On the Reconstitution of Photophosphorylation in CF1-Extracted Chloroplasts

Abstract
1. A method for the reproducible preparation of CF1-depleted thylakoid membranes was established. By repeated washes with pyrophosphate solution and subsequent treatment with sucrose media, containing micromolar concentrations of Ca2+ or Mg2+, different degrees of CF1 depletion and uncoupling were adjusted. 2. The membranes were completely uncoupled when about 50% CF1 was removed. Re-coupling with isolated CF1 was maximal at this point. It decreased with progressive CF1 extraction. 3. The re-attached CF1 particles regained their ability of energy-dependent adenine nucleotide exchange, an essential reaction in photophosphorylation. 4. CF1-depleted membranes showed two main morphological alterations, a. unstacknig of the grana, and b. a perforation of the thylakoid membranes in those chloroplasts which showed a poor recoupling activity. Whereas CF1-depletion and unstacking were found to be reversible, the formation of holes was an irreversible effect. 5. The decreasing re-coupling activity was discussed in context to the irreversible perforation of the thylakoid membranes.

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