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ScienceDirect Editorial overview: Bioinorganic chemistry: Bioinorganic catalysis for renewable energy Mi Hee Lim and Yi Lu Current Opinion in Chemical Biology 2015, 25:vii–viii For a complete overview see the Issue Available online 17th March 2015 http://dx.doi.org/10.1016/j.cbpa.2015.03.001 1367-5931/# 2015 Elsevier Ltd. All rights reserved.
Mi Hee Lim Department of Chemistry, Ulan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 689-798, Republic of Korea e-mail: [email protected] Mi Hee Lim is an Associate Professor in the Department of Chemistry at the Ulsan Institute of Science and Technology (UNIST), Ulsan, Korea. She obtained her MSc degree under Professor Wonwoo Nam at Ewha Womans University, Seoul, Korea, and a PhD degree under the supervision of Professor Stephen J. Lippard at MIT. She was a TRDRP postdoctoral fellow with Professor Jacqueline K. Barton at Caltech. Her current research focuses on elucidating the roles of metals, proteins, and reactive oxygen species in human neurodegenerative diseases.
Yi Lu1,2 1 Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, IL 61801, United States 2
Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, IL 61801, United States e-mail: [email protected]
Yi Lu is Jay and Ann Schenck Professor in the Department of Chemistry at the University of Illinois at Urbana-Champaign. He received his B.S. degree from Peking University, Ph.D. degree from UCLA under Professor Joan S. Valentine, and was a postdoctoral fellow in Professor Harry B. Gray group at Caltech. His research interests include (a) engineering functional metalloproteins as catalysts in renewable energy generation and pharmaceuticals; (b) understanding DNAzymes and their applications in environmental monitoring and medical diagnostics; and (c) directed assembly of nanomaterials with controlled morphologies and its applications in imaging and medicine.
www.sciencedirect.com
As the world population grows, with increased living standards, the consumption rate of fossil fuels and associated costs are dramatically rising. In order to face and conquer this global energy challenge, efficient methods to generate renewable energy are being sought after by a variety of research groups in academia and industry. Among them, bioinorganic chemists have been playing a prominent role because conversion of abundant resources, such as dioxygen (O2), carbon dioxide (CO2), water, and solar light, into fuels and other energy forms almost invariably requires metalloenzymes or bioinspired inorganic catalysts. In this issue of Current Opinion in Chemical Biology, we present eight review articles that summarize recent progresses in the field of renewable solar fuels and other energy-related catalysis in bioinorganic chemistry. A major focus in our search for sustainable energies is the transfer of solar energy into chemical energy and the sustainable production of solar fuels, such as hydrogen (H2) from water and carbon-based molecules from CO2 reduction. Despite much effort, metalloenzymes, such as the oxygen-evolving complex (OEC) in photosystem II (PSII), hydrogenase, carbon monoxide dehydrogenases (CODH), remain the most efficient catalysts for these reactions, with minimal driving force or overpotential and using earthabundant metal ions. Therefore, understanding how native enzymes perform these reactions efficiently is the first step toward developing artificial photosynthetic catalysts. While extensive attention has been paid to the role of the primary coordination sphere in conferring enzymatic activity, Brudvig and coworkers have reviewed experimental and computational findings of the importance of non-covalent secondary shell residues and associated hydrogen bonding network in controlling the water substrate exchange, Yz electron transfer, equilibrium between the S2 isomers, formation of the S3 state, and proton and O2 release pathways in the OEC. They have shown that these hydrogen-bond networks surrounding the OEC on the lumenal side of the PSII protein serve to stabilize charged intermediates and regulate the structure of the channels that allow transport of water, protons, and O2. Additionally, the efficient interconversion of protons (H+) and electrons (e ) is required for H2 production, activation, and transfer reactions. The article by Moore, Dahl, and Szymczak briefly illustrates the utility of the primary and secondary coordination environments surrounding the active site of the [Fe]-hydrogenase for the heterolysis of H2. The role of the 2-hydroxypyridine ligands, found in an iron cofactor of the [Fe]-hydrogenase, for handling of H+/e equivalents in reductive and oxidative catalysis is discussed, along with recent achievements in the homogeneous catalysts containing 2-hdyroxypryidine motifs. Current Opinion in Chemical Biology 2015, 25:vii–viii
viii Bioinorganic chemistry
