622 



Thomas Punnett 



REDUCTION, 



— X— X — PHOSPHORYLATION, 



Fig. 3- Reduction, phosphorylation and ATP/2e- ratio accompanying 

 the aerobic p-quinone Hill reaction. 



OTHER PHOSPHORYLATIONS 



Similar stoichiometries have been reported by Arnon (1), by Avron and 

 Jagendorf (2), by Davenport (3) and by Black et al (10) for the NADP Hill 

 reaction, and by Avron (8) and by Kiester (9) for the DCPIP Hill reaction. 



CYCLIC PHOSPHORYLATIONS 



In the case of the different cyclic photophosphorylations , Yin et al (11) 

 have reported that the quantum yields for cyclic and non-cyclic ATP production 

 are the same. George Hoch and I have confirmed these results on the relative 

 quantum yields for the phosphorylations induced by pyocyanine, FMN, menadione, 

 NADP and ferricyanide (Fig. 4). The simplest interpretation of these results 

 is that the same number of phosphorylating sites is functioning in cyclic and 

 non-cyclic electron transport. 



