Structural basis of efficient electron transport between photosynthetic membrane proteins and plastocyanin in spinach revealed using nuclear magnetic resonance.

In the photosynthetic light reactions of plants and cyanobacteria, plastocyanin (Pc) plays a crucial role as an electron carrier and shuttle protein between two membrane protein complexes: cytochrome b(6)f (cyt b(6)f) and photosystem I (PSI). The rapid turnover of Pc between cyt b(6)f and PSI enables the efficient use of light energy. In the Pc-cyt b(6)f and Pc-PSI electron transfer complexes, the electron transfer reactions are accomplished within <10(-4) s.