EVIDENCE FOR THE ROLE OF SEVERAL QUINONES IN THE ELECTRON 

 TRANSPORT SYSTEM OF CHLOROPLASTS 



R. A. Dilley, M. D. Henninger and F. L. Crane 



PROPERTIES OF CHLOROPLAST QUINONES 



Present evidence indicates that there are four compounds of the plasto- 

 quinone type in spinach chloroplasts '^\ In addition, there occurs o<- ^- 

 and 2J-tocopherylquinones and vitamin K^ ^^' '^\ Hereafter, the plasto- 

 quinones will be abbreviated PQ-A-B, etc; and the tocopherylquinones 

 oi- >^-TQ, etc. Table I lists chromatographic, spectrophotometric, and 

 melting point data of these quinones. The PQ-C and -D data represent the 

 best preparations to date and further purification may be possible. 



The four plastoquinones appear to be widely distributed in the plant king- 

 dom. They have all been found in a variety of species including mono- and 

 dicotyledon types and in the green algae Chlamydomonas r einhardi . 



Table I 

 Properties of Spinach Chloroplast Quinones 



Quinone Rf 



Absorbance 

 Maximum 

 mjj in ETOH 



PQ-A 0.74 255 



PQ-B 0.78 255 



PQ-C 0. 49 262 



PQ-D 0.40 262 



of-TQ 0.37 261, 269 



/?-TQ 0.33 261 



y-TQ 0.25 258 



Vit. Ki 0. 80 241, 261 



249, 269 



F 1% 



^ 1 cm 

 at A max. 



246 

 202 

 96 

 55 

 414 

 430 

 430 



Thin layers (250 p) of silica gel G, chloroform as solvent. 



273 



