The Distribution of Photosynthetic Reactions in the Chloroplast Lamellar System

Plastocyanin is released from chloroplasts by sonication, by passing through the French-press, by extraction with detergents, by treatment with organic solvents and by freezing and thawing. No plastocyanin is liberated during osmotic shock of either class I or class II chloroplasts, or by extraction of class II chloroplasts with dilute solutions of EDTA. Under special conditions it is possible to separate grana and stroma lamellae, which retain plastocyanin. The distribution of plastocyanin between these membrane fractions parallels the distribution of photosystem I. The different reactivity of plastocyanin with various chloroplast membrane preparations is not always correlated to plastocyanin content. Other parameters, like pH, seem to influence the interaction of plastocyanin with the surface of the chloroplast membrane.