How does methylviologen cation radical supply two electrons to the formate dehydrogenase in the catalytic reduction process of CO2 to formate?

2020 ◽  
Vol 22 (33) ◽  
pp. 18595-18605 ◽  
Author(s):  
Akimitsu Miyaji ◽  
Yutaka Amao

The two-electron supply process using single-electron reduced methylviologen as a co-enzyme in the reduction process of CO2 to formate catalyzed by formate dehydrogenase from Candida boidinii was clarified by experimental and quantum chemical analyses.

2020 ◽  
Vol 22 (46) ◽  
pp. 26987-26994
Author(s):  
Akimitsu Miyaji ◽  
Yutaka Amao

Mechanism for formate dehydrogenase from Candida boidinii catalyzed CO2 reduction to formate with the cation radical of a 4,4′-bipyridinium salt with an ionic substituent as a co-enzyme was clarified by theoretical studies.


2021 ◽  
Vol 12 (12) ◽  
pp. 4526-4535
Author(s):  
Pascal Vermeeren ◽  
Michael T. Doppert ◽  
F. Matthias Bickelhaupt ◽  
Trevor A. Hamlin

Quantum chemical analyses reveal how model metallylene catalysts activate H2. This is the first step towards the rational design of metallylenes for the activation of small molecules and subsequent reactions.


2015 ◽  
Vol 71 (2) ◽  
pp. 313-323 ◽  
Author(s):  
Hyunjun Choe ◽  
Jung Min Ha ◽  
Jeong Chan Joo ◽  
Hyunook Kim ◽  
Hye-Jin Yoon ◽  
...  

CO2fixation is thought to be one of the key factors in mitigating global warming. Of the various methods for removing CO2, the NAD-dependent formate dehydrogenase fromCandida boidinii(CbFDH) has been widely used in various biological CO2-reduction systems; however, practical applications of CbFDH have often been impeded owing to its low CO2-reducing activity. It has recently been demonstrated that the NAD-dependent formate dehydrogenase fromThiobacillussp. KNK65MA (TsFDH) has a higher CO2-reducing activity compared with CbFDH. The crystal structure of TsFDH revealed that the biological unit in the asymmetric unit has two conformations,i.e.open (NAD+-unbound) and closed (NAD+-bound) forms. Three major differences are observed in the crystal structures of TsFDH and CbFDH. Firstly, hole 2 in TsFDH is blocked by helix α20, whereas it is not blocked in CbFDH. Secondly, the sizes of holes 1 and 2 are larger in TsFDH than in CbFDH. Thirdly, Lys287 in TsFDH, which is crucial for the capture of formate and its subsequent delivery to the active site, is an alanine in CbFDH. A computational simulation suggested that the higher CO2-reducing activity of TsFDH is owing to its lower free-energy barrier to CO2reduction than in CbFDH.


2021 ◽  
Vol 07 ◽  
Author(s):  
Wei Li

: Exploring low-cost, green and safe technologies to provide an alternative to the conventional selective catalytic reduction process is key to the control of NOx emitted from small-scale boilers and other industrial processes. To meet the demand, the chemical absorption-biological reduction integrated system has been developing recently. chemical absorption-biological reduction integrated system applies Fe(II)EDTA for NO absorption and iron-reducing and denitrifying bacteria for absorbent regeneration. Many studies have focused on the enhancements of mass transfer and biological reaction, among which the biological processes were the rate-limiting steps. This review summarizes the current researches on the biological processes in the CABR system, which focuses on the mechanism and enhancement of biochemical reactions, and provides the possible directions of future research.


2019 ◽  
Vol 74 (3-4) ◽  
pp. 101-104 ◽  
Author(s):  
Milja Pesic ◽  
Sébastien Jean-Paul Willot ◽  
Elena Fernández-Fueyo ◽  
Florian Tieves ◽  
Miguel Alcalde ◽  
...  

