Evaluation of multiple purification strategies and characterization of R-phycoerythrin from two species of red seaweed, Furcellaria lumbricalis and Schizymenia valentinae

R-phycoerythrin (R-PE) is a prospective natural red colorant present in red seaweed and consists of three major subunits α , β, and γ. This study aimed to investigate the outcome of intensity of R-PE subunits obtained from different purification strategies of the two red seaweed species, Furcellaria lumbricalis and Schizymenia valentinae comb. nov . R-PE was purified by i) multi-step ammonium sulphate precipitation, ii) membrane filtration , iii) anion exchange chromatography , and iv) a combination of multi-step ammonium sulphate precipitation followed by anion exchange chromatography . The characterization of purified R-PE was carried out by spectrophotometric analysis, SDS-PAGE, 3D fluorescence scan and mass spectrometry . The increased purity index and wider excitation and emission wavelengths reflected the improved purification of R-PE from both species of red seaweed relative to the crude extracts . The MS study identified peptides from other phycobiliproteins such as phycocyanin , allophycocyanin , and RuBisCO after membrane filtration . After membrane filtration, the α, β, γ subunits of R-PE, as well as phycocyanin , allophycocyanin , and RuBisCO displayed higher intensities in the purified R-PE from S. valentinae compared to F. lumbricalis , although the latter exhibited a more pronounced colour. The same was the case for samples purified by ammonium sulphate precipitation. The highest purity index was achieved after multi-step ammonium sulphate precipitation followed by anion exchange chromatography of R-PE from F. lumbricalis , which permits its utilization in food applications, although minor amounts of phycocyanin and allophycocyanin , were detected. In conclusion, separation of photosynthetic proteins was incomplete for all purification strategies.