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Chlorophyll a′/P-700 and pheophytin a/P-680 stoichiometries in higher plants and cyanobacteria determined by HPLC analysis

1988; Elsevier BV; Volume: 936; Issue: 1 Linguagem: Inglês

10.1016/0005-2728(88)90254-x

1879-2650

Masami Kobayashi, Tadashi Watanabe, Masataka Nakazato, Isamu Ikegami, Tetsuo Hiyama, Tadashi Matsunaga, Norio Murata,

Plant Stress Responses and Tolerance

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 pheophytinization 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′ ÷ 460 and Chl a/Pheo a ÷ 120 in more than 100 samples from 13 different higher plants, and Chl a/Chl a′ ÷ 125 and Chl a/Pheo a ÷ 100 in three cyanobacteria. These values, when combined with 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 stoichiometries 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.