516 



LIGHT AND LIFE 



In illuminated cell-free preparations of R. rubrum, Smith and 

 Ramirez (1.H9) and Smith and Baltscheffsky (138) have observed 

 changes in the absorption spectrum of cytochrome c.> that were as- 

 sociated with phosphorylation. Their conclusions (138), that in the 

 facultative anaerobe R. riibrwn the "photosynthetic" cytochrome c, 

 is not a part of the respiratory chain, and that "two different enzyme 

 systems mediate the oxidation of substrates by oxygen and the phos- 

 phorylation of ADP on illumination," are concordant with our dis- 

 tinction between photosynthetic and oxidative phosphorylation in 

 green cells (6-8, 12) . 



A reversible light-induced oxidation of cytochrome Co in cell-free 

 preparations of Chromatiitui — a cytochrome that has been isolated 

 and purified by Bartsch and Kamen (23) — was measured by Nozaki, 



0.5 - 



-J 



400 450 500 550 600 



A (m^i) 



Fig. 6. Difference spectrum (reduced minus oxidized) of purified cytochrome 

 Ca of Cfiromatiuni (Nozaki, Ogata, and Arnon, 114). 



