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The phosphate-addition induced improvement of the synthesis yield of fumarate from CO2 and pyruvate in an aqueous medium using a multi-biocatalytic system of ME from Sulfobus tokodaii and FUM from porcine heart in the presence of NADH was demonstrated.

Visible-light-driven 3-hydroxybutyrate production from low-concentration CO2 and waste acetone was developed for the first time by using the system of hybridized photocatalytic NADH regeneration and multi-biocatalysts.

The unsaturated dicarboxylate fumarate was produced from pyruvate and CO2 by applying malate dehydrogenase and fumarase as a catalyst for the visible-light driven regeneration of NADH for the first time.

One-pot β-hydroxybutyrate synthesis from CO2 and acetone in an aqueous solution with acetone carboxylase and β-hydroxybutyrate dehydrogenase extracted from Rhodobacter capsulatus SB1003 by culturing in an acetone–bicarbonate medium was developed.

Three kinds of heteroleptic Cu(I) complexes having a phenanthroline-based ligand acting as a chromophore and bearing benzoxazole, benzothiazole, and thiazole moieties were synthesized. Introduction...

The electrocatalytic reduction of formate to formaldehyde with formaldehyde dehydrogenase using methylviologen redox mediated was developed.

The biocatalytic synthesis of fumarate from CO2 and pyruvate vial-malate as an intermediate in an aqueous medium using a biocatalytic system consisting of malate dehydrogenase and fumarase in the presence of NADH is developed.

Bioelectrocatalytic methanol production from formaldehyde with alcohol dehydrogenase from Saccharomyces cerevisiae was developed toward establishing a method for synthesizing CO2 to methanol.

Visible-light driven 3-hydroxybutyrate from CO2 and acetone with the system of triethanolamine, zinc porphyrin, rhodium complex, NAD+ and a cell extract containing acetone carboxylase and 3-hydroxybutyrate dehydrogenase was accomplished.

It was clarified that bicarbonate and carbonate ions do not act as any inhibitor for the CbFDH-catalyzed CO2 reduction for the first time.

Effective H2 production based on formate decomposition with colloidal platinum nanoparticles dispersed by polyvinylpyrrolidone and a cationic polymer, poly(diallyldimethylammonium chloride), is accomplished.

Visible-light-driven molecular conversion using the NADH regeneration system of triethanol amine, water-soluble zinc porphyrin, colloidal Rh nanoparticles and NAD+ in the presence of various dehydrogenases was developed.

In order to establish carbon capture, utilization, and storage (CCUS) technology, we focused on a system consisting of two different biocatalysts (formate dehydrogenase from Candida boidinii; CbFDH and carbonic anhydrase from bovine erythrocytes; CA). CA catalyses the interconversion between CO2/water and dissociated bicarbonate ions/protons. CbFDH is a NAD+-dependent dehydrogenase that catalyzes CO2 reduction to formate by using the NAD+/NADH redox couple. The construction of a bienzymatic system consisting of CA and CbFDH (CA/CbFDH system) for a CCUS system was attempted. At 150 or 200 μM CA in the sample solution and a controlled pH of 6.3–6.5 by CO2 bubbling, due to the promotion of the conversion of CO2 to bicarbonate, the reaction rate for CbFDH-catalyzed CO2 reduction to formate decreased to about 50% as compared with that in the absence of CA. In the higher pH region (>9.5), despite the low CO2 concentration in this region, in contrast, it was found that the addition of CA promoted the reduction of CO2 catalyzed by CbFDH to formate to about 7 times higher than that under the conditions without CA. This shows that a CCUS system was constructed in which the conversion of bicarbonate to CO2 using CA and the reduction of CO2 to formate using CbFDH were coordinated.

A CdS photoanode with a smooth surface can stably oxidize [Fe(CN)6]4− by densely forming K2Cd[Fe(CN)6] on the CdS surface during photocorrosion.

The pH dependence of electron-donating ability of triethanolamine in visible-light driven H2 production system of water-soluble zinc porphyrin, methylviologen and colloidal platinum nanoparticle di...

