De la Rosa Miguel A, Navarro José A, Díaz-Quintana Antonio, De la Cerda Berta, Molina-Heredia Fernando P, Balme Alexis, Murdoch Piedad del S, Díaz-Moreno Irene, Durán Raúl V, Hervás Manuel
Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla y Consejo Superior de Investigaciones Científicas, Américo Vespucio s/n, E-41092 Seville, Spain.
Bioelectrochemistry. 2002 Jan;55(1-2):41-5. doi: 10.1016/s1567-5394(01)00136-0.
Photosystem I reduction by the soluble metalloproteins cytochrome c(6) and plastocyanin, which are alternatively synthesized by some photosynthetic organisms depending on the relative availability of copper and iron, has been investigated in cyanobacteria, green algae and plants. The reaction mechanism is classified in three different types on the basis of the affinity of the membrane complex towards its electron donor protein. The role of electrostatic interactions in forming an intermediate transient complex, as well as the structural and functional similarities of cytochrome c(6) and plastocyanin are analysed from an evolutionary point of view. The proposal made is that the heme protein was first "discovered" by nature, when iron was much more abundant on the Earth's surface, and replaced by plastocyanin when copper became available because of the oxidizing conditions of the new atmosphere.
