

 of photophosphorylation; a non-cyclic phosphorylation coupled to 

 their reduction, thus placing them in the same category as 

 ferricyanide as a Hill oxidant; and a cyclic photophosphorylation 

 similar to that catalyzed by PMS and pyocyanin. In addition 

 they act as a mediator to supply electrons from ascorbate and 

 thus restore TPN reduction by a system in which oxygen evolution 

 has been blocked or destroyed^ ■'■5) . It appears probable that 

 this site of action and the site where the dye is reoxidized 

 during cyclic phosphorylation are the same. 



The indophenols were also demonstrated to be potent uncouplers 

 of photophosphorylation at concentrations normally used to 



* 



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