The Hill reaction of chloroplasts isolated from glutaraldehyde-fixed spinach leaves.

Abstract

Quantum conversion leading to O2 evolution in the Hill reaction can occur in chloroplasts isolated from glutar aldehyde-fixed leaves with about 25% the efficiency of unfixed chloroplasts. The Hill reaction seems normal in that it is DCMU[3-(3,4-dichlorophenyl)-l,l-dimethylurea]-inhibited, its rate is dependent on the present of phosphorylation acceptors or uncouplers, and it exhibits a red drop in efficiency. The fixed chloroplasts do not change morphology upon acetone extraction, and therefore offer the possibility of performing lipid reconstitution experiments. Glutaraldehyde-fixed Chlorella cells are also active in the DCPIP [2,6-dichlorophenolindophenolJ Hill re-action. Quantum conversion and electron transport in photosynthesis is propably explainable in terms of a rigid protein framework with lipid dispersed through. Conformational changes as such are not necessary for quantum conversion leading to oxygen evolution and dye reduction.