The visible-light driven redox system of an electron donor, a photosensitizer, an electron mediator and formate dehydrogenase from Candida boidinii (CbFDH; EC.1.2.1.2) as a catalyst has received much attention for CO2 reduction to formate. In this system, elucidation of the electron transfer process between the electron mediator and CbFDH is important for improving efficiency of CO2 reduction to formate. 2,2′-Bipyridinium salt (2,2′-BP2+) is a remarkable electron mediator for CbFDH-catalyzed CO2 reduction. Especially, the direct interaction between cation radicals of 2,2′-BPs (2,2′-BP+•s) and CbFDH is a significant factor for the CO2 reduction. By using 1,1′-ethylene-2,2′-bipyridinium salt (DB2+), 1,1′-trimethylene-2,2′-bipyridinium salt (TB2+), 1,1′-tetramethylene-2,2′-bipyridinium salt (QB2+) and 1,1′-dimethyl-2,2′-bipyridinium salt (DM2+), 2,2′-BP+• with a small dihedral angle between the two pyridine rings (DB or TB) accelerates the CbFDH-catalyzed CO2 reduction. This work illuminated the direct interaction of the cation radicals of DB, TB, QB and DM in the substrate-binding site of CbFDH on the basis of a docking-simulated prediction. Moreover, the electron transfer process from the cation radicals of DB, TB, QB and DM to CO2 in the CbFDH was investigated based on the energy of the molecular orbital calculated by density functional theory (DFT). From these results, it can be predicted that efficient CO2 reduction to formate can be achieved by suppressing the three-dimensional structural change between the 2,2′-BP dication and the cation radical in the substrate-binding pocket of CbFDH as much as possible.

Photoredox catalytic systems are attracting widespread attention not only in the fields of water splitting into hydrogen and oxygen or CO2 reduction, but also in the field of organic synthesis for sustainable chemical such as biodegradable polymer and its raw material. As an example of the development of the photoredox catalyst system for organic synthesis, the visible-light driven selective pyruvate reduction to lactate (raw material for biodegradable polymer) with the system of triethanolamine (TEOA), zinc tetraphenylporphyrin tetrasulfonate (ZnTPPS), methylviologen (MV2+) and colloidal platinum nanoparticles dispersed polyvinylpyrrolidone (Pt-PVP) has been reported previously. In this work, improvement for visible-light driven selective lactate synthesis with this system was attempted by tuning an electron mediator or controlling the pH. The radical cation species is expected to be more effective in reducing pyruvate to lactate than hydride species in this system. From the result for pH controlling experimental, it was found that the protonated TEOA (TEOAH+) is strongly involved in the pyruvate reduction to lactate with this system under steady-state irradiation. Moreover, the racemic lactate was synthesized in this system.

A hybrid system with a CdS-modified CuInS2 as the photocathode, methylviologen (MV) as the electron mediator, and biocatalytic formate dehydrogenase from Candida boidinii was prepared for photoelectrochemical reduction of CO2 to formate. The photocathode exhibited a high photon-to-current conversion efficiency of ∼64% at 700 nm and 0.09 V vs. RHE.

Formate is attracting attention as a hydrogen carrier because of its low toxicity and easy handling in aqueous solution. In order to utilize formic acid as a hydrogen carrier, a catalyst for efficiently and selectively decomposing formic acid into H2 in a low pH region is required. In this work, enhancement of selective H2 production from formate with platinum nanoparticles dispersed by polyvinylpyrrolidone (PVP) and cationic poly-L-amino acid, poly(L-lysine) (PLL), poly(L-histidine)(PLH) and poly(L-arginine)(PLR) (Pt-PVP/PLX; X = L, H or R) in a low pH region was attempted. By using all Pt-PVP/PLX or Pt-PVP for formate decomposition catalysts, the amount of H2 produced was maximized using an aqueous formate solution with a pH of 3.5 (close to a pKa of 3.75 of formic acid). The H2 production catalytic activity of Pt-PVP/PLX (X = L or H) improved compared with that of Pt-PVP in the low pH range (pH = 1.8). By using Pt-PVP/PLL, especially, the amount of H2 produced was improved to about 1.8 times compared to that of Pt-PVP under a pH = 1.8 condition. There was no difference in the electronic states of the platinum nanoparticles in Pt-PVP and Pt-PVP/PLL according to the extended X-ray absorption fine structure and X-ray absorption near edge structure spectra measurements. The amount of H2 produced tended to increase as the PLL content ratio in Pt-PVP/PLL increased and the protonated alkylammonium moiety of PLL in Pt-PVP/PLL attracted the dilute formate ions in the solution to platinum nanoparticles, and the catalytic activity for H2 production was improved under the low pH range.

