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Química Bioinorganic básica de Manganeso en todoa fotosíntesis
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Los Colores de Vida
CURSO QUÍMICA BIOINORGÁNICA
UNAM Octobre 24/29, 2012 PETER M.H. KRONECK, Lab 212
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Artículos que introducenR.R. Crichton (2008)
Biological Inorganic Chemistry (chapter 16). Elsevier.
C.F Yocum, V.L Pecoraro (1999)
Current Opinion in Chemical Biology, 3,182-l 87Recent advances in the understanding of
the biological chemistry of manganese
A.J. Wu , J.E. Penner-Hahn, V.L. Pecoraro (2004)
Chemical Reviews, 104, 908-938. Structural, Spectroscopic, and Reactivity Models for the
Manganese Catalases
J.P. McEvoy, G.W. Brudvig (2006)
Chemical Reviews, 106, 4455-4483. Water-Splitting Chemistry of Photosystem II
T. M Iverson (2006)
Current Opinion in Chemical Biology, 10, 91 – 100. Evolution and unique bioenergetic
mechanisms in oxygenic photosynthesis
J. Barber (2006)
Biochemical Society Transactions, 34, 619-631. Photosystem II: an enzyme of global
significance
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookps.html
http://www.phschool.com/science/biology_place/biocoach/photosynth/overview.html 2
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Repetición: ROS = Reactive Oxygen SpeciesEspecies de Oxígeno reactivas
ss
ss*
s p*
s p
p*
p
3S+
O2
O•2-
H2O2
OH•+H2O
2H2O
-0.33V
+0.94V
+0.38V
+2.31V
E‘o vs NHE, pH 7.25
112 pm
133 pm
149 pm1554 cm-1
1145 cm-1
842 cm-1
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Conservación de la energía de hoy: Reducción de O2 a H2OGente es Aerobes
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Los elementos de vidawww.webelements.com
Abundancia en el cuerpo (75 kg)Ca: 1.2 kgK: 150 gNa: 70 gMg: 20-30 g
Fe: 4-7 gZn: 2-3 gCu: 70-100 mg
Mn: 10-12 mg
S: 140 gP: 780 g
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn
Ga Ge As Se Br Kr
Rb Sr Y Zr
Nb Mo Tc Ru Rh Pd Ag
Cd In Sn Sb Te I Xe
Cs Ba La Hf Ta W Re Os Ir Pt Au
Hg Tl Pb Bi Po At Rn
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Metales de transición - Funciones BiológicasNa Charge Carrier, Osmolysis/equilibrium
K Charge Carrier, Osmolysis/equilibrium
Mg Structure, ATP/ThDP Binding, Photosynthesis,...
Ca Structure, Signaling, Charge Carrier
V Nitrogen Fixation, Oxidases, O2 Carrier
Cr Unknow n! (glucose metabol ism ??? )
Mo Nitrogen Fixation, Oxidoreductase, O-TransferW Oxidoreductases, Acetylene Hydratase
Mn REDOX/ACID-BASE CATALYSISPhotosynthesis, Oxidases, Structure,...
Fe Oxidoreductase, O2
Transport + Activation,e--Transfer,...
Co Oxidoreductase, Vitamin B12 (Alkyl Group Transfer)
Ni Hydrogenase, CO Dehydrogenase, Hydrolases, Urease
Cu Oxidoreductases, O2 Transport, e- -Transfer
Zn Structure, Hydrolases, Acid-Base Catalysis...
