Spectral and photochemical properties of borohydride‐treated D1‐D2‐cytochrome b‐559 complex of photosystem II

FEBS Letters

Owens, Thomas G²  Shkuropatov, Anatoli Ya¹  Shuvalov, Vladimir A¹  Volshchukova, Tatyana S¹  Khatypov, Ravil A¹  Shkuropatova, Valentina A¹ 

[1] Institute of Soil Science and Photosynthesis, Russian Academy of Sciences, Pushchino, Moscow Region 142292, Russian Federation;Section of Plant Biology, Cornell University, Ithaca NY 14853, USA

关键词: Photosystem II;    D1-D2-cytochrome b-559 complex;    Pheophytin a;    Sodium borohydride;    Chemical modification;    Chl a;    chlorophyll a;    cyt;    cytochrome;    DM;    n-dodecyl-β-d-maltoside;    P680;    primary electron donor in PS II;    Pheo a;    pheophytin a;    PS II;    photosystem II;    RC;    reaction center;   

DOI  :  10.1016/S0014-5793(97)01512-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The D1-D2-cytochrome b-559 reaction center complex of photosystem II with an altered pigment composition was prepared from the original complex by treatment with sodium borohydride (BH⁻ ₄). The absorption spectra of the modified and original complexes were compared to each other and to the spectra of purified chlorophyll a and pheophytin a (Pheo a) treated with BH⁻ ₄ in methanolic solution. The results of these comparisons are consistent with the presence in the modified complex of an irreversibly reduced Pheo a molecule, most likely 13¹-deoxo-13¹-hydroxy-Pheo a, replacing one of the two native Pheo a molecules present in the original complex. Similar to the original preparation, the modified complex was capable of a steady-state photoaccumulation of Pheo⁻ and P680⁺. It is concluded that the pheophytin a molecule which undergoes borohydride reduction is not involved in the primary charge separation and seems to represent a previously postulated photochemically inactive Pheo a molecule. The Q_y and Q_x transitions of this molecule were determined to be located at 5°C at 679.5–680 nm and 542 nm, respectively.

【 授权许可】

Unknown