484 



Atusi Takamiya, Hirosi Obata and Eijiro Yakushiji 



by illumination remain unexplained. In the presence of added sodium hydro- 

 sulfite (anaerobic), there was a slow but detectable dark-conversion of CP 743 

 to CP 668 , resulting in a partial recovery (about 60 - 70%) of the initial non- 

 illuminated form in several hours of incubation. The back reaction-rate in the 

 dark was, however, insignificant compared with that which occurred in the light. 



Ascorbic acid was without effect in the dark. On illumination of CP 743 

 in its presence (alkaline phosphate solution, pH 12; anaerobic), however, there 

 was an almost complete recovery of CP 668 . At pH 7. 8, the light-induced re- 

 covery was sluggish and rather inconsistent. It was noticed that, also in this 

 case, the recovery of the peak at 458 m/i does not accompany the rise of the 

 668 mpi peak. The small shoulder at 645 m/i was also abolished during the 

 incubation in the light in the presence of ascorbate. 



Monochromatic light at 667 m/i, 430 m/i and 465 m/x were effective in 

 inducing the photoconversion from CP 668 to CP 743, and light at 740 m/i and 

 565 m/i for the peak reaction. This fact suggests that these two sets of absorp- 

 tion peaks arise from the same substance, i.e., CP 668 and CP 740, respectively. 



From the above-described facts concerning the interconversion between 

 the dark and illuminated forms of the chlorophyll protein, it was inferred that 

 the changes under investigation involve some oxidation- reduction reaction. 

 This inference leads us to the tentative conclusion that the dark and illuminated 

 forms represent the reduced and oxidized forms, respectively, of the chloro- 

 phyll protein. 



The findings reported here may be of significance in view of the growing 

 interest in far-red absorbing forms of chlorophyll. Similar but not identical 

 substances have been discovered in various green organisms by French^^^, 

 AUenO). Brown (10), Butler(ll), and Lippincott^ ^2)_ On the other hand, an 

 absorption change has been found by Kok^^-^) to occur at 710 m/i in the illuminated 

 chloroplasts. 



The question whether our chlorophyll protein is a product peculiar to 

 Chenopodium album, or whether it occurs generally (when it may occur at lower 

 concentration) and play some physiological role in photosynthesis must await 

 further investigation. 



This work was supported by a grant from the Rockefeller Foundation 

 (GAMN 6208). Part of the experimental work was carried out in the C. F. 

 Kettering Research Laboratory, Yellow Springs, Ohio. 



The authors' thanks are also due to Dr. H. Tamiya, Tokugawa Institute 

 for Biological Research (Tokyo), Dr. K. Okunuki, Osaka University (Osaka) 

 and Dr. Koidzumi, Tohoku University (Sendai), for their friendly support. 