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Estados de oxidación de Metales de TransiciónNa Na(I)
K K(I)
Mg Mg(II)
Ca Ca(II)
V V(V)=(d0), V(IV)=(d1), V(III)=(d2)
Cr Cr(III)=(d3),Cr(IV)=(d2),Cr(V)=(d1)
Mo Mo(III)=(d3),Mo(IV)=(d2),Mo(V)=(d1), Mo(VI)=(d0)
W W(IV)=(d2) ,W(V) =(d1), W(VI)=(d0)
Mn Mn(IV)=(d3), Mn(III)=(d4), Mn(II) =(d5)
Fe Fe(V)=(d3), Fe(IV)=(d4),Fe(III)=(d5),Fe(II)=(d6), Fe(I)?=(d7)
Co Co(III)=(d6), Co(II)=(d7), Co(I)=(d8)
Ni Ni(III)=(d7), Ni(II)=(d8), Ni(I)=(d9)
Cu Cu(III)=(d8), Cu(II)=(d9), Cu(I)=(d10)
Zn Zn(II) =(d10) 7
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Mn Biochemistry R.R. Crichton, Chap. 16
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The importance of Mn for living organisms is considerable:
(i) the tetranuclear Mn cluster involved in O2 production in photosynthetic plants, algae and cyanobacteria
(ii) mammalian enzymes, arginase and mitochondrial superoxide dismutase.(iii)Most of Mn biochemistry can be explained by its redox activity, and by
its analogy to Mg2+.
In contrast to other redox active metals (Fe) is that Mn is less reducing thanFe under most biological conditions; Fe3+ is stable relative to Fe2+, Mn2+ relative to Mn3+ (Why ?). Two important consequences of this redoxchemistry are that Mn2+ can participate in useful redox catalysis on manysimilar substrates to Fe3+, whereas the higher redox potential of Mn2+ makes
free Mn2+ harmless under conditions where free Fe2+ would producehydroxyl radicals. Cells (notably bacterial cells) can tolerate very highcytoplasmic concentrations of Mn2+ with no negative consequences; this iscertainly not the case with redox metal ions like Fe and Cu.
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Bioquímica de Mn R.R. Crichton, Chap. 16
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La importancia de Mn para organismos vivos es considerable:(i) el Mn tetranuclear cluster que está implicado en la producción de oxígeno enfábricas fotosintéticas, algas y cyanobacteria(ii) enzimas mamíferas como arginase y superóxido mitochondrial dismutase.(iii) la mayor parte de la bioquímica de Mn puede ser explicada por su actividadredox, y en otro por su analogía con Mg2+.
En contraste con otros metales activos redox (Fe) es que Mn tiene el potencialmenos que reduce que Fe en la mayor parte de condiciones biológicas; Fe3+ esestable con relación a Fe2+, Mn2+ con relación a Mn3+ (Por qué ?). Dosconsecuencias importantes de esta química redox son que Mn2+ puede
participar en la catálisis redox útil en muchos substrates similares a Fe3+
,mientras que más alto redox potencial de Mn2+ hace Mn2+ libre inocuo encondiciones donde liberado Fe2+ produciría a radicales hydroxyl. Las células(notablemente células bacterianas) pueden tolerar concentracionescitoplásmicas muy altas de Mn2+ sin consecuencias negativas; esto no es
seguramente el caso con iones metálicos redox como Fe y Cu.
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Mn Biochemistry R.R. Crichton, Chap. 16
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Mn is the cofactor for superoxide dismutases, catalases and some peroxidases. These enzymes are all used for the detoxification ofROS.
An important property of Mn in its (2+)-oxidation state, which hasimportant consequences, is that is a close but not exact surrogate ofMg2+. Mn2+ with its relatively similar ionic radius can readilyexchange with Mg2+ in most structural environments, and exhibitsmuch of the labile, octahedral coordination chemistry. However, it can
more easily accommodate the distortions in coordination geometry in progressing from the substrate-bound to the transition state and to the bound product. Consequently, Mn2+ in the active site of a Mg2+-enzyme often results in improved enzyme efficacy.
