Simple and Convenient Design of a Spectroelectrochemical Cell for In Situ XANES Measurements of Adsorbed Species in Transmission Mode

Xuan, Guang Shan; Jang, Suk-Man; Kwag, Gwanghoon; Kim, Sung-Hyun

doi:10.5012/bkcs.2005.26.4.671

Cited by 4 publications

References 12 publications

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Laboratory Evolution of P450 BM‐3 for Mediated Electron Transfer

Nazor

Schwaneberg

2006

ChemBioChem

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Preparative synthesis with P450 monooxygenases is hampered in cell-free systems by the requirement for cofactors such as NAD(P)H as reduction equivalents. A validated medium-throughput screening system was designed for improving P450 monooxygenases by mediated electron transfer with zinc/cobalt(III)sepulchrate (Zn/Co(III)sep) as an alternative and cost-effective cofactor system. The monooxygenase P450 BM-3 F87A was used as a model system for developing the screening system in a 96-well format. A coefficient of variation of less than 10% was achieved under optimized screening conditions. The mediator evolution screen was validated by comparing the activity of P450 BM-3 to P450 BM-3 F87A and by screening a saturation mutagenesis library at amino acid position R47. For mediated electron transfer, two double mutants P450 BM-3(F87A R47F) and P450 BM-3 (F87A R47Y) were identified with a two-threefold increased catalytic efficiency (up to 32 microM(-1) min(-1) for P450 BM-3(F87A R47F) and 34 microM(-1) min(-1) for P450 BM-3 (F87A R47Y)) compared to P450 BM-3 F87A. The kinetic constants of the double mutants are, in contrast to those of P450 BM-3 F87A, dependent on Co(III)sep concentration in the presence of NADPH. kcat increases from 145 min(-1) (0.25 mM Co(III)sep) to 197 min(-1) (0.5 mM Co(III)sep), and Km decreases simultaneously from 7.0 microM to 3.7 microM, for P450 BM-3 (F87A R47F). For P450 BM-3 (F87A R47Y), kcat increases from 138 min(-1) (0.25 mM Co(III)sep) up to 187 min(-1) (0.5 mM Co(III)sep), and Km decreases from 8.2 microM to 4.2 microM. Due to lower Km values, the catalytic efficiencies were improved six times for P450 BM-3 (F87A R47F) and three times for P450 BM-3 (F87A R47Y), when comparing catalytic efficiencies of the mediated electron-transfer system to the natural reduction equivalent NADPH.

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Laboratory Evolution of P450 BM‐3 for Mediated Electron Transfer

Nazor

Schwaneberg

2006

ChemBioChem

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In situ X‐ray Absorption Spectroscopy in Homogeneous Conditions Reveals Interactions Between CO₂ and a Doubly and Triply Reduced Iron(III) Porphyrin, then Leading to Catalysis

et al. 2023

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Iron porphyrins are attractive catalysts for the electrochemical reduction of carbon dioxide (CO2), owing to their high activity and selectivity while being tunable through ligand functionalization. Iron tetraphenyl porphyrin (FeTPP) is the simplest of them, and its catalytic behavior toward CO2 has been studied for decades. Although kinetic information is available, spectroscopic signatures are lacking to describe intermediate species along the catalytic cycle. In situ UV‐Visible and X‐ray absorption near edge spectroscopy (XANES) were used to monitor the local and electronic structure of FeTPP homogeneously dissolved in dimethyl formamide (DMF) under reductive potentials. The Fe(III) starting species was identified, together with its one, two and three electron‐reduced counterparts under both argon and CO2 atmospheres. Under argon, the second and third reductions lead to species with electronic density shared between the metal and the porphyrin backbone. In the presence of CO2 and with a low amount of protons, the doubly and triply reduced species interact with CO2 at the metallic site. In light of these results, an electronic structure for a key intermediate along the catalytic cycle of the CO2‐to‐CO reduction reaction is proposed.

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Practical Applications of Cage Metal Complexes

Voloshin

Belaya

Krämer

2017

Cage Metal Complexes

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Simple and Convenient Design of a Spectroelectrochemical Cell for In Situ XANES Measurements of Adsorbed Species in Transmission Mode

Cited by 4 publications

References 12 publications

Laboratory Evolution of P450 BM‐3 for Mediated Electron Transfer

Laboratory Evolution of P450 BM‐3 for Mediated Electron Transfer

In situ X‐ray Absorption Spectroscopy in Homogeneous Conditions Reveals Interactions Between CO₂ and a Doubly and Triply Reduced Iron(III) Porphyrin, then Leading to Catalysis

Practical Applications of Cage Metal Complexes

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Simple and Convenient Design of a Spectroelectrochemical Cell for In Situ XANES Measurements of Adsorbed Species in Transmission Mode

Cited by 4 publications

References 12 publications

Laboratory Evolution of P450 BM‐3 for Mediated Electron Transfer

Laboratory Evolution of P450 BM‐3 for Mediated Electron Transfer

In situ X‐ray Absorption Spectroscopy in Homogeneous Conditions Reveals Interactions Between CO2 and a Doubly and Triply Reduced Iron(III) Porphyrin, then Leading to Catalysis

Practical Applications of Cage Metal Complexes

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In situ X‐ray Absorption Spectroscopy in Homogeneous Conditions Reveals Interactions Between CO₂ and a Doubly and Triply Reduced Iron(III) Porphyrin, then Leading to Catalysis