Incompetence of dark-synthesized phycocyanin in excitation transfer to photosystem II chlorophyll.

When cells of Anabaena variabilis, all the phycobilin pigments of which had been newly synthesized in the dark, were excited by light absorbed in phycocyanin, the fluorescence emission spectrum showed a peak corresponding to the emission from allophycocyanin, but no emission from chlorophyll. These cells were active in photosynthesis and, when excited by light absorbed by chlorophyll, the emitted fluorescence was characteristic of photosystem II chlorophyll. This indicates that dark synthesized phycocyanin is capable of excitation transfer to allophycocyanin but not to photosystem II chlorophyll.