A ROUTINE METHOD TO DETERMINE THE CHLOROPHYLL-ALPHA, PHEOPHYTIN-ALPHAAND BETA-CAROTENE CONTENTS OF ISOLATED PHOTOSYSTEM-II REACTION-CENTERCOMPLEXES

The most simple way in which the stoichiometry of chlorophyll a, pheop hytin a and beta-carotene in isolated Photosystem II reaction center c omplexes can be determined is by analysis of the spectrum of the extra cted pigments in 80% acetone. We present two different calculation met hods 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 w ith results obtained with HPLC pigment analysis, and indicate that the se methods are suitable for routine determination of the pigment stoic hiometry of isolated Photosystem II reaction center complexes.