[Pheophytin participation in primary processes of electron transfer in photosystem II reaction centers]

Reversible photoreduction of pheophytin "a" was found in preparations of the Photosystem 2 of green plants, the "primary" electron acceptor of PS-2, Q, being reduced in the dark. Study of this photoreaction showed that pheophytin functions in PS-2 reaction centres (r. c.) as a primary electron acceptor between the primary electron donor. pi 680 and Q. It also permitted specification of the nature and properties of other r. c. components and revealing the similarity in the organization of PS-2 r. c. and r. c. of purpur photosynthesizing bacteria.