Abstract: Two phycobiliprotein conjugates PEC-APC and PEC-PC were synthesized by a heterobifunctional coupling reagent, N-sccinimidly 3-(2-pyridyldithio) propionate. The phycobiliproteins are linked by disulfide bond. The absorption and fluorescence spectra indicate that the constructure and the conformation of the biliproteins were maintained after reaction.The energy transfer phenomenon was observed from fluorescence spectra. The energy transfer efficiency from PEC to APC calculated from the fluorescence spectra is about 90%.The excited state life time of PEC emission in conjugate PEC PC was 0.86 ns, compared with 2.1 ns for free PEC, which indicated that energy transfer did occur from PEC to C-PC in conjugate PEC-PC. The energy transfer was stopped by the addition of dithiothreitol (DTT) to the solutions of the conjugates. These results further confirmed that there was energy transfer in the conjugates.

Key words: phycobiliprotein conjugate, phycoerythrocyanin, C-phycocyanin, allophycocyanin, energy transfer