Preparation of highly purified C-phycoerythrin from marine cyanobacterium Pseudanabaena sp

Abstract

C-phycoerythrin was isolated and purified from marine Pseudanabaena sp. using two step chromatographic methods. Phycobiliproteins in the marine Pseudanabaena was extracted in 100 mM phosphate buffer (pH 7.2) and precipitated by salting out. The precipitated C-phycoerythrin was purified by gel filtration with Sephadex G-150, and then it was purified by ion exchange chromatography on DEAE cellulose, which was developed by linear ionic strength gradients. Purified phycoerythrin showed absorption maxima at 568 and 541 nm, and displayed a fluorescence maximum at 578 nm. The absorbance ratio A₅₆₈/A₂₈₀, a criterion for purity (purity ratio) achieved was 6.86. It showed a single band on examination by polyacrylamide gel electrophoresis (PAGE). The polypeptide analysis of the purified C-phycoerythrin by SDS-PAGE demonstrated that it contained two chromophore-carrying subunits. The yield of purified C-phycoerythrin obtained was 13.6 mg/g of the cell dry weight with 47% of yield. Obtaining highly pure C-phycoerythrin allows one to evaluate its fluorescence properties for future applications in biochemical and biomedical research.