The Quinone Acceptor A1in Photosystem I:  Binding Site, and Comparison to QAin Purple Bacteria Reaction Centers

1998 ◽  
Vol 102 (42) ◽  
pp. 8278-8287 ◽  
Author(s):  
Andreas Kamlowski ◽  
Brigitte Altenberg-Greulich ◽  
Arthur van der Est ◽  
Stephan G. Zech ◽  
Robert Bittl ◽  
...  
Keyword(s):  
Binding Site ◽  
Photosystem I ◽  
Purple Bacteria ◽  
Reaction Centers ◽  
Quinone Acceptor

scholarly journals Calculated Molecular Structures Of Anion Ubiquinone In The Gas Phase, In Solvents And In The Qa Binding Site Of Purple Bacteria Reaction Centers

2012 ◽  
Vol 3 ◽  
pp. 18-23
Author(s):  
Hari Prasad Lamichhane
Keyword(s):  
Binding Site ◽  
Gas Phase ◽  
Anion Radical ◽  
Purple Bacteria ◽  
Polarizable Continuum Model ◽  
Reaction Centers ◽  
Molecular Structures ◽  
Carbonyl Groups ◽  
Methoxy Groups ◽  
Polarizable Continuum

Structural properties of ubiquinone one anion radical (UQ1-) are studied in the gas phase and in QA binding site of purple bacteria reaction center using Gaussian 03. Polarizable continuum model (PCM) and Our own N-layered quantum mechanics + molecular mechanics (ONIOM) methods have been used to optimize the UQ1- molecule in solvent and in the QA binding site of purple bacteria Rhodobactor sphaeroides reaction centers. The UQ1- molecule exist four equivalent conformations of methoxy groups in the gas phase and solvents. However, all four conformations reduce to one in the QA binding site of the purple bacteria reaction centers. Both carbonyl (C=O) bond lengths are similar in all four conformations in the gas phase and in solvents. However, C4=O bond is slightly longer than C1=O bond in the QA binding site. This result infers that QA binding site impacts asymmetric interaction on the carbonyl groups of the quinone molecule.The Himalayan PhysicsVol. 3, No. 32012Page : 18-23

scholarly journals Theoretical Assessment of Hinge-Type Models for Electron Donors in Reaction Centers of Photosystems I and II as Well as of Purple Bacteria

2020 ◽  
Author(s):  
Denis Artiukhin ◽  
Patrick Eschenbach ◽  
Jörg Matysik ◽  
Johannes Neugebauer
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Purple Bacteria ◽  
High Sensitivity ◽  
Reaction Centers ◽  
Electron Donors ◽  
Molecular Systems ◽  
Density Distributions ◽  
Theoretical Assessment ◽  
Spin Densities

Hinge-type molecular models for electron donors in reaction centers of Photosystem I, II, and purple bacteria were investigated using a two-state computational approach based on Frozen-Density Embedding. This methodology, dubbed FDE-diab, is known to avoid consequences of the self-interaction error as far as intermolecular phenomena are concerned, which allows to predict qualitatively correct spin densities for large bio-molecular systems. The calculated spin density distributions are in a good agreement with available experimental results and demonstrated a very high sensitivity to changes in relative orientiation of co-factors and amino-acid protonation states. This allows to validate the previously proposed hinge-type models and make predictions on protonation states of axial histidine molecules. Contrary to the reaction centers in Photosystem I and purple bacteria, the axial histidines from Photosystem II were found to be deprotonated. This fact might shed some light on remarkable properties of Photosystem II reaction centers.

scholarly journals Theoretical Assessment of Hinge-Type Models for Electron Donors in Reaction Centers of Photosystems I and II as Well as of Purple Bacteria

2020 ◽  
Author(s):  
Denis Artiukhin ◽  
Patrick Eschenbach ◽  
Jörg Matysik ◽  
Johannes Neugebauer
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Purple Bacteria ◽  
High Sensitivity ◽  
Reaction Centers ◽  
Electron Donors ◽  
Molecular Systems ◽  
Density Distributions ◽  
Theoretical Assessment ◽  
Spin Densities

Hinge-type molecular models for electron donors in reaction centers of Photosystem I, II, and purple bacteria were investigated using a two-state computational approach based on Frozen-Density Embedding. This methodology, dubbed FDE-diab, is known to avoid consequences of the self-interaction error as far as intermolecular phenomena are concerned, which allows to predict qualitatively correct spin densities for large bio-molecular systems. The calculated spin density distributions are in a good agreement with available experimental results and demonstrated a very high sensitivity to changes in relative orientiation of co-factors and amino-acid protonation states. This allows to validate the previously proposed hinge-type models and make predictions on protonation states of axial histidine molecules. Contrary to the reaction centers in Photosystem I and purple bacteria, the axial histidines from Photosystem II were found to be deprotonated. This fact might shed some light on remarkable properties of Photosystem II reaction centers.

Structural Role of Carotenoids in Photosynthetic Membranes

1996 ◽  
Vol 51 (11-12) ◽  
pp. 763-771 ◽  
Author(s):  
Andrey A Moskalenko ◽  
Navassard V Karapetyan
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Purple Bacteria ◽  
Reaction Centers ◽  
Structural Components ◽  
Light Harvesting Complexes ◽  
Photosynthetic Membranes

Besides the light-harvesting and protecting role, carotenoids are also instrumental as structural components for the assembly of light-harvesting complexes in purple bacteria and green plants, as well as for the formation of photosystem II complex. Carotenoids stabilize those pigm ent-protein complexes, but have no effect on the form ation of the reaction centers of purple bacteria and photosystem I of plants.

scholarly journals Reaction Centers of Purple Bacteria with Modified Chromophores

1988 ◽  
pp. 101-111 ◽  
Author(s):  
H. Scheer ◽  
D. Beese ◽  
R. Steiner ◽  
A. Angerhofer
Keyword(s):  
Purple Bacteria ◽  
Reaction Centers

Stabilization of the electron in the quinone acceptor part of the Rhodobacter sphaeroides reaction centers

BIOPHYSICS ◽  
2008 ◽  
Vol 53 (4) ◽  
pp. 291-295
Author(s):  
P. P. Knox ◽  
P. M. Krasilnikov ◽  
P. A. Mamonov ◽  
N. Kh. Seifullina ◽  
A. F. Uchoa ◽  
...  
Keyword(s):  
Rhodobacter Sphaeroides ◽  
Reaction Centers ◽  
Quinone Acceptor
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