Dynamics in the electron transfer complexes of plastocyanin with cytochrome f and cytochrome c

The complex of the photosynthetic redox proteins plastocyanin and cytochromef is compared with that of plastocyanin and cytochrome c. On the basis of nuclear magnetic resonance chemical shift data, it is concluded that the dynamics of the two complexes differs greatly. The complex of plastocyanin and cytochrome f exists predominantly in a single orientation, stabilised by both electrostatic and hydrophobic interactions. The complex of plastocyanin and cytochrome c consists of an ensemble of orientations of a purely electrostatic nature. The results explain the differences in reaction rates between the complexes.