Along with fine control of the residues around the primary coordination sphere within the same enzyme, the arrangement of different enzymes and their interactions with their partners are also very important in efficient energy conversion. Therefore, Bachmeier and Armstrong reviewed four different strategies in assembly of hydrogenase or CODH with their light-harvesting partners, with focus on insights gained from developing such artificial photosynthesis systems for tight electronic integration where both rates and efficiency are essential. Recent efforts for the development of artificial photosynthesis, including hybrids of natural and artificial components, are well summarized by Fukuzumi. The article by Fukuzumi also describes energy-efficient storage of H2 as a liquid or solid form, which is needed for stationary and portable H2-delivery infrastructure. In another review article that nicely complements the above articles, Utschig and coworkers have summarized recent advances in designing biohybrid systems composed of photosystem I (PSI) and different types of H2 catalysts, including protein catalysts, such as hydrogenase, noble metal catalysts, such as platinum-based nanomaterials, or earth abundant molecular catalysts, such as cobaloxime. Another innovative method includes encapsulation of a molecular catalyst within a flavodoxin protein enabling protein–protein interactions to control the reaction between the components in the biohybrid system. These systems have resulted in practical O2 tolerant, earth abundant photo-generation of H2 by combining Nature’s optimized PSI light capture and conversion capabilities with the creativity offered by synthetic chemistry. Given the work in both understanding native enzymes and synthesizing biomimetic complexes, it would be interesting to compare the two systems. Ye, Neese and coworkers have compared reaction mechanisms of the
Current Opinion in Chemical Biology 2015, 25:vii–viii
two-electron reduction of CO2 carried out by CODH and formate dehydrogenase (FDH) with those by chemical catalysts inspired by those enzymes. By summarizing the similarities between the two classes of catalysts, they offered important insights into future catalyst design, such as the important roles of the metal-(h1-CO2) interaction and the subsequent proton-coupled electron transfer for the [NiFe] CODH activity, and of the hydride transfer from metal-hybrids to the C-atom of CO2 to yield formate or formic acid for the FDH functionality. Moreover, the article by Ray, Heims, Schwalbe, and Nam reports the recent advance in reactivity of high-valent metal-oxo complexes related to energy conversion and conservation processes. Particularly, the mechanistic studies of biologically relevant metal-oxo cores, evidenced to be active intermediates during dioxygen reduction and water oxidation reactions, are focused in this review. In the last contribution, Lee and Karlin focus on how the structures and nature of the metal active sites in copper monooxygeneases can direct their reactivity toward substrates. In addition, recent efforts in the generation of synthetic analogs containing single copper active sites are described. Studies of copper–oxygen intermediates, proposed to be involved in reactivity of copper monooxygeneases, are also summarized. Association of electrons and/or protons, upon formation of such intermediates, is compared with that in aqueous O2-reduction, oxidase, and monooxygenase processes. We have enjoyed editing this edition of Current Opinion in Chemical Biology and we thank all of the authors who have contributed to this themed issue for their contributions and hope that the readers of the issue will be as inspired by the work as we have been.
www.sciencedirect.com
ScienceDirect Editorial overview: Bioinorganic chemistry: Bioinorganic catalysis for renewable energy Mi Hee Lim and Yi Lu Current Opinion in Chemical Biology 2015, 25:vii–viii For a complete overview see the Issue Available online 17th March 2015 http://dx.doi.org/10.1016/j.cbpa.2015.03.001 1367-5931/# 2015 Elsevier Ltd. All rights reserved.
Mi Hee Lim Department of Chemistry, Ulan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 689-798, Republic of Korea e-mail: [email protected] Mi Hee Lim is an Associate Professor in the Department of Chemistry at the Ulsan Institute of Science and Technology (UNIST), Ulsan, Korea. She obtained her MSc degree under Professor Wonwoo Nam at Ewha Womans University, Seoul, Korea, and a PhD degree under the supervision of Professor Stephen J. Lippard at MIT. She was a TRDRP postdoctoral fellow with Professor Jacqueline K. Barton at Caltech. Her current research focuses on elucidating the roles of metals, proteins, and reactive oxygen species in human neurodegenerative diseases.
Yi Lu1,2 1 Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, IL 61801, United States 2
Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Ave., Urbana, IL 61801, United States e-mail: [email protected]
Yi Lu is Jay and Ann Schenck Professor in the Department of Chemistry at the University of Illinois at Urbana-Champaign. He received his B.S. degree from Peking University, Ph.D. degree from UCLA under Professor Joan S. Valentine, and was a postdoctoral fellow in Professor Harry B. Gray group at Caltech. His research interests include (a) engineering functional metalloproteins as catalysts in renewable energy generation and pharmaceuticals; (b) understanding DNAzymes and their applications in environmental monitoring and medical diagnostics; and (c) directed assembly of nanomaterials with controlled morphologies and its applications in imaging and medicine.
