Protein R-phycoerythrin from marine red alga Amphiroa anceps: extraction, purification and characterization

The paper reports an efficient procedure for the extraction and purification of R-phycoerythrin (R-PE) from marine red algae Amphiroa anceps. A. anceps was extracted in 50 mM phosphate buffered saline and precipitated by (NH4)2SO4. The R-PE was isolated by ion-exchange chromatography loaded with Q-Sepharose Fast Flow, which was developed by linear ionic strength gradients. Then it was purified by gel filtration Sepharose CL-6B column chromatography. SDS-PAGE showed the presence of two major subunits with 18 kDa and 20 kDa, respectively, and a minor subunit of 30 kDa. The observations are consistent with the (αβ)6γ subunit composition characteristic of R-PE. The absorption spectrum of R-PE was characterized by three absorbance maxima at 563, 538 and 495 nm, respectively, and the fluorescence emission spectrum at room temperature was 580 nm. Furthermore, R-PE showed good stability between pH 3.5 and 9.5. However, under oxidative conditions R-PE lost its shining. The results indicate that using ion-exchange chromatography with Q-Sepharose and gel filtration Sepharose CL-6B chromatography, R-PE can be purified on large scale from the red alga A. anceps.