Efficient purification and characterization of high-purity phycoerythrin 545 from Rhodomonas sp.

Abstract Cryptomonad phycoerythrin 545 is an important type of phycobiliprotein in basic research and technological innovations. Herein, we report a minimalistic hydrophobic chromatography method for its purification. High purity was achieved, with a purity ratio (A545/A280) of 13.66 and a recovery ratio of 78.63%. Following SDS-PAGE, Coomassie Brilliant Blue staining and Zn2+-enhanced UV fluorescence autoradiography revealed three bands at 9 kDa, 10 kDa, and 20 kDa, corresponding to α1, α2 and β subunits. Multiple spectral characteristics were analysed to ensure that optical activity was consistent with that of the natural protein. Absorption and fluorescence spectroscopies of purified phycoerythrin 545 displayed a strong absorption peak at 545 nm and a shoulder peak at 564 nm, and a fluorescence emission peak of at 587 nm, which confirmed unchanged energy transfer properties, and structural and functional integrity was verified by circular dichroism spectroscopy. Compared with published purification methods, this new purification protocol replaces two-step ammonium sulphate fractionation, dialysis, and size exclusion chromatography with a single chromatography step, thereby reducing the cost of large-scale kilogram-level commercial production.