PS_1.3 Redox Potential:

Redox (Oxidation/Reduction) Potential is a measure of a tendency, either gain or lose electrons when it is subject with a new species. A chemical reaction in which electrons are transferred from one atom (which is oxidized) to another atom (which is reduced).

The Redox Potential is a measure (in Volts) of the affinity of a substance for electrons, it is electro-negativity, compared with hydrogen (which is set at 0). Substances are more strongly electronegative than (i.e. capable of oxidizing) hydrogen have positive redox potentials. Substances are less electronegative than (i.e. capable of reducing) hydrogen have negative redox potentials.

Oxidations and Reduction always go together. They are called Redox Reactions. Oxidation means losing of electrons. Reduction means receiving (or gaining) of electrons.

Fig: Oxidation & Reduction

This figure is a favorite mnemonic to understand the Redox potential and also very descriptive and informative of this process, I hope so[1].

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PS_2.2 Highlights in Photosynthesis Research:

1771	: Joseph Priestley, England	: Discovers that plants can "purify" air that has been "burned out" by a candle.
1779	: Jan Ingenhousz, The  Netherlands	: Demonstrates that the plant in Priestley's experiment is dependent on light and its green parts.
1782 - 1804		: Several researchers show that carbon dioxide and water are stored as organic matter by plants.
1845	: Robert Mayer, Germany	: Points out that plants store solar energy in organic matter.
Ca 1915	: Richard Willstätter, Germany	: Suggests that chlorophyll plays an active role in plants (Nobel Prize in 1915).
Ca 1930	: Cornelis van Niel, USA	: Proposes that photosynthesis is based on oxidation-reduction reactions and that the primary reaction is a photolysis of water followed by oxygen evolution.
1932	: Robert Emerson and William Arnold, USA	: Conclude that several hundred chlorophyll molecules cooperate in photosynthesis.
1939	: Robert Hill, England	: Demonstrates that photolysis of water and carbon dioxide fixation are separate processes.
1940	: Hans Fischer, Germany	: Solves the chemical structure of chlorophyll. (Nobel Prize 1930 for his investigations of hemes and chlorophyll.)
1954	: Melvin Calvin, USA	: (Nobel Prize 1961) and coworkers unravel the reactions of carbon dioxide fixation (Nobel Prize in 1961).
1954	: Daniel Arnon, USA	: Discovers light-dependent synthesis of ATP (photophosphorylation).
1960 - 1961	: Robert Hill and Fay Bendall, England, and independently Louis  Duysens, The Netherlands	: Show how two separate photosystems cooperate in plants.
1968	: William Parson, USA	: Confirms Duysens' hypothesis (1956) that chlorophyll is oxidized in the primary reaction of photosynthesis.
1984	: Johann Deisenhofer, Robert Huber and Hartmut Michel	: The Federal Republic of Germany, solve the structure of a photosynthetic reaction center from a bacterium (Nobel Prize in 1988).
1992	: Rudolph A. Marcus	: For the  contributions to the theory of electron transfer reactions in chemical systems (Nobel Prize in 1992).

Source: Nobel Academy

PS_1. 1AIJ - Brief introduction:

(PHOTOSYNTHETIC REACTION CENTER FROM  RHODOBACTER   SPHAEROIDES  IN THE CHARGE - NEUTRAL  $D{Q}_A{Q}_B$  STATE)

Classification: Photosynthetic Reaction Center;  

Organism: Rhodobacter Sphaeroides 

Deposited: 1997-04-18; Released: 1997-10-22

Deposited Author: Stowell, M.H.B.,  Mcphillips, T.M.,  Soltis, S.M.,  Rees, D.C.,  Abresch, E., Feher, G.

Experimental Data snapshot:

Method: X-Ray Diffraction

Resolution: $2.2 A^0$

1AIJ structural view - PyMOL

1AIJ is a 6 chain structure with sequence from Rhodobacter Sphaeroides [1]. These are represented by 3 sequence - unique entities [2].

(Rhodobacter Sphaeroides is a kind of purple bacteria; a group of bacteria that can obtain energy through photosynthesis). 

(Purple Bacteria are Proteobacteria that are Phototrophic: i.e capable of producing their own food via. Photosynthesis). 

1AIJ structural view - PyMOL

Molecule: Photosynthetic Reaction Center (L sub-unit); Chain: L, R 

Molecule: Photosynthetic Reaction Center (M sub-unit); Chain: M, S 

Molecule: Photosynthetic Reaction Center (H sub-unit); Chain: H, T

Basic information about 1AIJ

Full wwPDB X-ray structure validation Report

Photosynthetic Reaction Center - 1AIJ

PS_4.3 Journal/Books Linklist - Collection:

• MDPI - Open Access Publishing

• NCBI - National Center for Biotechnology Information

• Cell.Com - Journal Home

• Journal of Chemical Information & Modeling

• Publishing Journals, Books & Database

• IDEALS Journal Collection

• JACS - Journal of American Chemistry Society

• Science Direct - Journal

• Oxford Press - Journal

• Scolar.Com - (Anything what ever you want to search)

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Books:

- Photosynthesis Reaction Center - Johann Deisen Hofer*, James R. Norris

- The Reaction Center of Photosynthetic Bacteria Structure and Dynamics - M. Michel*, E. Beyerle (**)

- Molecular Dynamics Simulation of the primary process in the Photosynthetic Reaction Center of Rhodopseudomonas Viridis - H. Treutlein, K.Schulten, J. Deisenhafer*, H. Michel*, A. Brunger, M. Karplus

PS_5. At last - My Work:

"The truth is rarely pure and never simple !!" ~ Unknown

“Great  Things never  came From  comfort  zones.”

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Additional References:

1. Structure of electron transfer flavoprotein - ubiquinone oxidoreductase and electron transfer to the mitochondrial ubiquinone pool (pdf)

2. Structure of the photosynthetic reaction centre from Rhodobacter sphaeroides at 2.65 •A resolution: cofactors and protein-cofactor interactions (pdf)

3. Structure of the reaction center from Rhodobacter sphaeroides R-26: The cofactors* (pdf)

» Summarized the Dissertation Work: