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Influence of the H‐subunit and Fe 2+ on electron transport from I − to Q A in Fe 2+ ‐free and/or H‐free reaction centers from Rhodobacter sphaeroides R‐26
Author(s) -
Liu Ben-li,
van Kan Paul J.M.,
Hoff Arnold J.
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80900-n
Subject(s) - electron , chemistry , physics , crystallography , atomic physics , nuclear physics
From reaction centres (RC) of Rhodobacter sphaeroides R‐26 two LM preparations with 0.90 Fe 2+ /RC (LM) and 0.10 Fe 2+ /RC (LM/dFe) were prepared. Reconstitution of LM/dFe with the H‐subunit and subsequently with Zn 2+ yielded LMH/dFe and LMH/dFe+Zn preparations, respectively. In these four samples the decay of the primary radical pair P + I − was studied by means of transient absorption spectroscopy and compared with that in native RC. In LMH/dFe the reduction of Q A by Bpheo a occurred in 5 ns, with concomitant increase in the yield of P T , the triplet state of the primary donor. In the LM/dFe, LM and LMH/dFe+Zn preparations the decay of I − had the same rate (200 ps) −1 as in native RC. Thus, neither the H‐subunit in the RC nor a divalent metal as Fe 2+ or Zn 2+ are necessary per se for fast reduction of Q A . Only demetallation in the presence of the H‐subunit slows down the reduction of Q A .