Purification and characterization of C-Phycocyanin from cyanobacterial species of marine and freshwater habitat

The present paper describes an efficient single step chromatographic method for purification of C-Phycocyanin from three cyanobacterial species, i.e., Spirulina sp. (freshwater), Phormidium sp. (marine water) and Lyngbya sp. (marine water). C-Phycocyanin from these cyanobacterial species was purified to homogeneity and some of their properties were investigated. The purification involves a multistep treatment of the crude extract by fractional precipitation with ammonium sulfate, followed by ion-exchange chromatography on DEAE-Sepharose CL-6B column. Pure C-Phycocyanin was finally obtained from Spirulina, Phormidium, and Lyngbya spp. with purity ratio (A620/A280) 4.42, 4.43, and 4.59, respectively, further the purity and homogeneity were confirmed by native and SDS-PAGE. The estimated molecular weights of purified C-PC from Spirulina, Phormidium, and Lyngbya spp. were 112, 131, and 81 kDa, respectively. SDS-PAGE of pure C-Phycocyanin yielded two bands corresponding to α and β subunits. The results of SDS-PAGE demonstrate the same molecular weight of β subunits (24.4 kDa) for all the three cyanobacterial species, whereas the molecular weight of the α subunit is different for all (17 kDa Spirulina sp., 19.1 kDa Phormidium sp., 15.2 kDa Lyngbya sp.). Thus, the C-Phycocyanin was characterized as (αβ)3 for Spirulina and Phormidium spp., while as (αβ)2 for Lyngbya sp.