Visible-light-driven CO2 reduction to formate with a system consisting of water-soluble zinc tetraphenylporphyrin tetrasulfonate (ZnTPPS), formate dehydrogenase from Candida boidinii (CbFDH) and 1-amino-1′-carbamoyl-4,4′-bipyridinium salt (ACBP) as an electron mediator in the presence of triethanolamine (TEOA) as an electron donor was investigated. ACBP was prepared as the 4,4′-bipyridinium salt with amino and carbamoyl groups to promote an improvement in affinity with CbFDH. The properties of ACBP were characterized by photochemical and electrochemical approaches. The affinity between the single-electron reduced ACBP (ACBP+˙) and CbFDH was estimated using simple docking simulation. It was speculated from the docking simulation that ACBP+˙ binds near the substrate binding pocket of CbFDH like NAD+. In visible-light-driven ACBP reduction with the sensitization of ZnTPPS in the presence of TEOA, with the reduction yield of ACBP to ACBP+˙ estimated to be over 95%. In CO2 reduction to formate with a system consisting of TEOA, ZnTPPS, ACBP and CbFDH, the turnover numbers of ACBP and CbFDH were estimated to be 0.17 and 15.2 h−1, respectively.

We discovered the catalytic activity of Rh nanoparticles dispersed by polyvinylpyrrolidone (Rh–PVP) for NADH regeneration. The selective reduction of NAD+ to enzyme active NADH has successfully been achieved in the presence of an electron donor, ZnTPPS as a photosensitizer, and Rh–PVP. Only 1,4-NADH was produced as the reduction product of NAD+, which was validated by an enzymatic assay and HPLC.

Formate dehydrogenase from Candida boidinii (EC.1.2.1.2; CbFDH) is a commercially available enzyme and can be easily handled as a catalyst for the CO2 reduction to formate in the presence of NADH, single-electron reduced methylviologen (MV+˙) and so on. It was found that the formate oxidation to CO2 with CbFDH was suppressed using the oxidized MV as a co-enzyme and the single-electron reduced MV (MV+˙) was effective for the catalytic activity of CbFDH for the CO2 reduction to formate compared with that using the natural co-enzyme of NADH [Y. Amao, Chem. Lett., 2017, 46, 780-788]. The CO2 reduction to formate catalyzed by CbFDH requires two molecules of the MV+˙. In order to clarify the two-electron reduction process using MV+˙ in the CO2 reduction to formate catalyzed with CbFDH, we attempted enzyme reaction kinetics, electrochemical and quantum chemical analyses. Kinetic parameters obtained from the enzymatic kinetic analysis metric revealed an index of affinity of MV+˙ for CbFDH in the CO2 reduction to formate. From the results of the electrochemical analysis, it was predicted that only one molecule of MV+˙ was bound to CbFDH, and the MV bound to CbFDH was to be necessarily re-reduced by the electron source outside of CbFDH to supply the second electron in the CO2 reduction to formate. From the results of docking simulation and density functional theory (DFT) calculations, it was indicated that one molecule of MV bound to the position close to CO2 in the inner part of the substrate binding pocket of CbFDH contributed to the two-electron CO2 reduction to formate.

CO2 is a representative greenhouse gas (GHG), and the Paris Agreement adopted by consensus on 12 December 2015 mandates worldwide reduction of CO2 emissions by 80% until the end of 2050 relative to that of 2013. In order to achieve a significant reduction in CO2, it is necessary to establish not only CO2 capture and storage (CCS), but also a wide range of technologies such as CO2 conversion to alcohol fuels such as methanol, utilization as chemical raw materials, and so on (CO2 capture and utilization CCU). The establishment of utilization technology aimed at reducing CO2 will contribute to “7. Use of renewable feedstocks” and “9. Catalyst” from the 12 principles of green chemistry. CO2 utilization technology can be divided into two categories: multi-electron reduction with multiple protons and binding to organic molecules. In the former case, CO, formic acid, and methanol are produced, so no extension of the carbon number of the target product is observed. In the latter case, CO2 is bonded to the organic molecule as a carboxyl group, so that a C–C bond can be newly built. In other words, with the latter technology, it becomes possible to fix CO2 to organic molecules and create new functional materials. For example, natural photosynthesis skilfully utilizes sunlight as a renewable energy and enzyme catalysts to synthesize glucose from CO2 and water as a raw material. In other words, CCU technology based on mimicking natural photosynthesis contributes to the above principles of green chemistry. To establish this technology, a catalyst that promotes the binding of CO2 to organic molecules is an essential factor. In other words, it is necessary to develop a catalyst for activating C–H bonds in organic molecules and promoting C–C bond formation with CO2. In this review, molecular and enzyme-based catalysts for C–H bond activation and building C–C bonds with CO2 applicable to light-driven CCU using a photoredox system are introduced. Moreover, light-driven C–H bond activation and building C–C bonds with CO2 using various catalysts and photofunctional materials are also introduced. The reaction yield and selectivity of both systems for C–H bond activation and building C–C bonds with CO2 are also discussed. Finally, we discussed the problems of the light-driven C–H bond activation and building C–C bonds with CO2 and mentioned some areas for improvement in the future. We also discussed the outline of the life cycle assessment (LCA) of a typical system for light-driven C–H bond activation and building C–C bonds with CO2.

