Light-Driven CO2 Reduction by Co-Cytochrome b562

The current trend in atmospheric carbon dioxide concentrations is causing increasing concerns for its environmental impacts, and spurring the developments of sustainable methods to reduce CO2 to usable molecules. We report the light-driven CO2 reduction in water in mild conditions by artificial protein catalysts based on cytochrome b562 and incorporating cobalt protoporphyrin IX as cofactor. Incorporation into the protein scaffolds enhances the intrinsic reactivity of the cobalt porphyrin toward proton reduction and CO generation. Mutations around the binding site modulate the activity of the enzyme, pointing to the possibility of further improving catalytic activity through rational design or directed evolution.

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An NADH-Inspired Redox Mediator Strategy to Promote Second-Sphere Electron and Proton Transfer for Cooperative Electrochemical CO2 Reduction Catalyzed by Iron Porphyrin

10.26434/chemrxiv.12159207.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Peter T. Smith ◽

Sophia Weng ◽

Christopher Chang

Keyword(s):

Proton Transfer ◽

Co2 Reduction ◽

Iron Porphyrin ◽

Redox Mediators ◽

Reservoir Properties ◽

Proton Reduction ◽

Electrochemical Co2 Reduction ◽

Starting Point ◽

Rate Improvement ◽

Molecular Catalysts

We present a bioinspired strategy for enhancing electrochemical carbon dioxide reduction catalysis by cooperative use of base-metal molecular catalysts with intermolecular second-sphere redox mediators that facilitate both electron and proton transfer. Functional synthetic mimics of the biological redox cofactor NADH, which are electrochemically stable and are capable of mediating both electron and proton transfer, can enhance the activity of an iron porphyrin catalyst for electrochemical reduction of CO2 to CO, achieving a 13-fold rate improvement without altering the intrinsic high selectivity of this catalyst platform for CO2 versus proton reduction. Evaluation of a systematic series of NADH analogs and redox-inactive control additives with varying proton and electron reservoir properties reveals that both electron and proton transfer contribute to the observed catalytic enhancements. This work establishes that second-sphere dual control of electron and proton inventories is a viable design strategy for developing more effective electrocatalysts for CO2 reduction, providing a starting point for broader applications of this approach to other multi-electron, multi-proton transformations.

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Molecular Dynamics of Cobalt Protoporphyrin Antagonism of the Cancer Suppressor REV-ERBβ

Molecules ◽

10.3390/molecules26113251 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3251

Author(s):

Taufik Muhammad Fakih ◽

Fransiska Kurniawan ◽

Muhammad Yusuf ◽

Mudasir Mudasir ◽

Daryono Hadi Tjahjono

Keyword(s):

Binding Site ◽

Nuclear Receptor ◽

Target Genes ◽

Protoporphyrin Ix ◽

Binding Energies ◽

Metal Center ◽

Complex Nature ◽

Dynamic Simulations ◽

Subtle Change ◽

Cobalt Protoporphyrin

Nuclear receptor REV-ERBβ is an overexpressed oncoprotein that has been used as a target for cancer treatment. The metal-complex nature of its ligand, iron protoporphyrin IX (Heme), enables the REV-ERBβ to be used for multiple therapeutic modalities as a photonuclease, a photosensitizer, or a fluorescence imaging agent. The replacement of iron with cobalt as the metal center of protoporphyrin IX changes the ligand from an agonist to an antagonist of REV-ERBβ. The mechanism behind that phenomenon is still unclear, despite the availability of crystal structures of REV-ERBβ in complex with Heme and cobalt protoporphyrin IX (CoPP). This study used molecular dynamic simulations to compare the effects of REV-ERBβ binding to Heme and CoPP, respectively. The initial poses of Heme and CoPP in complex with agonist and antagonist forms of REV-ERBβ were predicted using molecular docking. The binding energies of each ligand were calculated using the MM/PBSA method. The computed binding affinity of Heme to REV-ERBβ was stronger than that of CoPP, in agreement with experimental results. CoPP altered the conformation of the ligand-binding site of REV-ERBβ, disrupting the binding site for nuclear receptor corepressor, which is required for REV-ERBβ to regulate the transcription of downstream target genes. Those results suggest that a subtle change in the metal center of porphyrin can change the behavior of porphyrin in cancer cell signaling. Therefore, modification of porphyrin-based agents for cancer therapy should be conducted carefully to avoid triggering unfavorable effects.

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Snowfall-albedo feedbacks could have led to deglaciation of snowball Earth starting from mid-latitudes

Communications Earth & Environment ◽

10.1038/s43247-021-00160-4 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Philipp de Vrese ◽

Tobias Stacke ◽

Jeremy Caves Rugenstein ◽

Jason Goodman ◽

Victor Brovkin

Keyword(s):

Carbon Dioxide ◽

Atmospheric Carbon Dioxide ◽

Climate Models ◽

Hydrological Cycle ◽

High Surface ◽

Dust Deposition ◽

Carbon Dioxide Concentrations ◽

Maximum Temperatures ◽

Carbon Dioxide Levels ◽

Earth’S Climate

AbstractSimple and complex climate models suggest a hard snowball – a completely ice-covered planet – is one of the steady-states of Earth’s climate. However, a seemingly insurmountable challenge to the hard-snowball hypothesis lies in the difficulty in explaining how the planet could have exited the glaciated state within a realistic range of atmospheric carbon dioxide concentrations. Here, we use simulations with the Earth system model MPI-ESM to demonstrate that terminal deglaciation could have been triggered by high dust deposition fluxes. In these simulations, deglaciation is not initiated in the tropics, where a strong hydrological cycle constantly regenerates fresh snow at the surface, which limits the dust accumulation and snow aging, resulting in a high surface albedo. Instead, comparatively low precipitation rates in the mid-latitudes in combination with high maximum temperatures facilitate lower albedos and snow dynamics that – for extreme dust fluxes – trigger deglaciation even at present-day carbon dioxide levels.

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An overview of flow cell architectures design and optimization for electrochemical CO2 reduction

Journal of Materials Chemistry A ◽

10.1039/d1ta06101a ◽

2021 ◽

Author(s):

Dui Ma ◽

Ting Jin ◽

Keyu Xie ◽

Haitao Huang

Keyword(s):

Carbon Dioxide ◽

Global Warming ◽

Electrochemical Reduction ◽

Atmospheric Carbon Dioxide ◽

Co2 Reduction ◽

Value Added ◽

Flow Cell ◽

Design And Optimization ◽

Electrochemical Co2 Reduction ◽

Carbon Dioxide Levels

Converting CO2 into value-added fuels or chemical feedstocks through electrochemical reduction is one of the several promising avenues to reduce atmospheric carbon dioxide levels and alleviate global warming. This approach...

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