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Mn Biochemistry R.R. Crichton, Chap. 16
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Mn es el cofactor para el superóxido dismutases, catalases y algún peroxidases. Estas enzimas son todos usadas para el detoxification deROS.Una propiedad importante de Mn en su (2+) estado de oxidación, que
tiene consecuencias importantes, es un final, pero no sustituto exactode Mg2+. Mn2+ con su radio iónico relativamente similar puedecambiar fácilmente con Mg2+ en la mayor parte de ambientesestructurales, y expone la mayor parte de los labile, octahedralquímica de coordinación. Sin embargo, esto puede acomodar más
fácilmente la deformación en la geometría de coordinación en la progresión del substrate-ligado al estado de transición y al productoatado. Por consiguiente, Mn2+ con el sitio activo de un Mg2+-enzyme amenudo causa la eficacia de enzima mejorada.
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Estimated evolution of atmospheric O2The red and green lines represent the range of the estimates: stage1: 3.85 – 2.45 Gyr (Ga),stage2: 2.45 – 1.85 Ga, stage3: 1.85 – 0.85 Ga, stage4: 0.85 – 0.54Ga, stage5: 0.54 Ga – present
www.globalchange.umich.edu/globalchange1/current/lectures/Perry_Samson_lectures/evolution_atm/index.html
H.D. Holland (2006), Phil. Trans. R. Soc. B, 361, 903-915
Formas de Vida – De Anaerobio a Aerobiocondiciones anóxicas (-O2) contra condiciones óxicas (+O2)
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Activación de O2 – Tipos de Reacción
• Reversible binding of O2 – Myoglobin, Hemoglobin (Fe), Hemocyanin(Cu-Cu)
• O2.- dismutation – Superoxide Dismutase (Mn, Fe, Ni, Cu, Zn)O2.- + O2.- +2H+ → O2 + H2O2
•
H2O2 decomposition – Catalase (Mn, heme-Fe)2 H2O2 → 2 H2O + O2• Oxygenases (Mn, Fe, Cu, Cytochrome P450)
R-H + O2 + NADPH + H+ → R -OH + H2O + NADP+
• Oxidases (2-electron reduction to H2O2; Fe, Cu)
O2 + 2e- +2H+ → H2O2 (focus on Cu enzyme Galactose Oxidase)• Oxidases (4-electron reduction to H2O; heme-Fe, Cu)
O2 + 4e- +4H+ → 2 H2O (focus on Cu enzyme Ascorbic Acid Oxidaseand Fe,Cu enzyme Cytochrome c Oxidase)
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No proteína Ligantes
Ligand pKa Acid/base H2O/OH
-,O2- 14,~34
HCO3-/CO3
2- 10.3
HPO42-/PO4
3- 12.7
H3CCOO-/H3CCOOH 4.7
HO2- /H2O2 11.6
NH3 /NH4+ 9.3
N3-
/N3H
4.8F-, Cl- Br -, I-/XH 3.5, -7, -9, -11
Neutral O2, CO, NO, RNC
Mn+ O
H
H -
+
+14
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Modulación de acidez (pK a)
H2O + Mn+ HO- -Mn+-H+
+H+
Metal pKa
noneCa2+
Mn2+Cu2+
Zn2+
14.013.4
11.1 10.7
10.0
4 orders ofmagnitude !
Mn+ O H
H
-
+
+15
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Control cinético
[Mn+(H2O)m]-H2O
+H2O
[Mn+(H2O)m-1]
Metal k (s-1)
K+Ca2+
Mn2+Fe2+
Ni2+
1x1093x108
2x1074x106
4x104
15 orders ofmagnitude!
