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Sunlight is the ultimate energy source for the earth, and photosynthesis is essential for maintaining almost all life. The primary process of photosynthesis is initiated by photoexcitation and subsequent charge separation at the socalled reaction center (RC).Oxygenic photosynthetic organisms (higher plants, algae and cyanobacteria) have two types of photosystems (PS), according to the nature of the component molecules of the electron acceptor side. 1,2 One is called PS1, possessing Fe-S centers; another is PS2, having quinones.Chlorophyll (Chl) a (Fig. 1) is an essential pigment for oxygenic photosynthesis. However, charge separation is driven by a few special chlorophyll molecules in each RC of PS1 and PS2. Upon excitation, the primary donor pigments reduce the primary acceptor pigments. The primary donors exhibit sharp absorption changes associated with transient oxidation by flash excitation; they are named P700 in PS1 and P680 in PS2, referring to the characteristic peak wavelengths of the absorbance decrease. The primary donor of PS1 has been speculated to be Chl a′, the 13 2 -epimer of Chl a (Fig. 1); 3 the primary acceptor of PS2 is a metal-free Chl a, namely, Phe a ( Fig. 1). 4 In contrast, both the primary donor of PS2 and the primary acceptor of PS1 are apparently normal-type Chl, namely, Chl a.In 1996, a novel oxygenic alga Acaryochloris marina was isolated from a species of colonial ascidians. 5 Although in all previously known organisms capable of oxygenic photosynthesis the dominating chlorophyll is Chl a, the dominating pigment of A. marina is Chl d (Fig. 1). The Chl a content in A. marina is very low, ca. 3% of the Chl d content. [5][6][7] Phycobiliproteins (PBP) are present as antenna in relatively small amounts only. 8,9 Such an unusual pigment composition results in a unique constitution of the photosystems of A. marina. Because isolated PS1 particles showed a flash-induced absorbance loss maximum at ca. 740 nm, the primary donor of PS1 was named P740, 10 corresponding to P700 in other oxygenic photosynthetic organisms. P740 was assumed to consist of Chl d, and not Chl a′. 10The nature of the primary donor of PS2, P680, is still under debate, because it is hard to detect unambiguously the characteristic spectral signal. In comparison with P700 or P740, the data on P680 still remain scanty. Recently, time-resolved florescence spectroscopy in the ps and ns time range on the A. marina cells showed that a delayed fluorescence peak from PS2 was in the Chl a emission range, and not in the wavelength region of Chl d emission;11 hence, the electron donor of PS2 in A. marina was most probably identical with that of other oxygenic photosynthetic organisms, namely, P680 consisting of Chl a. In contrast, information on the primary electron acceptors of PS1 and PS2 in A. marina is so far quite limited.In this paper, we report on the results of a pigment composition analysis of A. marina cells by silica normal-phase HPLC. Chl d′ and Phe a were detected as minor pigments in

Ortho‐, meta‐, and para‐phenylenediamines were polymerized using hydrogen peroxide as an oxidant and horseradish peroxidase as a catalyst in mixed solvents of 1,4‐dioxane and water. The yield of the polymers was strongly dependent on solvent composition, and maximum yields were obtained at 15–30% 1,4‐dioxane. The analysis of circular dichroic spectra of the enzyme suggested that enzyme structure was significantly modified at high 1,4‐dioxane contents, which may be responsible for the decrease of catalytic activity of the enzyme. On the basis of IR and electronic spectra of the polymers, it was considered that o‐ and p‐phenylenediamine polymers retain disubstituted benzene nuclei, which suggests that the polymerization proceeded mainly via N—N coupling. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2593–2600, 1998

The major pigments of both antenna and reaction centers (RCs) are chlorophylls (Chls) in higher plants and bacteriochlorophylls (BChls) in photosynthetic bacteria. Except for the metal-free pheophytin (Pheo) a, bacteriopheophytin (BPheo) a (see Fig. 1) and BPheo b acting as primary electron acceptors in RCs 1-3 , only Mg has been known as the central metal of Chls and BChls until we recently found a novel Zn-containing BChl a in an aerobic bacterium Acidiphilium rubrum growing at low pH (ca. 3) 4 and confirmed its structure to be identical with that of BChl a esterified with phytol.