202 B. CHANCPl, M. BALTSCHEFFSKY, L. SMITH 



chrome, presumably by a residual trace of molecular oxygen in a manner described 

 by Vernon and Kamen in 1953. Slope B is the initial rate of subsequent dark reduc- 

 tion of the cytochrome after illumination (2.75 X 10~* optical density unit per 

 minute). Partially purified preparations of the photochemically active particles 

 which are virtually free of cytochrome oxidase activity still show this phenome- 

 non of accelerated dark reduction of cytochrome c after illumination. 



References 



1. Chance, B., and Smith, L., Nature, 175, 803 (1955). 



2. Duysens, L. M. N., this volume. 



3. Frenkel, J., /. Arn. Cheni. Soc, 76, 5568 (1954). 



4. Kamen, M. D., this volume. 



5. Castor, L. N., and Chance, B., /. Biol Chem., 217, 453 (1955). 



