Modified reaction centers from Rhodobacter sphaeroides R26

FEBS Letters

Cmiel, E.¹  Struck, A.²  Katheder, I.²  Scheer, H.² 

[1] Institut für Physikalische Chemie, Technische Universität München, Lichtenbergstr. 4, D-8046 Garching, FRG;Botanisches Institut, Universität, Menzinger Str. 67, D-8000 München 19, FRG

关键词: Photosynthesis;    Rhodobacter sphaeroides;    Reaction center;    Pigment modification;    Pigment exchange;    Chlorophyll;    Bacteriochlorophyll a;    [3-vinyl]-132-hydroxy-bacteriochlorophyll a;    [3-(α-hydroxyethyl)]-132-hydroxy-bacteriochlorophyll a;    Chromatography;    Circular dichroism;    BChl;    bacteriochlorophyll a;    BPhe;    bacteriopheophytin a;    RC;    reaction centers;    Rb.;    Rhodobacter;    Cd;    circular dichroism;    P;    primary donor;    B;    monomeric BChl;    H;    BPhe in RC. The subscripts ‘A’ and ‘B’ refer to the active (‘L’) and inactive branch (‘M’);    respectively;    of the electron transport chain;   

DOI  :  10.1016/0014-5793(90)81003-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Monomeric bacteriochlorophylls B_A and B_B in photosynthetic reaction centers from Rhodobacter sphaeroides R26 were exchanged with (13²-hydroxy-) bacteriochlorophylls containing a 3-vinyl- or 3-(α-hydroxyethyl)-substituent instead of the 3-acetyl group. The corresponding binding sites must be tolerant to the introduction of the polar residue at C-13² and modifications of the 3-acetyl group. According to HPLC analysis, the exchange with both pigments amounts to ≦ 50% of the total BChl contained in the complex, corresponding to ≦ 100% of the monomeric BChl aB_A,B. The absorption spectra show significant changes in the Q_x and Q_y-region of the monomeric bacteriochlorophylls. By contrast, the absorption of the primary donor (P870) and reversible photobleaching is retained. The circular dichroism is also unchanged in the 870 nm region. The positive cd band located at around 800 nm in native reaction centers, shifts with the (blue-shifted) Q_y absorption(s) of B_A and/or B_B, whereas the position of the negative one remains nearly unaffected. The data indicate that the latter is the upper excitonic band of the primary donor, and that there is little interaction of the monomeric B_A/B_B with the primary donor.

【 授权许可】

Unknown