EPR spectrum of the isolated b6f complex from C. reinhardtii recorded at Eh = +200 mV. EPR settings were: temperature, 15 K; microwave power, 2.02 mW; microwave frequency, 9.42 GHz; modulation amplitude, 0.003231 mT; sweep time, 83.89 s. The spectral regions of the gx/y signals of high-spin hemes (1), the gz signals of cytochromes b and f (2), and the gz,y,x signals of the Rieske center (3) are indicated. The amplitude in the low-field region has been multiplied by a factor of 5.