PIGMENT-PROTEIN COMPLEXES IN A MARINE SPECIES OF XANTHOPHYTA

A water-soluble photosynthetic light-harvesting complex was being isolated from a marine picoalga strain PP983 of Xanthophyta, grown under mass culture conditions. A crude preparation of this complex was obtained as a brick red supernatant by sonication of a whole cell suspension in 0 1 mol L-1 Tris buffer pH8.4 followed by high speed centrifugation. The extract was purified by 30% and 45%(NH4)2SO4 fractionation and Sephadex G-100 chromatography. The pigment-protein complex is characterized by its absorption spectrum having main absorption maxima at 458nm, 482nm and 670nm, and another maximum at approximately 300 nm by using a SHIMADZU UV-1601 spectrophotometer to scan room spectra ranging from 300 to 750nm. The results of absorption spectra showed that the complex have the characteristics of the peridinin-chlorophyll a-protein complex(PCP) of dinoflagellates. Chromophore analysis, by spectral analysis of extracts and polyamide thin-layer chromatography confirmed the presence of peridinin and chlorophyll a in the complex. Therefore, the peak at 458nm and 670 nm corresponds to Soret band and α band of chlorophyll a respectively, and the maximum at 482 nm is due to peridinin present in the complex. The chromoprotein has a molecular weight of about 154,200 and shows that a peridinin:chlorophyll a:protein ratio is close to 16:2:5 according to spectrophotometric analyses of chromophore content. The result indicated that the peridinin-chlorophyll a-protein complex presumably functions in vivo as photosynthetic lightharvesting pigments.