Exposing the complex III Qo semiquinone radical.

  title={Exposing the complex III Qo semiquinone radical.},
  author={Haibo Zhang and Artur Osyczka and P Leslie Dutton and Christopher C Moser},
  journal={Biochimica et biophysica acta},
  volume={1767 7},
Complex III Qo site semiquinone has been assigned pivotal roles in productive energy-conversion and destructive superoxide generation. After a 30-year search, a genetic heme bH knockout arrests this transient semiquinone EPR radical, revealing the natural engineering balance pitting energy-conserving, short-circuit minimizing, split electron transfer and catalytic speed against damaging oxygen reduction.