The cytochrome f-b electron-transport complex. A common link between photosynthesis and respiration in the cyanobacterium Anacystis nidulans.

Reduced-minus-oxidized difference spectra were recorded on particle preparations of the cyanobacterium Anacystis nidulans. Physiological oxidation of anaerobic membranes was effected either by O2 or by light. In both cases the spectral changes observed in the 550-570nm region were essentially the same. The results were confirmed by dual-wavelength spectrophotometry. It is concluded that a membrane-bound cytochrome f-b complex participates in both respiratory and photosynthetic elevtron transport.