Pigment—protein complexes of green algae: Improved methodological steps for the quantification of pigments in pigment—protein complexes derived from the green algae Chlorella and Chlamydomonas

An improved method for the determination of pigments within pigment—protein complexes (PPCS) of thylakoid membranes is presented. It comprises (a) a fast high resolution SDS — polyacrylamide gel electrophoresis (SDS ≡ sodium dodecylsulphate), (b) a new approach for the recovery of PPCs from the gel with an additional purification step and (c) a one-step separation of the chlorophylls and carotenoids by reversed-phase high performance liquid chromatography. This three-step procedure is applied to the analysis of thylakoid membranes derived from synchronized cells of the green alga Chlorella fusca, and to PPCs from Chlamydomonas reinhardii, parent strain 11/23f and the Chl- b-less mutant pg 113. The results show that a varying pattern of pigment—protein complexes exists during the life cycle in Chlorella and that there are changes in the ratio of pigments arranged in reaction centre and antenna PPCS. The pigment composition of Chlamydomonas appears to be identical with that of Chlorella; however, the pattern of PPCs is different. Thylakoids from the Chl- b-less mutant of Chlamydomonas reveal two distinct PPCs representing photosystems I and II, both enriched in Chl a and β-carotene. About 90% of the xanthophylls migrate as free pigments, indicating an improper binding of xanthophylls to the light-harvesting complex(es) within the mutant.