492 



APPENDIX 



400 



500 600 650 



Wavelength (mu 



Fig. 8. Rps. spheroides cytochrome b ferro- 



and ferri-, 



absolute spectra (concentration and pH of cytochrome not stated) (6). Re- 

 produced by permission of Biochimica et Biophysica Acta. 



entity, best detectable from the action spectrum of the relief of carbon 

 monoxide inhibition of oxygen uptake by intact bacterial cells (21). 

 Taylor and Horio concluded from the close similarity between such an 

 action spectrum determined with R. rubriim and the absorption spec- 

 trum of R. rubrum CO-ferro-cytochromoid C complex that the two 

 cytochrome types were probably identical (22), It would be of interest 

 to test the obligate photoanaerobe C//rowa^;«;«inthis way to determine 

 if Chromatium cytochromoid C could mimic cytochrome o properties. 

 Cytochrome o activity is widespread among bacteria, including pur- 

 ple bacteria, and deserves intensive study. 



Properties of h- type cytochromes. 



Cytochromes of the b type have been detected in intact cells of 

 photosynthetic bacteria and have been implicated in light- induced 

 electron transfer processes (12,18), Both cells and chromatophore 

 preparations of Rps. palustris and Rps. spheroides shov/ a clearly 



