Chorophyll a' / P-700 and pheophytin a / P-680 stoichiometries in higher plants and cyanobacteria determined by HPLC analysis
1988
Kobayashi, M. | Watanabe, T. | Nakazato, M. | Ikegami, I. | Hiyama, T. | Matsunaga, T. | Murata, N.
The chlorophyll (Chl) a' and pheophytin (Pheo) a contents in photosynthetic organs have been reinvestigated by means of silica HPLC. Previously reported data (Watanabe, T. et al. (1985) BBA 807, 110-117 and FEBS Lett. 191, 252-256) were found to contain errors from two sources: slight epimerization and phenophytinization of Chl a during pigment extraction and PS I particle preparation, and an accidental overlap of a Chl a alteration product (meso-chlorinated Chl a) with Chl a' on the HPLC trace. The pigment molar ratios determined with the improved extraction / HPLC procedure were Chl a / Chl a' approximately equal 460 and Chl a / Pheo approximately equal 120 in more than 100 samples from 13 different higher plants, and Chl a / Chl a' approximately equal 125 and Chl a / Pheo a approximately equal 100 in three cyanobacteria. These values, when combined wilth the PS I particle composition (Chl a' / P-700 = 1) and the widely accepted molar ratio Pheo a / P-680 of 2, yield P-680 / P-700 = 1.9 +/- 0.5 and 0.65 +/- 0.20 as reaction center stoichiometris in higher plants and cyanobacteria, respectively. The present results correspond well with the recently published Chl a / reaction center stoichiometry data acquired by (photo-)redox titrations of key components.
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