LIGHT-DEPENDENT REDUCTIONS 287 



oxidized product formed in this reaction is not known, we cannot 

 interpret the potential changes in stoichiometric terms. 



Discussion 



Frenkel : Did you see any evidence for oxygen evolution in this? 



Vishniac : I didn't look for it. 



Frenkel : You would not expect it? 



Vishniac: Something must be oxidized to balance the reduction, but this is 

 rather rough treatment for a chloroplast to expect oxygen evolution. 



Frenkel : Has it worked with ferricyanide? 



Vishniac : Originally I reported that there was an effect of ferricyanide, and I 

 thought it participated stoichiometrically by being oxidized, but this is not so. 

 In these experiments ferricyanide was added simply to have an electrode-active 

 electron carrier. 



Rabinowitch: These figures refer to a certain time; if you had waited longer 

 would you have obtained more? 



Vishniac : The actual time of these experiments is 20 minutes. I have not run 

 any longer experiment, but in 10 minutes I get about 1 n^l, that is, one-halt of this. 



Rosenberg : Does the alcohol extract of chlorophyll before reconstituting with 

 the protein give the fluorescence that is expected of regular alcohol solutions? 



Vishniac : I don't know. 



Rosenberg : You can generally see this with your eye. 



French : Does pure chlorophj'U work too? 



Vishniac : I have not tried that. 



Reference 



1. Spikes, J. D., Lumry, R., Rieske, J. S., and Marcus, R. J., Plant Physiol, 29, 

 161 (1954). 



