Structural Studies of a Phycobilisome

Phycobilisomes are protein complexes present in cyanobacteria and red algae; they are involved in light harvesting and conduction of light and the aim of this study has been to understand the high efficiency observed in these processes The structure of the phycobilisome from an eukaryotic algae Gracilaria chilensis was studied by biochemical methods in order to obtain intact phycobilisomes and to obtain their phycobiliprotein components, phycoerythrin, phycocyanin and allophycocyanin. The structure of phycobilisomes has been studies by electron microscopy and electrophoresis and by theoretical methods; the structure of phycobiliproteins has been studied by protein crystallography and because they are chromophorylated, their properties also were studied by absorption and emission spectroscopy. We have also built a theoretical docking model for an antenna formed by two units of phycoerythrin and two units of phycocyanin. This model was used to obtain the kT for the transfer in resonance of the light; the pathway of the light was calculated through the antenna. An evaluation of the model was performed by comparison with the electron microscopy images. The effect the protein environment on the spectroscopic properties of the chromophoric groups was also considered and analysed. FONDECYT 108.0267.