188 B. CHANCE 



room temperature (2) and as a slow component in Olson's studies of 

 Chromatium (4). 



In summary, the fast light effect involves principally the "CO- 

 binding pigment" and other unidentified pigments, whereas the slow 

 effect involves definitely less of the "CO-binding pigment" and cyto- 

 chromes of type b and c. This result confirms the idea that the "CO- 

 binding pigment" is the one most closely related to the photochemical 

 process and, insofar as our data show, is the first hemoprotein to react 

 with the oxidizing equivalents produced in the light reaction. The 

 chain of pigments involved in the anaerobic hght effect may be : 



(CO-binding pigment) —*■ cytochromes -> dehydrogenases 



[See Discussion following paper by Britton Chance, Margareta 

 Baltscheffsky, and Lucile Smith, pp. 197-202.] 



References 



1. Duysens, L. M. N., Nature, 173, 692 (1954). 



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



3. Castor, L. N., and Chance, B., J. Biol. Chem., 217, 453 (1955). 



4. Olson, J., this volume. 