Fe3+ 2x102
Co2+ 3x106
Co3+
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Velocidades de cambio acuáticosM. Eigen, Nobel Prize Lecture 1967
Expresado como vida de complejosÚtil para mirar la reactividad enligand cambian reacciones - catálisis
inert labile
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Estabilidad de Complejos de Ión Metálicos:Irving-Williams Series
Stability order for high-spin divalent metal ioncomplexes: Peak at Cu(II), Minimum at Mn(II)
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Proteína Ligantes – Residuos de AminoácidoMn prefiere ligar el oxígeno ligantes
N O S
His
Lys
Tyr
Glu(+Asp)
Ser
Cys
Met
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La superposición de estructura del metal se centra en in Fe-homoprotocatechuate 2,3-dioxygenase (PDB 2IG9) y Mn-HPCD
(PDB 3BZA) Atoms: gray C; blue N; red O; magenta Mn
J.P. Emerson et al. (2008) PNAS, 105, 7347 – 7352
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Humano Mn SOD TetramerBorgstahl et al. (1996) Biochemistry, 35, 4287-4297; Quint et al. (2006) Biochemistry, 45,
8209 – 8215
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Mn SODPDB 1VAR
http://en.wikipedia.org/wiki/Superoxide_dismutase
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The dismutation of superoxidemay be written as:
M(n+1)+-SOD + O2− → Mn+-
SOD + O2
Mn+-SOD + O2
− + 2H+ →M(n+1)+-SOD + H2O2.M = Cu (n=1); Mn (n=2) ; Fe(n=2) ; Ni (n=2).
The oxidation state of themetal cation oscillates betweenn and n+1.
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El sitio activo de Lactobacil lus plantarum Mn-catalase(Hexamer, PDB 1JKV and 1JKU; V.V. Barynin et al.(2001), Structure, 2001, 9, 725 – 738)
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2 H2O2 → 2 H2O + O2
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Azide (N3-) ligando en el sitio activo de Lactobacillusplantarum Mn-catalase
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Mn Ribonucleotide Reductase J.E. Martin, J.A. Imlay (2011), Mol Microbiol., 80, 319 – 334; J.A. Stubbe, J. A. Cotruvo
(2011), Curr Opin Chem Biol., 15, 284 – 290
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Ribonucleotide Reductase Chemistryhttp://en.wikipedia.org/wiki/Ribonucleotide_reductase
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Química Bioinorganic básica de Manganeso en todo a fotosíntesisLuz conducida en evolución de dioxygen
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A.W. Rutherford, A. Boussac (2004)
Science, 303, 1782-1784; S. Merchant, M.
Sawaya (2005) Plant cell 17, 648-663;D. A. Bryant, N.-U. Frigaard (2006) TRENDS
in Microbiology, 14, 488-496; T. M. Iverson
(2006) Current Opinion in Chemical
Biology , 10, 91 –100; D.G. Nocera (2012)
ACCOUNTS OF CHEMICAL RESEARCH, 45,
767 –
776.
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Introducción a Fotosíntesis(Britannica Enciclopedia en Línea)
http://www.britannica.com/EBchecked/topic/458172/photosynthesis
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O2 Evolving Complex (OEC), a Mn4CaO5
Cluster
BaMn8O16
Punto para recordar: Relase de oxígeno, larespuesta puede ser encontrada en las rocas
Mineral Hollandite:Ba0.8Pb0.2 Na0.1Mn
4+6.1Fe
3+1.3Mn
2+0.5Al0.2Si0.1O16
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(a) End-on view of the Hollandite lattice (tunneltype) consisting of Mn (red) and O (blue) atomsand showing the proposed location of Ba2+ cations
(gray) in the 2 × 2 tunnels (57, 58).There are two kinds of bridging O atoms, and oneof each kind is designated by vertical stripes (sp3-like) or horizontal stripes (sp2-like).(b ) Oblique view of the hollandite lattice shows the
difference in the mode of bridging of the sp3-like(apical) and sp2-like (planar) O atoms betweenthree Mn atoms.(c ) Expanded oblique view shows more clearly thedifferences between the sp3-like (vertical stripes)and sp2-like (horizontal stripes) bridging O atoms.
