269 



Sakae Katoh and Atusi Takamiya 



dye is essentially different from that of DPIP. transferring electron between 

 ascorbate and the oxidizing site of chloroplasts. 



0.03 004 0.05 0.1 0.2 03 4 05 



^mole DPIP 



1.0 1.5 



Fig. 3. Effect of plastocyanin on photoreduction of 

 indigo carmine in the presence of various con- 

 centration of DPIP 



As will be seen in Table III, plastocyanin also stimulates the photoreduc- 

 tion of other low potential substances, such as FMN and NADP in the presence 

 of ascorbate and DPIP. 



TABLE III 



Effect of Plastocyanin on the Photoreduction of FMN and NADP 

 in the Presence of Ascorbate-DPIP Couple 



Electron acceptor 



FMN 

 FMN 



NADP 

 NADP 

 NADP 

 NADP 



DCMU 



Ascorbate 

 + DPIP 



+ 

 + 



jimole reduced 

 mg chl. hour 

 - PC + PC 