Malic enzyme (ME) from chicken liver (EC 1.1.1.40) is an enzyme that catalyzes the decarboxylation of malate into pyruvate and CO2 and the reverse reaction that introduces CO2 as a carboxy-group to pyruvate to form malate via oxaloacetate in the presence of natural co-enzyme NADP+/NADPH. Thus, ME is an attractive biocatalyst for building carbon–carbon bonds through the carboxylation of pyruvate with CO2. Since ME mainly catalyzes the decarboxylation of malate to produce pyruvate via oxaloacetate, it is necessary to devise ways to promote the carboxylation of pyruvate with CO2 to produce oxaloacetate based on the building of carbon–carbon bonds. Enhancing the carboxylation of pyruvate by the addition of metal ions with CO2 and using ME as a catalyst will lead to new insight into biocatalytic CO2 utilization research. The effect of adding divalent and trivalent metal ions to promote the ME-catalyzed building of carbon–carbon bonds through the carboxylation of pyruvate with CO2 was investigated. Specifically, it was found for the first time that the addition of trivalent aluminium and iron ions accelerates ME-catalyzed carboxylation of pyruvate with CO2. Moreover, it was found that a high concentration of aluminum ions (>100 μM) and a low concentration of iron ions (

Selective H2 production from formate with Pt nanoparticles dispersed by polyvinylpyrrolidone and cationic biopolymer, poly(L-lysine) (Pt–PVP/PLL), is attempted. Using Pt–PVP/PLL, the highly selective H2 production based on formate decomposition was accomplished compared with that of Pt–PVP. Moreover, using Pt–PVP/poly(L-glutamic acid), anionic biopolymer, the catalytic activity for selective H2 production based on formate decomposition was equivalent to that of Pt–PVP. This result suggests that the cationic site of PLL-captured formate ion and promoted the contact with the surface of Pt nanoparticles.

Formate dehydrogenase from Candida boidinii (CbFDH) reversibly catalyzes formate to carbon dioxide with the redox couple NAD+/NADH. There have been many studies on CbFDH-catalyzed oxidation of formate to carbon dioxide in the presence of NAD+. On the other hand, there are few studies on the detailed mechanism of the carbon dioxide reduction to formate catalyzed by CbFDH in the presence of NADH. In addition, it is not clear whether CbFDH can reduce carbon dioxide, bicarbonate or carbonate to formate. In this study, formate production with CbFDH in the presence of NADH was investigated in solutions with different ratios of carbon dioxide, bicarbonate and carbonate. The reaction rate of formate production with CbFDH increased in proportion to the concentration of carbon dioxide in the reaction solution. On the other hand, the formate production with CbFDH was suppressed in proportion to the concentration of bicarbonate or carbonate in the reaction solution. Thus, CbFDH was found to catalytically reduce only carbon dioxide to formate among the three types of carbonate species.

The utilization of the light-harvesting and electron-transferring function of chlorophylls (Chls) has received attention for visible-light driven hydrogen production. In this work, a series of Chl derivatives based on pyropheophorbide-a (Pyro-a) conjugated with a viologen moiety, including a Pyro-a methyl ester directly bonded with the viologen at the 3-position 1, its 31-methylene analog 2 and Pyro-a connected with the viologen in the 17-substituent 3, were synthesized from chemical modification of naturally occurring Chl-a and characterized in terms of their photochemical and photophysical properties. As the photoexcited singlet state of the Pyro-a moiety was strongly quenched by the viologen moiety in a molecule, the effective photoinduced intramolecular electron transfer from Pyro-a to the bonded viologen moiety occurred. Moreover, these molecules were applied as a photosensitizer in the system for visible-light driven hydrogen production with platinum nanoparticles via intramolecular reduction of the bonded viologen moiety. Efficient photoreduction of external methyl viologen and successive hydrogen production on platinum nanoparticles were achieved using the synthetic conjugate of Pyro-a with the viologen moiety as a photosensitizer. In particular, effective visible-light driven hydrogen production was accomplished using 3 and platinum nanoparticles via the reduction of external methyl viologen.

