Subunit composition and chromophore content of R-phycocyanin and allophycocyanin from Porphyra haitanensis

R-phycocyarnin (RPC) of Porphyra haitmmsis (T.J.Chang et B.F.Zheng) was chromatographed on Bio-Rex 70 column with urea solution (pH 3.0) as an eluent, and α and β two subunits were isolated.Their molecular weights were determined on SDS-PAGE at 18 400 and 20 500, respectively, while those of a and β subunits of allophycocyanin (APC) at 18 800 and 19 700, respeMively, and those of RPC and APC were at 117 000 and 122 000, respectively.
Both the molar ratio of α and β subunits of RPC and APC were 1:1, and the subunit composition was conf firmed to be(αβ)₃.
It was ascertained that in RPC a subunit contains one chromophore phycocyanobilin (PCB) and β subunit has one chromophore PCB and one phycoerythrobilin (PEB),while in APC both α and β subunits contain one PCB.