Energy Transfer in Trimeric C‐phycocyanin Studied by Picosecond Fluorescence Kinetics

The excited state kinetics of trimeric C‐phycocyanin from Mastigocladus laminosus has been measured as a function of the emission and excitation wavelength by the single‐photon timing technique with picosecond resolution and simultaneous data analysis. A fast decay component of 22 ps (C‐phycocyanin with linker peptides) and 36 ps (C‐phycocyanin lacking linker peptides) is attributed to efficient energy transfer from sensitizing to fluorescing chromophores. At long detection wavelengths the fast decay components are found to turn into a rise term. This finding further corroborates the concept of intramolecular energy transfer. Previous reports on the conformational heterogeneity of the chromophores and/or proteins in C‐phycocyanin are confirmed. Our data also provide indications for the importance of the uncoloured linker peptides for this heterogeneity.