Localization of oxidized 3,3′-diaminobenzidine deposits in chloroplasts

Summary Experiments were carried out in order to localize products of diaminobenzidine in illuminated and non-illuminated isolated pea chloroplasts. The number of particles exposed by deepetching on the endoplasmic surface (ES) of the thylakoid membrane in illuminated chloroplasts was found to be higher than that of non-illuminated ones. A similar result was obtained for protrusions counted on the fractured faces of the corresponding half of the thylakoid membrane (EF). It is suggested that both the particles and the corresponding protrusions are deposits of oxidized diaminobenzidine formed in the light. These results are in agreement with biochemical experiments, indicating that diaminobenzidine donates electrons on the endoplasmic surface (ES) of the thylakoid.