Sauer K , Yachandra VK (2002) PNAS, 99, 8631-8636
©2002 by National Academy of Sciences 30
El d ió F i é i (PS I) d b i d
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El centro de reacción Fotosintético (PS I) de bacterias moradasLuz conducida en síntesis de ATP
(C.D. Lancaster and H. Michel, Handbook of Metalloproteins 2001)
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Robert Huber, Premio Nobel
1988 (con Deisenhofer yMichel)
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El centro de reacción Fotosintético (PS I) de bacterias moradas(C.D. Lancaster and H. Michel, Handbook of Metalloproteins 2001)
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El t d ió F t i téti d b t i d
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El centro de reacción Fotosintético de bacterias moradas yTransferencia electrónica
(C.D. Lancaster and H. Michel, Handbook of Metalloproteins 2001)
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Módulos fundamentales del Aparato de Fotosíntesis
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Módulos fundamentales del Aparato de FotosíntesisLight-dependent reactions of photosynthesis at the thylakoid membrane
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookps.htmlhttp://www.phschool.com/science/biology_place/biocoach/photosynth/intro.html
http://en.wikipedia.org/wiki/Photosynthesis
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Respiración de Mitochondrial & Síntesis de Centro de ReacciónFotosintética de ATP – transferencia de electrón/protón
Conectada – fuerza de Protonmotive
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Módulos fundamentales del Aparato de FotosíntesisThe "Z scheme"
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookps.htmlhttp://www.phschool.com/science/biology_place/biocoach/photosynth/intro.html
http://en.wikipedia.org/wiki/Photosynthesis
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3D estructura de Fotosistema II de alga Synechococcus elongatus (3.8 Å resolution, Zouni et al. (2001), NATURE, 409 , 739)
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Cofactors de Fotosistema de Photosystem II (Synechococcus elongatus ) (water-oxidizing, OEC = oxygen-evolving complex, a 4 Mn cluster)
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Estructura de Clorofila. La estructura de clorofila b es mostrada con la Unión internacional deenumeración de Química Pura y Aplicada
Merchant S, Sawaya M. Plantcell 2005;17:648-663©2005 by American Society of Plant Biologists
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Chlorophyll (Mg) y Heme (Fe)
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Porphyrin ring y Phytol chain
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La oxidación de la agua, complejo que desarrolla el oxígeno,un 3Mn+1Mn cluster ???
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Estructura total de PSII dimer de T vulcanus en una
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Y Umena et al . Nature (2011) doi:10.1038/nature09913
Estructura total de PSII dimer de T. vulcanus en unaresolución de 1.9 Å
Umena1 et al. (2011), Nature, 473, 55-60
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O i ió d hl h ll
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Y Umena et al . Nature (2011) doi:10.1038/nature09913
Organización de chlorophylls
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Y Umena et al . Nature (2011) doi:10.1038/nature09913
Structure of the Mn4CaO5 cluster (OEC).
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The Mn4CaO5 Cluster (OEC)
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Y Umena et al . Nature (2011) doi:10.1038/nature09913
Hydrogen-bond network around YZ.
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The S-state (Kok) cycle showing how the absorption of four photons of light (h ν) byP680 drives the splitting of two water molecules and formation of O2 through aconsecutive series of five intermediates (S0, S1, S2, S3, and S4). The S-statesrepresent the various oxidation states of Mn in PSII-OEC. Electron donation fromthe PSII-OEC to P680•+ is mediated by tyrosine, YZ.
Published in: Daniel G. Nocera; Acc. Chem. Res. 2012, 45, 767-776.DOI: 10.1021/ar2003013
Copyright © 2012 American Chemical Society47
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Published in: Daniel G. Nocera; Acc. Chem. Res. 2012, 45, 767-776.DOI: 10.1021/ar2003013
Copyright © 2012 American Chemical Society
La Hoja artificial
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The solar photons are stored by photosynthesis to split water to oxygen and fourprotons and four electrons, which are utilized in the conversion of carbondioxide to carbohydrates.
Published in: Daniel G. Nocera; Acc. Chem. Res. 2012, 45, 767-776.DOI: 10.1021/ar2003013
Copyright © 2012 American Chemical Society49
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A simplified scheme of the light-driven reactions of photosynthesis. Solar photonscreate a wireless current that is harnessed by redox cofactors at the terminus of the
charge-separating network to translate the wireless current into a solar fuel byperforming the water splitting reaction at OEC. The initial reductant, plastoquinol(PQH2), is translated into NADPH in PSI, which transfers “hydrogen” to the Calvin
cycle where it is fixed with CO2 to produce carbohydrates.
