Salts and pH as Probes of the Organization of the two Photosystems

Abstract

The interaction of both types of photosynthetic reaction centers with their natural reductants occurs close to the inner surface of the thylakoid membrane. Hence, in intact thylakoids, the electron accepting sites of the reaction centers are reached by externally added reagents only after they have penetrated the thylakoid membrane. Conversely, cofactors or components of the electron transfer complexes are retained in the thylakoid lumen even after their dissociation unless they are capable of escaping across the surrounding membrane.