 |
|
Title
|
|
Crystallographic refinement at 2.3 A resolution and refined model of the photosynthetic reaction centre from Rhodopseudomonas viridis.
|
|
|
Authors
|
|
J.Deisenhofer,
O.Epp,
I.Sinning,
H.Michel.
|
|
|
Ref.
|
|
J Mol Biol, 1995,
246,
429-457.
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
The atomic model of the photosynthetic reaction centre from the purple bacterium
Rhodopseudomonas viridis has been refined to an R-value of 0.193 at 2.3 A
resolution. The refined model contains 10,288 non-hydrogen atoms; 10,045 of
these have well defined electron density. A Luzzati-plot indicates an average
co-ordinate error of 0.26 A. During refinement, the positions of a partially
ordered carotenoid, a unibiquinone in the partially occupied QB site, a
detergent molecule, seven putative sulphate ions, and 201 water molecules were
found. More than half of these waters are bound at interfaces between protein
subunits and therefore contribute significantly to subunit interactions. Water
molecules also play important structural and probably functional roles in the
environment of some of the cofactors. Two water molecules form hydrogen bonds to
the accessory bacteriochlorophylls and to the protein in the vicinity of the
special pair of bacteriophylls, the primary electron donor. A group of about 10
water molecules is bound near the binding site of the secondary quinone QB.
These waters are likely to participate in the transfer of protons to the doubly
reduced QB.
|
|
|
|