www.sciencedirect.com
As the world population grows, with increased living standards, the consumption rate of fossil fuels and associated costs are dramatically rising. In order to face and conquer this global energy challenge, efficient methods to generate renewable energy are being sought after by a variety of research groups in academia and industry. Among them, bioinorganic chemists have been playing a prominent role because conversion of abundant resources, such as dioxygen (O2), carbon dioxide (CO2), water, and solar light, into fuels and other energy forms almost invariably requires metalloenzymes or bioinspired inorganic catalysts. In this issue of Current Opinion in Chemical Biology, we present eight review articles that summarize recent progresses in the field of renewable solar fuels and other energy-related catalysis in bioinorganic chemistry. A major focus in our search for sustainable energies is the transfer of solar energy into chemical energy and the sustainable production of solar fuels, such as hydrogen (H2) from water and carbon-based molecules from CO2 reduction. Despite much effort, metalloenzymes, such as the oxygen-evolving complex (OEC) in photosystem II (PSII), hydrogenase, carbon monoxide dehydrogenases (CODH), remain the most efficient catalysts for these reactions, with minimal driving force or overpotential and using earthabundant metal ions. Therefore, understanding how native enzymes perform these reactions efficiently is the first step toward developing artificial photosynthetic catalysts. While extensive attention has been paid to the role of the primary coordination sphere in conferring enzymatic activity, Brudvig and coworkers have reviewed experimental and computational findings of the importance of non-covalent secondary shell residues and associated hydrogen bonding network in controlling the water substrate exchange, Yz electron transfer, equilibrium between the S2 isomers, formation of the S3 state, and proton and O2 release pathways in the OEC. They have shown that these hydrogen-bond networks surrounding the OEC on the lumenal side of the PSII protein serve to stabilize charged intermediates and regulate the structure of the channels that allow transport of water, protons, and O2. Additionally, the efficient interconversion of protons (H+) and electrons (e ) is required for H2 production, activation, and transfer reactions. The article by Moore, Dahl, and Szymczak briefly illustrates the utility of the primary and secondary coordination environments surrounding the active site of the [Fe]-hydrogenase for the heterolysis of H2. The role of the 2-hydroxypyridine ligands, found in an iron cofactor of the [Fe]-hydrogenase, for handling of H+/e equivalents in reductive and oxidative catalysis is discussed, along with recent achievements in the homogeneous catalysts containing 2-hdyroxypryidine motifs. Current Opinion in Chemical Biology 2015, 25:vii–viii
viii Bioinorganic chemistry
Along with fine control of the residues around the primary coordination sphere within the same enzyme, the arrangement of different enzymes and their interactions with their partners are also very important in efficient energy conversion. Therefore, Bachmeier and Armstrong reviewed four different strategies in assembly of hydrogenase or CODH with their light-harvesting partners, with focus on insights gained from developing such artificial photosynthesis systems for tight electronic integration where both rates and efficiency are essential. Recent efforts for the development of artificial photosynthesis, including hybrids of natural and artificial components, are well summarized by Fukuzumi. The article by Fukuzumi also describes energy-efficient storage of H2 as a liquid or solid form, which is needed for stationary and portable H2-delivery infrastructure. In another review article that nicely complements the above articles, Utschig and coworkers have summarized recent advances in designing biohybrid systems composed of photosystem I (PSI) and different types of H2 catalysts, including protein catalysts, such as hydrogenase, noble metal catalysts, such as platinum-based nanomaterials, or earth abundant molecular catalysts, such as cobaloxime. Another innovative method includes encapsulation of a molecular catalyst within a flavodoxin protein enabling protein–protein interactions to control the reaction between the components in the biohybrid system. These systems have resulted in practical O2 tolerant, earth abundant photo-generation of H2 by combining Nature’s optimized PSI light capture and conversion capabilities with the creativity offered by synthetic chemistry. Given the work in both understanding native enzymes and synthesizing biomimetic complexes, it would be interesting to compare the two systems. Ye, Neese and coworkers have compared reaction mechanisms of the
Current Opinion in Chemical Biology 2015, 25:vii–viii
two-electron reduction of CO2 carried out by CODH and formate dehydrogenase (FDH) with those by chemical catalysts inspired by those enzymes. By summarizing the similarities between the two classes of catalysts, they offered important insights into future catalyst design, such as the important roles of the metal-(h1-CO2) interaction and the subsequent proton-coupled electron transfer for the [NiFe] CODH activity, and of the hydride transfer from metal-hybrids to the C-atom of CO2 to yield formate or formic acid for the FDH functionality. Moreover, the article by Ray, Heims, Schwalbe, and Nam reports the recent advance in reactivity of high-valent metal-oxo complexes related to energy conversion and conservation processes. Particularly, the mechanistic studies of biologically relevant metal-oxo cores, evidenced to be active intermediates during dioxygen reduction and water oxidation reactions, are focused in this review. In the last contribution, Lee and Karlin focus on how the structures and nature of the metal active sites in copper monooxygeneases can direct their reactivity toward substrates. In addition, recent efforts in the generation of synthetic analogs containing single copper active sites are described. Studies of copper–oxygen intermediates, proposed to be involved in reactivity of copper monooxygeneases, are also summarized. Association of electrons and/or protons, upon formation of such intermediates, is compared with that in aqueous O2-reduction, oxidase, and monooxygenase processes. We have enjoyed editing this edition of Current Opinion in Chemical Biology and we thank all of the authors who have contributed to this themed issue for their contributions and hope that the readers of the issue will be as inspired by the work as we have been.
www.sciencedirect.com