Abstract There is an increasing interest in the application of peroxygenases in biocatalysis, because of their ability to catalyse the oxyfunctionalisation reaction in a stereoselective fashion and with high catalytic efficiencies, while using hydrogen peroxide or organic peroxides as oxidant. However, enzymes belonging to this class exhibit a very low stability in the presence of peroxides. With the aim of bypassing this fast and irreversible inactivation, we study the use of a gradual supply of hydrogen peroxide to maintain its concentration at stoichiometric levels. In this contribution, we report a multienzymatic cascade for in situ generation of hydrogen peroxide. In the first step, in the presence of NAD+ cofactor, formate dehydrogenase from Candida boidinii (FDH) catalysed the oxidation of formate yielding CO2. Reduced NADH was reoxidised by the reduction of the flavin mononucleotide cofactor bound to an old yellow enzyme homologue from Bacillus subtilis (YqjM), which subsequently reacts with molecular oxygen yielding hydrogen peroxide. Finally, this system was coupled to the hydroxylation of ethylbenzene reaction catalysed by an evolved peroxygenase from Agrocybe aegerita (rAaeUPO). Additionally, we studied the influence of different reaction parameters on the performance of the cascade with the aim of improving the turnover of the hydroxylation reaction.


2014 ◽  
Vol 875-877 ◽  
pp. 213-217 ◽  
Author(s):  
Mohd Razali Sohot ◽  
Umi Sarah Jais ◽  
Muhd Rosli Sulaiman

Selective catalytic reduction (SCR) is a well-proven method to reduce NO emission. However, to choose the right catalyst that provides a surface for reaction between NO and ammonia at low temperatures is a challenging task for a catalysts developers. In an earlier study, we prepared V2O5-CeO2-SiO2 catalyst with increasing V2O5 content by sol-gel route and found that the catalytic activity improved with increasing the V2O5 loading up to 0.5%. The catalytic activity, however, dropped when V2O5 loading was about 1% and increased back when the loading of V2O5 was about 5%. In this study, we looked into the microstructural relationship to explain these findings. The microstructures of the catalysts before and after exposure to NO gas revealed that the catalysts with 0.2% and 0.5% V2O5 were more porous after the reduction process possibly due to improved breakdown of (NH4)HCO3 to NH3 by the possible interaction with the V2O5 and CeO2-containing catalysts which consequently resulted in a more efficient NO reduction to N2 and H2O at low temperature. The microstructure of the catalyst with 1% V2O5 content to 5%, improved back the efficiency although clogging by CeVO4 phase still possible due to its presence based on XRD. The well-ordered micropores before exposure to NO and the more efficient breakdown of (NH4)HCO3 could have contributed to increase back the catalytic activity at low temperature.


2021 ◽  
Author(s):  
Raed H. Althomali ◽  
Khalid A. Alamry ◽  
Mahmoud Hussein Abdo ◽  
Shams H. Abdel-Hafez

Abstract In this study, the catalytic reduction behavior of carboxylated alginic acid derivatives has been investigated against the harmful organic dyes including Methyl Orange (MO) and Congo Red (CR). Alginic acid was firstly oxidized through an easy addition of KMnO4 as an oxidizing agent. A carboxylated alginic acid (CAA) has been interacted with selected metal ions (Sn, Fe, Ni, and Zr) through coordination bonds at the value of pH = 4 to form the corresponding metal complexes namely: Sn-CAA, Fe-CAA, Ni-CAA and Zr-CAA. The consistency of the coordination was confirmed by several spectroscopic techniques including FT-IR, XRD, SEM, and EDX. The catalytic reduction of these metal ion-based products was carried out against MO and CR in the presence of NaBH4 as a reducing agent under UV irradiation. All catalysts based metal complexes showed enhanced catalytic reduction against CR compared to MO. Among all those mentioned metal complexes Sn-CAA showed the best catalytic reduction of these dyes. The time taken by the Sn-CAA for CR, and MO is 5 and 7min respectively. Ni-CAA was classified as the second efficient product against both dyes, where the reduction process took 20 and 9 min respectively. The other two catalysts took a long time for CR and MO reduction. Zr-CAA showed more than 80 % reduction of only CR dye within 20 min. Whereas, Fe-CAA did not show any significant sign of reduction against both the dyes after the same time. The order of higher catalytic reduction was illustrated as: Sn-CAA > Ni-CAA > Zr-CAA = Fe-CAA.


Author(s):  
Ryohei Sato ◽  
Yutaka Amao

In order to establish carbon capture, utilization, and storage (CCUS) technology, we focused on the system consisting of two different biocatalysts (formate dehydrogenase from Candida boidinii; CbFDH and carbonic anhydrase...


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