Adenine Nucleotide Inhibition of Phosphorylation of the Light-Harvesting Chlorophyll a/b-Protein Complex

The effects of ADP, AMP and cyclic AMP on the ATP-dependent phosphorylation of the light-harvesting chlorophyll a/6-protein complex by the thylakoid protein kinase and on the associated state I-state II transition are examined. ADP and cyclic AMP significantly inhibit phosphorylation of the light-harvesting chlorophyll a / b -protein complex at 100 μM and 5 μM concentrations, respectively. This suggests the possibility of adenine nucleotide control of the kinase and the associated energy distribution between photosystems I and II.