Bicarbonate binding to the water‐oxidizing complex in the photosystem II. A Fourier transform infrared spectroscopy study

FEBS Letters

Ibarra, J.V³  Yruela, I¹  Klimov, V.V²  Allakhverdiev, S.I¹ 

[1] Estación Experimental Aula Dei, Consejo Superior de Investigaciones Cientı́ficas (C.S.I.C.), Apdo. 202, 50080 Zaragoza, Spain;Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushchino, Moscow Region 142292, Russia;Instituto de Carboquı́mica, Consejo Superior de Investigaciones Cientı́ficas (C.S.I.C.), Poeta Luciano Gracia, 5, 50015 Zaragoza, Spain

关键词: Photosystem II;    Bicarbonate;    Donor side;    Fourier transform;    Infrared spectroscopy;    Chl;    chlorophyll;    D1;    polypeptide of PSII reaction center;    DCBQ;    2;    6-dichlorobenzoquinone;    FT-IR;    Fourier transform infrared spectroscopy;    MES;    2-(N-morpholino)ethanesulfonic acid;    OEC;    oxygen-evolving complex;    Pheo;    pheophytin;    the primary electron acceptor;    P680;    the primary electron donor;    PSII;    photosystem II;    QA and QB;    primary and secondary plastoquinone electron acceptors of PSII;    RC;    reaction center;    WOC;    water-oxidizing complex;   

DOI  :  10.1016/S0014-5793(98)00271-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The light-induced Fourier transform infrared difference (FT-IR) spectrum originating from the donor side of O₂-evolving photosystem (PS) II was obtained in non-depleted and CO₂-depleted PSII membrane preparations. The observed spectrum free of contributions from the acceptor side signals was achieved by employing 2 mM/18 mM ferri-/ferrocyanide as a redox couple. This spectrum showed main positive bands at 1589 and 1365 cm⁻¹ and negative bands at 1560, 1541, 1522 and 1507 cm⁻¹. CO-depleted PSII preparations showed a quite different spectrum. The main positive and negative bands disappeared after depletion of bicarbonate. The addition of bicarbonate partially restored those bands again. Comparison between difference FT-IR spectra of untreated and bicarbonate-depleted PSII membranes indicated that the positive bands at 1589 and 1365 cm⁻¹ can be assigned to COO⁻ stretching modes from bicarbonate. The higher frequency corresponds to u_as (COO⁻) and the lower frequency to u_s (COO⁻). ¹³C-Labeling FT-IR measurements confirmed these findings and also suggested that the negative band at 1560 cm⁻¹ can be ascribed to u_as (COO⁻). The data are discussed in the framework of the suggestion that bicarbonate can be a ligand to the Mn-containing water-oxidizing complex of PSII.

【 授权许可】

Unknown