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Membrane-Enclosed Enzymatic Catalysis (MEEC)
Published in Dale W. Blackburn, Catalysis of Organic Reactions, 2020
Eqs. 4-6 demonstrate the use of MEEC in oxidation, reduction and phosphorylation reactions. These reactions require the use of cofactors such as NADH, NAD and ATP. Equation 4 shows the synthesis of optically pure 2-hydroxy butyric acid 12 from keto acid 10 using D-lactate dehydrogenase (D-LDH; E.C.1.1.1.28).16 Formate dehydrogenase (FDH; E.C.1.2.1.2) is used to recycle the NADH cofactor via the oxidation of formic acid 11 to carbon dioxide. Eq. 5 represents a typical example for the use of horse liver alcohol dehydrogenase (HLADH; E.C.1.1.1.1) in the synthesis of optically pure lactones such as compound 14 from symmetrical diol 13.17 The enzyme L-lactate dehydrogenase (LDH; E.C.1.1.1.27) was used to recycle the NAD cofactor by reducing pyruvate to lactate.
Dark Fermentative Hydrogen Production:
Published in Farshad Darvishi Harzevili, Serge Hiligsmann, Microbial Fuels, 2017
Patrícia Madeira da Silva Moura, Joana Resende Ortigueira, Idania Valdez-Vazquez, Ganesh Dattatray Saratale, Rijuta Ganesh Saratale, Carla Alexandra Monteiro da Silva
Hydrogen production via pyruvate formate lyase (Pfl). The formate pathway for H2 production is characteristic of facultative anaerobic enteric bacteria. Hydrogen evolution results from the activity of Pfl and hydrogen formate lyase (Hfl), enzymes that are only expressed under anaerobic conditions. Pfl catalyzes the oxidation of pyruvate to produce acetyl-CoA and formate (Equation 7.6). Hfl, for its part, is a complex of two enzymes, formate dehydrogenase and hydrogenase (Kim and Gadd, 2008). Subsequently, formate dehydrogenase oxidizes formate to CO2, and under fermentative conditions, the electrons are transferred to the hydrogenase that catalyzes proton reduction and generates H2 (Equation 7.7). Hydrogen and carbon dioxide are produced at a 1:1 molar ratio, and this reaction is responsible for a maximum H2 yield of 2 mol/mol in glucose fermentation by Enterobacter aerogenes. Pyruvate+CoA→Acetyl-CoA+FormateFormate→CO2+2H++2e−→CO2+H2
Alcohol-Based Biofuel Cells
Published in Shelley Minteer, Alcoholic Fuels, 2016
Sabina Topcagic, Becky L. Treu, Shelley D. Minteer
The bioanode of the biofuel cell is the electrode at which the fuel is utilized by enzymes to produce electrons and protons, which are then utilized by enzymes of biocathodes to reduce O2 to H2O. Alcohol-based enzymatic systems that have been chosen most frequently for the bioanode involve NAD+-dependent alcohol dehydrogenase (ADH), which oxidizes alcohols to aldehydes. This enzyme can be employed with aldehyde dehydrogenase to further oxidize the aldehyde. Literature reports of alcohol biofuel cells are limited to only two alcohol-based enzymatic schemes. They are for methanol and ethanol and are shown in Figure 12.6. Methanol is oxidized to formaldehyde by alcohol dehydrogenase and then the formaldehyde is oxidized to formate by formaldehyde dehydrogenase. The formate is completely oxidized to carbon dioxide by formate dehydrogenase. The ethanol system involves oxidizing ethanol to acetaldehyde by alcohol dehydrogenase and then oxidizing the acetaldehyde to acetate by aldehyde dehydrogenase.
Tailoring of recombinant FDH: effect of histidine tag location on solubility and catalytic properties of Chaetomium thermophilum formate dehydrogenase (CtFDH)
Published in Preparative Biochemistry & Biotechnology, 2019
Hacer Esen, Saadet Alpdağtaş, Mehmet Mervan Çakar, Barış Binay
Formate dehydrogenase (FDH) is an oxidoreductase that catalyzes the conversion of formate into CO2 coupled with the reduction of NAD+ to NADH. These enzymes have attracted great attention due to their various biotechnological applications in different industries. It can be used as a recycler for expensive cofactors (NAD(P)H) in enzymatic synthesis of chiral intermediates such as 6-hydroxybispiron (the main metabolite of Buspirone, a drug used in the treatment of anxiety/depression) and (S)-N-boc-adamantane glycin (a remarkable component of Saxagliptin, type 2 diabetes mellitus drug)[8–10] in pharmaceutical industry. Moreover, it can be utilized for sequestration of greenhouse gases and also used as a formate sensor in different medical applications such as in diagnosis of methanol poisoning, nephrolithiasis, and pathogenic protozoans.[11–14]
Physico-chemical characterization of selected feedstocks as co-substrates for household biogas generation in Ghana
Published in International Journal of Sustainable Engineering, 2023
Blissbern Appiagyei Osei-Owusu, Martina Francisca Baidoo, Richard Arthur, Sampson Oduro-Kwarteng
At relatively low concentrations, micronutrients (trace metals) are critical cofactors in numerous enzymatic reactions involved in the biochemistry of methane formation (Arthur et al. 2022). Enzymes such as hydrogenase (containing Fe and or Ni) and formate dehydrogenase (containing Fe, Se, and Mo) release electrons from H2 and HCOOH during interspecies hydrogen/formate transfer (Banks et al. 2012). The Fe, Ni, Zn, Cr, Co, Cu, Cd, Mo, Mn and Se levels of HE, FLO, KR and CD in this study are summarised in Table 3. For all trace elements, a suitable concentration range between the maximum nutrient requirements and inhibition is established. In this study, Fe, Zn and Mn for all feedstocks lie outside the stimulatory concentration range, while Ni, Cr, Co, Cu, Cd and Se lie within (Table 4). Mo lies within the stimulatory concentration range for FLO and KR, but lies outside the range for CD and HE. The micronutrients in HE are in the order Fe>Zn>Mn>Cu>Mo>Cr>Ni>Co>Se>Cd, whereas those in FLO are in the order Fe>Zn>Mn>Cu>Ni>Cr>Mo>Co>Cd=Se. KR on the other hand, have micronutrients in the order Zn>Fe>Mn>Cu>Ni>Cr>Mo>Cd>Co=Se and CD, in the order Mn>Fe>Zn>Cr>Mo>Ni>Cu>Co>Cd=Se. Lin (1992) demonstrated that the relative toxicity of heavy metals to acetic acid degradation in mesophilic anaerobic digestion of sewage sludge was Cd>Cu>Cr=Zn>Pb>Ni. Evaluating heavy metal toxicity during anaerobic digestion of sewage sludge, Ahring and Westermann (1985) revealed severe inhibition at various concentrations for certain heavy metals, such as 70 to 400 mg/L for Cu, 200 to 600 mg/L for Zn, and 10 to 2000 mg/L for Ni.