Selective hydrogen production from formic acid with platinum nano-cluster dispersed by various protective polymer based agents polyvinylpyrrolidone (Pt-PVP) or polyacrylic acid (Pt-PAA) is attempte...

Malate dehydrogenase (oxaloacetate-decarboxylating) commonly named malic enzyme (ME) from chicken liver (EC 1.1.1.40) catalyzes a reaction introducing CO2 as a carboxy-group to pyruvate to form mal...

1. Introduction Photocatalytic and photoelectrochemical (PEC) CO2 reductions using semiconductor materials under solar light have attracted significant attention. The development of CO2-reduction systems operating under visible-light irradiation is essential for the practical use of solar energy because visible light takes up almost half of the solar radiation spectrum. Most metal sulfides, such as CdS, have suitable conduction band levels for CO2 reduction and narrow bandgaps, enabling visible-light absorption. However, most metal sulfides are unstable in aqueous solution under photoirradiation due to the occurrence of self-oxidative deactivation (photocorrosion) by photogenerated holes (e.g., CdS + 2h+ → Cd2+ + S). CO2 reduction in an aqueous solution competes with H2 evolution because the CO2 reduction potential is more negative compared to the water reduction potential. Therefore, the catalysts that can selectively reduce CO2 have been utilized. Enzymes are biocatalysts that only act on specific substrates. For example, formate dehydrogenase (FDH) can reduce CO2 to formate with 100% selectivity by accepting electrons from coenzyme NADH. We have recently reported PEC reduction of CO2 to formate using a sacrificial reagent-free system consisting of a TiO2 photoanode and FDH.1 However, this system cannot utilize visible light owing to the wide bandgap of TiO2. In this study, we attempted to fabricate stable CdS photoanode and construct a hybrid system consisting of the CdS photoanode, NADH, and FDH for the reduction of CO2 to formate under visible-light irradiation. 2. Experimental The CdS photoanode was fabricated by the chemical bath deposition (CBD) method according to a previous report.2 The CdS electrode was calcined in N2 flow at 200, 300, and 400 °C for 30 min. The electrochemical cell used for photocurrent measurements comprised a prepared electrode, a counter electrode (Pt wire), an Ag/AgCl reference electrode, and a borate buffer solution (pH 8) containing K4[Fe(CN)6]•3H2O. The electrodes were irradiated using a 300 W Xe lamp fitted with an L-42 cut-off filter. CO2 reduction was carried out using two-electrode system (counter electrode: carbon paper) in phosphate buffer solution (pH 7) under CO2 bubbling. Rh complex [Cp*Rh(bpy)(H2O)]2+,3 NAD+, and FDH was added in the counter side. 3. Results and discussion The stabilities of the photocurrents of the CdS electrodes were evaluated at a fixed potential (–0.5 V vs. Ag/AgCl) under continuous visible light irradiation. As shown in Fig. 1a, for CdS electrodes with and without calcination at 200 and 300 °C, the photocurrent densities gradually decreased with the start of light irradiation. After the reaction, large cubic particles with a particle size of approximately 100–300 nm, reflecting the crystal structure of K2Cd[Fe(CN)6], were observed on the electrodes. XRD analysis also confirmed the formation of K2Cd[Fe(CN)6]. As previously reported, K2Cd[Fe(CN)6] forms spontaneously on the CdS surface during photoirradiation by reaction of dissolved Cd2+ cations via photocorrosion and [Fe(CN)6]4− anions in the solution.4 Therefore, this gradual decrease in photocurrent density was mainly due to the photocorrosion of CdS. In contrast, calcination at 400 °C positively influenced the CdS electrode, gradually increasing the photocurrent density. The number of electrons passing through the outer circuit for over 1 h (19.7 C, corresponding to 205 μmol) exceeded the number of moles of CdS (approximately 22 μmol) in the electrode. Although large K2Cd[Fe(CN)6] particles were observed on the CdS electrode after the reaction, the amount was significantly lower than that observed on the other electrodes. Instead, fine particles of K2Cd[Fe(CN)6] (particle size ~10 nm) were densely formed on the CdS surface. Therefore, fine K2Cd[Fe(CN)6] particles generated on the surface effectively scavenged photogenerated holes in CdS and enabled the oxidation of [Fe(CN)6]4− to [Fe(CN)6]3−.4 Reduction of NAD+ to NADH using [Cp*Rh(bpy)(H2O)]2+ as an electron mediator was examined in two-electrode system consisting of the CdS photoanode (calcined at 400 °C) and a carbon paper counter electrode with no applied bias (0 V). Relatively stable photocurrent (0.2 mA cm–2) was observed for 60 min. UV-vis spectroscopy and liquid chromatography analyses revealed that the amount of 1,4-NADH, which functions as a coenzyme, was increased with progression of reaction by reduction of NAD+ over the carbon electrode accepting electrons from CdS photoanode. The PEC reduction of CO2 to formate was attempted by introducing FDH in the system. As shown in Fig. 1b, the amount of produced formate was increased with the increasing irradiation time and reached 1285 nmol, which exceeded that of FDH (64 nmol). Ishibashi, M. Higashi, S. Ikeda, Y. Amao, ChemCatChem, 2019, 11, 6227. Ikeda, T. et al, ChemSusChem, 2011, 4, 262. Ruppert, et al, Tetrahedron Lett., 1987, 28, 6583. Shirakawa, M. Higashi, O. Tomita, R. Abe, Sustain. Energy Fuels, 2017, 1, 1065. Figure 1