Published in: Daniel G. Nocera; Acc. Chem. Res. 2012, 45, 767-776.DOI: 10.1021/ar2003013
Copyright © 2012 American Chemical Society
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(left) Schematic of cubane structure of PSII-OEC. (middle) Structure of the Co-OEC as determined from EXAFS (Pi not shown). Co-OEC is the head-to-taildimer of the cubane of PSII-OEC. (right) Co-OEC structure rotated by 45
tomore clearly shows edge sharing octahedra. The alkali metal ions, which are notshown, likely reside above the 3-fold triangle defined by the μ-bridging oxygens.
Published in: Daniel G. Nocera; Acc. Chem. Res. 2012, 45, 767-776.DOI: 10.1021/ar2003013
Copyright © 2012 American Chemical Society51
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Proposed pathway for water splitting by Co-OEC. A PCET equilibrium proceeds
the turnover-limiting O – O bond-forming step. Curved lines denote phosphate orterminal oxygen (from water or hydroxide). The oxyl radical in the far rightstructure is shown for emphasis. If the hole is completely localized on oxygen,then the Co oxidation state is Co(III) and not Co(IV).
Published in: Daniel G. Nocera; Acc. Chem. Res. 2012, 45, 767-776.DOI: 10.1021/ar2003013
Copyright © 2012 American Chemical Society
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Schematic of a Co-OEC functionalized npp +-silicon single-junction PEC cell.The buried junction performance characteristics are I sc = 26.7 mA/cm2 and V oc= 0.57 V.
Published in: Daniel G. Nocera; Acc. Chem. Res. 2012, 45, 767-776.DOI: 10.1021/ar2003013
Copyright © 2012 American Chemical Society
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R Vi i d M d d O í
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Resumen – Viviendo en una Mundo de OxígenoRespiración & Fotosíntesis
(energy conservation – ATP synthesis – proton-coupled-electron transfer)
• The use of the electron acceptor dioxygen and the photosyntheticproduction of dioxygen (water-oxidizing, oxygen-evolving complex) aretwo elementary processes of life which depend on a complex network ofmulti-site proteins and enzymes. Redox and light driven reactions areused for energy conservation (proton pumping; ATP synthesis).
• The 3Cu-2Fe, multi-subunit enzyme cytochrome c oxidase is the terminaloxidase of mitochondrial respiration, whereas the Mn4CaO5 cluster (witha tyrosine nearby) constitutes the oxygen evolving complex.
• The reduction of dioxygen to water proceeds without the release of ROS.COX receives the electrons via cytochrome c from where they aretransferred to the dinuclear mixed valence electron transfer center CuA.
• The dinuclear heme-CuB center constitutes the reduction site of dioxygen,which carries a covalently attached tyrosine at the active site.
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Resumen – Viviendo en una Mundo de OxígenoRespiración & Fotosíntesis
(energy conservation – ATP synthesis – coupled electron-proton transfer)
• COX represents a redox driven proton pump, with defined electron andproton transfer pathways (redox protons vs protons).
• The mechanism of dioxygen reduction is relatively well understood, itsmechanism has been characterized both by spectroscopic and structuraltechniques at high resolution. It appears that a tyrosine (radical), inaddition to Fe and Cu centers, is involved in catalysis.
• The dioxygen production (PS II) is a light-driven metalloradical enzymeprocess. The splitting of water and formation of dioxygen at the Mn4CaO5 cluster is still less understood despite a huge amount of spectroscopic andbiochemical studies. For Mn, cycling between oxidation states +2, +3, and+4, has been suggested (S-state model).
• New techniques have been employed to grow better crystals of theseextremely large membrane-bound molecules to achieve a resolution below2 Å, to understand their function on an atomic level.