from its dependence on potential , its relationship to the spin-polarized triplet state , and the redox state of the pheophytin acceptor ( ph ) and because it is present in tris-washed chloroplasts but not in untreated chloroplasts , we conclude that the signal is formed when the reaction center is in the state d ( + ) p ( 680 ) ph ( - ) ( p ( 680 ) is the primary chlorophyll donor and d ( + ) is an oxidized donor to p ( 680 ) ) .
C0031512
pheophytin
C0008260
chlorophyll