Lactate has received a great deal of attention as a raw material for biodegradable plastics. Lactate is synthesized by fermentation and chemical procedures. Using chemical procedures, lactate is synthesized industrially by reacting acetaldehyde with hydrogen cyanide, a highly toxic substance, and hydrolysing the resultant lactonitrile. In this study, a selective pyruvate reduction to lactate using a visible light-driven redox system consisting of water-soluble zinc porphyrin as a photosensitizer, methylviologen as an electron mediator and platinum nanoparticles dispersed on poly(vinylpyrrolidone)(Pt-PVP) as a catalyst, is developed as a new lactate production method without toxic substances. By using this redox system, a reduction efficiency of pyruvate to lactate of up to 40% was achieved with visible light irradiation for 24 h. Furthermore, it was found that the addition of zinc acetate (up to about 13.5% of the initial concentration of pyruvate) to this photoredox system promoted lactate production due to the pyruvate reduction.

Formate dehydrogenase from Candida boidinii (CbFDH; EC.1.2.1.2) is a useful enzyme for CO2 reduction to formate in the photoredox system of a visible-light sensitizer and an electron mediator in the presence of an electron donor. The electron mediator, cation radicals of 4,4'-bipyridinium salts (4,4'-BPs) act as the co-enzyme for CbFDH in the CO2 reduction to formate. We found that the CbFDH-catalyzed CO2 reduction to formate could be controlled by the ionic substituents introduced into the cation radical of 4,4'-BPs [Y. Amao, Sustainable Energy Fuels, 2018, 2, 1928-1950]. By using 1,1'-diaminoethyl-4,4'-bipyridinium salt (DABP), 1-aminoethyl-1'-methyl-4,4'-bipyridinium salt (AMBP), 1,1'-carboxymethyl-4,4'-bipyridinium salt (DCBP), and 1-carboxymethyl-1'-methyl-4,4'-bipyridinium salt (CMBP), the introduction of an amino-group into 4,4'-BP accelerates the CbFDH-catalyzed CO2 reduction to formate, while the introduction of a carboxy-group into 4,4'-BP slows the CO2 reduction to formate. This work clarified the direct interaction of the cation radicals of DABP, DCBP, AMBP, CMBP, and MV in the substrate-binding site of CbFDH by the docking simulation. In addition, a mechanistic investigation for the CbFDH-catalyzed CO2 reduction to formate with cation radicals of DABP, DCBP, AMBP, CMBP, and MV was carried out based on the energy of molecular orbitals calculated by density functional theory (DFT).

Visible-light-driven CO

Formate dehydrogenase from Candida boidinii (EC.1.2.1.2; CbFDH) is a commercially available enzyme and can be easily handled as a catalyst for the CO