FTIR spectroscopy shows weak symmetric hydrogen bonding of the QB carbonyl groups in Rhodobacter sphaeroides R26 reaction centres

FEBS Letters

Hoff, A.J.²  de Groot, H.J.M.³  Lugtenburg, J.³  Brudler, R.¹  Gast, P.²  Gerwert, K.¹  van Liemt, W.B.S.³ 

[1] Lehrstuhl für Biophysik, Ruhr-Universität Bochum, Postfach 102148, 44780 Bochum, Germany;Department of Biophysics, Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands;Department of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands

关键词: Bacterial reaction centre;    Ubiquinone;    Fourier transform infrared spectroscopy;    isotopic labelling;    Photosynthesis;    RC;    reaction centre;    Rb;    Rhodobacter;    P;    primary electron donor;    QA primary acceptor quinone;    QB;    secondary acceptor quinone;    UQ;    ubiquinone;    ENDOR;    electron-nuclear double resonance;    EPR;    electron paramagnetic resonance;    FTIR;    Fourier transform infra-red;    NMR;    nuclear magnetic resonance;   

DOI  :  10.1016/0014-5793(95)00805-J

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The absorption frequencies of the C = O and C = C (neutral state) and of the C̲⋯O (semiquinone state) stretching vibrations of Q_B have been assigned by FTIR spectroscopy, using native and site-specifically 1-, 2-, 3- and 4-¹³C-labelled ubiquinone-10 (UQ₁₀) reconstituted at the Q_B binding site of Rhodobacter sphaeroides R26 reaction centres. Besides the main C = O band at 1641 cm⁻¹, two smaller bands are observed at 1664 and 1651 cm⁻¹. The smaller bands at 1664 and 1651 cm⁻¹ agree in frequencies with the 1- and 4-C = O vibrations of unbound UQ₁₀, showing that a minor fraction is loosely and symmetrically bound to the protein. The larger band at 1641 cm⁻¹ indicates symmetric H-bonding of the 1- and 4-C = O groups for the layer fraction of UQ₁₀ but much weaker interaction as for the 4-C = O group of Q_A The FTIR experiments show that different C = O protein interactions contribute to the factors determining the different functions of UQ₁₀ at the Q_A and the Q_B binding sites.

【 授权许可】

Unknown