Oxidoreductases: Significance for Humans and Microorganism

2020 ◽  
Author(s):  
Hussein Mahdi Kareem
Keyword(s):  
Large Class ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Diagnostic Tests ◽  
Organic Substrates ◽  
Biochemical Reactions ◽  
Biomass Processing ◽  
Oxidation Reduction ◽  
Special Case ◽  
Made In

Oxidoreductases consist of a large class of enzymes catalyzing the transfer of electrons from an electron donor (reductant) to an electron acceptor (oxidant) molecule. Since so many chemical and biochemical transformations comprise oxidation/reduction processes, it has long been an important goal in biotechnology to develop practical biocatalytic applications of oxidoreductases. During the past few years, significant breakthrough has been made in the development of oxidoreductase-based diagnostic tests and improved biosensors, and the design of innovative systems for the regeneration of essential coenzymes. Research on the construction of bioreactors for pollutants biodegradation and biomass processing, and the development of oxidoreductase-based approaches for synthesis of polymers and functionalized organic substrates have made great progress. Proper names of oxidoreductases are in a form of “donor:acceptor oxidoreductase”; while in most cases “donor dehydrogenase” is much more common. Common names also sometimes appeared as “acceptor reductase”, such as NAD+ reductase. “Donor oxidase” is a special case when O2 serves as the acceptor. In biochemical reactions, the redox reactions are sometimes more difficult to observe, such as this reaction from glycolysis: Pi + glyceraldehyde-3-phosphate + NAD+ → NADH + H+ + 1,3-bisphosphoglycerate, where NAD+ is the oxidant (electron acceptor), and glyceraldehyde-3-phosphate functions as reductant (electron donor).

scholarly journals Applications of Oxidoreductases

2020 ◽  
Author(s):  
Sandhya Rani Gogoi
Keyword(s):  
Electron Acceptor ◽  
Nicotinamide Adenine Dinucleotide ◽  
Diagnostic Tests ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Nicotinamide Adenine ◽  
Organic Substrates ◽  
Acceptor Molecule ◽  
Practical Applications ◽  
Oxidation Reduction ◽  
Potential Applications

Oxidoreductases comprise of a large group of enzymes catalyzing the transfer of electrons from an electron donor to an electron acceptor molecule, commonly taking nicotinamide adenine dinucleotide phosphate (NADP) or nicotinamide adenine dinucleotide (NAD) as cofactors. Research on the potential applications of oxidoreductases on the growth of oxidoreductase-based diagnostic tests and better biosensors, in the design of inventive systems for crucial coenzymes regeneration, and in the creation of oxidoreductase-based approaches for synthesis of polymers and oxyfunctionalized organic substrates have made great progress. This chapter focuses on biocatalytic applications of oxidoreductases, since many chemical and biochemical transformations involve oxidation/reduction processes, developing practical applications of oxidoreductases has long been a significant target in biotechnology. Oxidoreductases are appropriate catalysts owing to their biodegradability, specificity and efficiency and may be employed as improved biocatalysts to substitute the toxic/expensive chemicals, save on energy/resources consumption, generate novel functionalities, or reduce complicated impacts on environment.

Combining the biological nitrogen and sulfur cycles in anaerobic conditions

2001 ◽  
Vol 44 (8) ◽  
pp. 77-84 ◽  
Author(s):  
F. Fdz-Polanco ◽  
M. Fdz-Polanco ◽  
N. Fernández ◽  
M.A. Urueña ◽  
P.A. García ◽  
...  
Keyword(s):  
Electron Donor ◽  
Electron Acceptor ◽  
Sulfur Compounds ◽  
Ammonium Oxidation ◽  
Anaerobic Conditions ◽  
Reduced Sulfur Compounds ◽  
Gas Phases ◽  
Lack Of Information ◽  
Oxidation Reduction ◽  
Reduced Sulfur

The biochemical processes involved in the anaerobic degradation of carbon, nitrogen and sulfur compounds can be represented by an oxidation-reduction or electron donor-acceptor scheme. The theoretic values of Gibbs free energy (ΔG0) calculated from thermodynamic data indicate the feasibility of the reactions. The interactions C-S and C-N are well known but there is a lack of information about the interaction N-S. The anaerobic transformation of nitrates using reduced sulfur compounds can be explained considering that nitrate acts as electron acceptor while reduced sulfur compounds are the electron donors. A new N-S interaction in anaerobic conditions (ORP = -425 mV) has been experimentally observed when treating industrial wastewater rich in organic nitrogen and sulfate. The mass balances of the different nitrogenous and sulfur compounds in the liquid and gas phases clearly indicated an uncommon evolution. An important percentage of the nitrogen entering the reactor as TKN was removed from the liquid phase appearing as N2 in the gas phase. Simultaneously, only part of the sulfate initially present in the influent appeared as sulfide in the effluent or as hydrogen sulfide in the gas. These experimental observations may suggest a new anaerobic N-S biological interaction involving simultaneous anaerobic ammonium oxidation and sulfate reduction, ammonium being the electron donor and sulfate the electron acceptor.

scholarly journals Electricity Production by Geobacter sulfurreducens Attached to Electrodes

2003 ◽  
Vol 69 (3) ◽  
pp. 1548-1555 ◽  
Author(s):  
Daniel R. Bond ◽  
Derek R. Lovley
Keyword(s):  
Electron Transfer ◽  
Fuel Cells ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Microbial Fuel Cells ◽  
Electrical Current ◽  
Geobacter Sulfurreducens ◽  
Electricity Production ◽  
Organic Substrates ