Publications

2000
2001
Ananyev, GM, Zaltsman L, Vasko C, Dismukes GC.  2001.  The inorganic biochemistry of photosynthetic oxygen evolution/water oxidation. Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1503:52-68.Website
Dismukes, GC, Klimov VV, Baranov SV, Kozlov YN, Dasgupta J, Tyryshkin A.  2001.  The origin of atmospheric oxygen on Earth: The innovation of oxygenic photosynthesis. Proceedings of the National Academy of Sciences of the United States of America. 98:2170-2175. AbstractWebsite
The evolution of O-2-producing cyanobacteria that use water as terminal reductant transformed Earth's atmosphere to one suitable for the evolution of aerobic metabolism and complex life. The innovation of water oxidation freed photosynthesis to invade new environments and visibly changed the face of the Earth. We offer a new hypothesis for how this process evolved, which identifies two critical roles for carbon dioxide in the Archean period. First, we present a thermodynamic analysis showing that bicarbonate (formed by dissolution of CO2) is a more efficient alternative substrate than water for O-2 production by oxygenic phototrophs. This analysis clarifies the origin of the long debated "bicarbonate effect" on photosynthetic O-2 production. We propose that bicarbonate was the thermodynamically preferred reductant before water in the evolution of oxygenic photosynthesis. Second, we have examined the speciation of manganese(II) and bicarbonate in water, and find that they form Mn-bicarbonate clusters as the major species under conditions that model the chemistry of the Archean sea. These clusters have been found to be highly efficient precursors for the assembly of the tetramanganese-oxide core of the water-oxidizing enzyme during biogenesis. We show that these clusters can be oxidized at electrochemical potentials that are accessible to anoxygenic phototrophs and thus the most likely building blocks for assembly of the first O-2 evolving photoreaction center, most likely originating from green nonsulfur bacteria before the evolution of cyanobacteria.
Yagi, M, Wolf KV, Baesjou PJ, Bernasek SL, Dismukes CG.  2001.  Selective Photoproduction of O2 from the Mn4O4 Cubane Core: A Structural and Functional Model for the Photosynthetic Water-Oxidizing Complex. Angewandte Chemie. 113:3009-3012.Website
Dismukes, GC.  2001.  Splitting Water. Science. 292:447-448.Website
2002
Sheats, JE, Micai K, Bleier S, Storey D, Sellito E, Carrell TG, Maneiro M, Bourles E, Dismukes GC, Rheingold AL et al..  2002.  Assembly of manganese-oxo clusters in solution as models for the photosynthetic oxygen-evolving complex. Macromolecular Symposia. 186:29-34.Website
Carrell, TG, Cohen S, Dismukes CG.  2002.  Oxidative catalysis by Mn4O46+ cubane complexes. Journal of Molecular Catalysis A: Chemical. 187:3-15.Website
2003
Maneiro, M, Ruettinger WF, Bourles E, McLendon GL, Dismukes CG.  2003.  Kinetics of proton-coupled electron-transfer reactions to the manganese-oxo “cubane” complexes containing the Mn4O and Mn4O core types. Proceedings of the National Academy of Sciences. 100:3707-3712. AbstractWebsite
The kinetics of proton-coupled electron-transfer (pcet) reactions are reported for Mn4O4(O2PPh2)6, 1, and [Mn4O4(O2PPh2)6]+, 1+, with phenothiazine (pzH). Both pcet reactions form 1H, by H transfer to 1 and by hydride transfer to 1+. Surprisingly, the rate constants differ by only 25% despite large differences in the formal charges and driving force. The driving force is proportional to the difference in the bond-dissociation energies (BDE >94 kcal/mol for homolytic, 1H → H + 1, vs. ≈127 kcal/mol for heterolytic, 1H → H− + 1+, dissociation of the O—H bond in 1H). The enthalpy and entropy of activation for the homolytic reaction (ΔH‡ = −1.2 kcal/mol and ΔS‡ = −32 cal/mol⋅K; 25–6.7°C) reveal a low activation barrier and an appreciable entropic penalty in the transition state. The rate-limiting step exhibits no H/D kinetic isotope effect (kH/kD = 0.96) for the first H atom-transfer step and a small kinetic isotope effect (1.4) for the second step (1H + pzH → 1H2 + pz•). These lines of evidence indicate that formation of a reactive precursor complex before atom transfer is rate-limiting (conformational gating), and that little or no N—H bond cleavage occurs in the transition state. H-atom transfer from pzH to alkyl, alkoxyl, and peroxyl radicals reveals that BDEs are not a good predictor of the rates of this reaction. Hydride transfer to 1+ provides a concrete example of two-electron pcet that is hypothesized for the O—H bond cleavage step during catalysis of photosynthetic water oxidation.
2004
Wu, J-Z, Sellitto E, Yap GPA, Sheats J, Dismukes CG.  2004.  Trapping an Elusive Intermediate in Manganese−Oxo Cubane Chemistry. Inorganic Chemistry. 43:5795-5797. AbstractWebsite
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2005
Ananyev, GM, Dismukes GC.  2005.  How fast can Photosystem II split water? Kinetic performance at high and low frequencies Photosynthesis Research. 84:355-365.Website
Dismukes, GC, Blankenship RE.  2005.  The origin and evolution of photosynthetic oxygen production. Photosystem Ii. 22:683-695.Website
Dismukes, GC, Ananyev GM, Watt R.  2005.  Photo-assembly of the catalytic manganese cluster. Photosystem Ii. 22:609-626.Website
Kruse, O, Rupprecht J, Mussgnug JR, Dismukes GC, Hankamer B.  2005.  Photosynthesis: a blueprint for solar energy capture and biohydrogen production technologies. Photochemical & Photobiological Sciences. 4:957-970. AbstractWebsite
Solar energy capture, conversion into chemical energy and biopolymers by photoautotrophic organisms, is the basis for almost all life on Earth. A broad range of organisms have developed complex molecular machinery for the efficient conversion of sunlight to chemical energy over the past 3 billion years, which to the present day has not been matched by any man-made technologies. Chlorophyll photochemistry within photosystem II (PSII) drives the water-splitting reaction efficiently at room temperature, in contrast with the thermal dissociation reaction that requires a temperature of ca. 1550 K. The successful elucidation of the high-resolution structure of PSII, and in particular the structure of its Mn4Ca cluster (K. N. Ferreira, T. M. Iverson, K. Maghlaoui, J. Barber and S. Iwata, Science, 2004, 303, 1831-1838, ref. 1) provides an invaluable blueprint for designing solar powered biotechnologies for the future. This knowledge, combined with new molecular genetic tools, fully sequenced genomes, and an ever increasing knowledge base of physiological processes of oxygenic phototrophs has inspired scientists from many countries to develop new biotechnological strategies to produce renewable CO2-neutral energy from sunlight. This review focuses particularly on the potential of use of cyanobacteria and microalgae for biohydrogen production. Specifically this article reviews the predicted size of the global energy market and the constraints of global warming upon it, before detailing the complex set of biochemical pathways that underlie the photosynthetic process and how they could be modified for improved biohydrogen production.
Wu, J-Z, De Angelis F, Carrell TG, Yap GPA, Sheats J, Car R, Dismukes CG.  2005.  Tuning the Photoinduced O2-Evolving Reactivity of Mn4O47+, Mn4O46+, and Mn4O3(OH)6+ Manganese−Oxo Cubane Complexes. Inorganic Chemistry. 45:189-195. AbstractWebsite
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Ananyev, GM, Nguyen T, Putnam-Evans C, Dismukes GC.  2005.  Mutagenesis of CP43-arginine-357 to serine reveals new evidence for (bi)carbonate functioning in the water oxidizing complex of Photosystem II. Photochemical & Photobiological Sciences. 4:991-998.Website
2006
Dasgupta, J, Tyryshkin AM, Kozlov YN, Klimov VV, Dismukes CG.  2006.  Carbonate Complexation of Mn2+ in the Aqueous Phase:  Redox Behavior and Ligand Binding Modes by Electrochemistry and EPR Spectroscopy. The Journal of Physical Chemistry B. 110:5099-5111. AbstractWebsite
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Carrieri, D, Kolling D, Ananyev GM, Dismukes C.  2006.  Prospecting for biohydrogen fuel. Industrial Biotechnology. 2:40-43.