A routine method to determine the chlorophyll alpha, pheophytin alpha and beta-carotene contents of isolated Photosystem II reaction center complexes

The most simple way in which the stoichiometry of chlorophyll a, pheophytin a and beta-carotene in isolated Photosystem II reaction center complexes can be determined is by analysis of the spectrum of the extracted pigments in 80% acetone. We present two different calculation methods using the extinction coefficients of the purified pigments in 80% acetone at different wavelengths. One of these methods also accounts for the possible presence of chlorophyll b. The results are compared with results obtained with HPLC pigment analysis, and indicate that these methods are suitable for routine determination of the pigment stoichiometry of isolated Photosystem II reaction center complexes.