271 



Sakae Katoh and Atusi Takamiya 



In concluding, plastocyanin is another necessary factor which participates 

 in the photochemical activity of chloroplasts, namely, photooxidation of reduced 

 cytochrome c, photoreduction of low redox potential substances in the presence 

 of ascorbate and DPIP, and the Hill reaction with NADP as electron acceptor. 

 The removal of plastocyanin from chloroplasts by various treatments resulted 

 in the loss of these activities which are recovered more or less on addition of 

 plastocyanin. From the experimental facts described above, it may be inferred 

 that this substance is an electron carrier between the two postulated photo- 

 chemical reactions of the photosynthetic mechanism, although the final decision 

 must await further investigation. 



This investigation was supported by a research grant (GAMNS 6208) from 

 Rockefeller Foundation. 



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