Preparation of chlorophylls and pheophytins by isocratic liquid chromatography

Watanabe, Tadashi; Hongu, Akinori; Honda, Kenichi; Nakazato, Masataka; Konno, Mitsuo; Saitoh, Sadao

doi:10.1021/ac00266a030

Cited by 177 publications

(119 citation statements)

References 34 publications

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“…A standard solution containing known amounts of authentic ␣-carotene, Chl a, Chl d, and Phe a was used for quantitative calibration. We used published molar extinction coefficients for the individual pigments (45)(46)(47). The PQ-9 content was measured by reverse-phase HPLC as described in detail elsewhere (21).…”

Section: Methodsmentioning

confidence: 99%

Identification of the special pair of photosystem II in a chlorophyll d -dominated cyanobacterium

Tomo

Okubo

Akimoto

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

125

127

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The composition of photosystem II (PSII) in the chlorophyll (Chl) d-dominated cyanobacterium Acaryochloris marina MBIC 11017 was investigated to enhance the general understanding of the energetics of the PSII reaction center. We first purified photochemically active complexes consisting of a 47-kDa Chl protein (CP47), CP43 (PcbC), D1, D2, cytochrome b 559, PsbI, and a small polypeptide. The pigment composition per two pheophytin (Phe) a molecules was 55 ؎ 7 Chl d, 3.0 ؎ 0.4 Chl a, 17 ؎ 3 ␣-carotene, and 1.4 ؎ 0.2 plastoquinone-9. The special pair was detected by a reversible absorption change at 713 nm (P713) together with a cation radical band at 842 nm. FTIR difference spectra of the specific bands of a 3-formyl group allowed assignment of the special pair. The combined results indicate that the special pair comprises a Chl d homodimer. The primary electron acceptor was shown by photoaccumulation to be Phe a, and its potential was shifted to a higher value than that in the Chl a/Phe a system. The overall energetics of PSII in the Chl d system are adjusted to changes in the redox potentials, with P713 as the special pair using a lower light energy at 713 nm. Taking into account the reported downward shift in the potential of the special pair of photosystem I (P740) in A. marina, our findings lend support to the idea that changes in photosynthetic pigments combine with a modification of the redox potentials of electron transfer components to give rise to an energetic adjustment of the total reaction system. Acaryochloris marina ͉ FTIR ͉ reaction center ͉ photosynthesis ͉ electron transfer C hlorophyll (Chl) a has a ubiquitous role as an electron donor in the photochemical reactions of oxygenic photosynthesis, in which two kinds of photosystem, namely photosystem I (PSI) and photosystem II (PSII), cooperatively drive photosynthetic electron flow from water to NADP ϩ . The reduced cofactor, NADPH, is then used for CO 2 fixation. Chl a is a key pigment that serves as an electron donor called the special pair in PSI and PSII. Acaryochloris spp. are unique cyanobacteria that differ from the majority of photosynthetic organisms by having Chl d (3-desvinyl-3-formyl Chl a) (1-4) as the major pigment (Ͼ95%); Chl a is a minor component but is never absent (5, 6). In photosynthetic organisms, changes in pigment composition affect both the function of pigments and their reaction environments, including the modified proteins that accommodate them. Photosynthetic pigments function in two roles: as lightharvesting components and as electron transfer components. Light harvesting is mainly governed by the orientation and energy levels of pigments, and, in this context, a particular excitation energy level is not an absolute precondition for function, but a relative one. On the other hand, electron transfer reactions are governed by an absolute redox potential, because the photosynthetic oxidation of water requires a very high potential, whereas reduction of NADP ϩ requires a very low potential. For this reason, it is of particul...

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Section: Methodsmentioning

confidence: 99%

Identification of the special pair of photosystem II in a chlorophyll d -dominated cyanobacterium

Tomo

Okubo

Akimoto

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

125

127

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“…The reversed phase system is described in [23]. The normal phase system is adapted from [24] (Alltech Cartridge SS150~4.6 mm, Rosil 5 Cm start conditions 100% solvent A, final conditions 40% A and 60% B, 30 min nonlinear gradient no. 7 on Waters model 660 gradient programmer; solvent A is toluene/methanol/2-propanol (100:0.3 :0.2) and solvent B is toluene/methanol/2-propanol (100 : 1.6 : 0.2).…”

Section: Published By Elseviermentioning

confidence: 99%

Modified reaction centers from Rhodobacter sphaeroides R26

Struck¹,

Scheer²

1990

FEBS Letters

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Incubation of photosynthetic reaction centers from Rhodobucter sphaeroides R26 with exogenous lY-OH-bacteriochlorophyll ar or aoo according to Scheer et al. (1987) results in the exchange of endogenous bacteriochlorophyll ar. The exchange amounts to 5 50% according to HPLC analysis, corresponding to a complete replacement of the 'monomeric' bacteriochlorophylls, Bu and Br, by exogenous pigment. The absorption spectra show small, but distinct changes in the Qx-region of the bacteriochlorophylls, and bleaching of the modified reaction centers is retained. The corresponding binding sites must be accessible from the exterior, and allow for the introduction of a polar residue at C-1P. This is supported by the observation of side reactions of the endogenous 'monomeric' bacteriochlorophylls within the reaction center pigments, e.g. epimerization and hydroxylation at C-l32.

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“…The extract was dried under a stream of argon, dissolved in toluene, and then subjected without delay to HPLC-analysis according to Watanabe et al (1984).…”

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confidence: 99%