Characterization of Peridinin-Chlorophyll α-Proteins from the Marine Dinoflagellate Ceratium furca

Abstract

C. furca, a golden-colored dinoflagellate was examined for the presence of a water-soluble form of the peridinin-chlorophyll [Chl] a-protein (PCP), the major light harvesting pigment in dinoflagellates. This chromoprotein, once found, was analyzed by gel filtration, isoelectric focusing and SDS [sodium dodecyl sulfate] polyacrylamide gel electrophoresis (SDS-PAGE). The intact PCP complex from Ceratium was isolated by molecular sieve column chromatography and in a similar manner was determined to have a MW of 34,000-37,000 daltons. The complex consisted of a protein and a chromophore containing peridinin and Chl a. The ratio of peridinin to Chl a in the complex was 4:1, as determined by quantitative TLC. SDS-PAGE indicated that the MW of the polypeptide chains thus obtained was .apprx. 16,500 daltons. These MW and pigment ratios suggested that the most reasonable stoichiometry for the PCP complex from Ceratium was 4 peridinins, 1 Chl a and a protein consisting of 2 polypeptide chains. The stoichiometry, composition and isoelectric points of the conformers of PCP from Ceratium are similar to that of PCP from another dinoflagellate, Glenodinium sp.