275 



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



^-TQH2, and cX -tocopherol levels under various conditions. 



RESTORATION OF ELECTRON- TRANSFER REACTIONS 

 IN EXTRACTED CHLOROPLASTS 



In conjunction with studies of the redox state of quinones under various 

 conditions, extraction and restoration experiments provide information re- 

 garding the site of action of the naturally occurring quinones. 



The results of restoration experiments depend strongly on the solvent 

 used in extracting the lyophylized chloroplasts. Extraction with n-heptane or 

 petroleum ether removes a major portion of PQ-A but very little of the other 

 neutral lipids of interest. On the other hand, acetone removes 90% chloro- 

 phyll, 100% PQ-A and PQ-B, 60% PQ-C and D, and 20% or less of the 

 tocopherylquinones ^^\ Hence, it is expected that wide variations in results 

 would occur between laboratories using the various extraction methods. In 

 addition to extracting a large amount of the quinones and chlorophyll, the 

 acetone treatment results in an apparent alteration of the binding of the 

 chlorophyll remaining in the chloroplast as evidenced by a shift in the ab- 

 sorption spectrum peak from 678 mp to 668 m^ (in aqueous suspension). 



Table III 



Quinone 



Restoration of Photoreductive Activities by Quinones 



Added 

 ^moles 



Acceptor 

 DPIP-AA to Cyt. 



Water to 



NADP(l''^) NADP2,4) 



.(1,4) 



Ferri-(3,4) 

 cyanide 



Extracted 

 Chloroplasts 



Dried 



Chloroplasts 



PQ-A 



PQ-B 



PQ-C 



PQ-D 



PQ-A+D+C 



PQ-C+D 



oc -TQ 



/^-TQ 



aJ-TQ 



none 



none 



0.026 



0.026 



0.013 



0.013 



as above 



as above 



.005 



.009 



.001 



6.6 



28. 

 3.0 



30. 



4.2 

 - 0.6 



23. 

 2.4 

 2.4 

 0.6 



16. 



7.8 



22. 

 ■15. 



14. 



27. 

 -17. 



4.2 

 ■ 5.4 

 -10. 

 ■10. 



17. 



('•) Assayed by the method of Keister et al ^^^ 

 (^) Assayed by the method of Vernon and Zaugg ^^' 

 (^) Assayed by the method of Henninger etal ^^' 

 (^) pmoles reduced/hr/mg chlorophyll 



24. 



240. 



• 6.0 

 15. 

 30. 



• 15. 



72. 

 120. 



96. 

 120. 



290 



640 

 600 

 530 

 500 

 580 



240 

 320 

 840 

 650 



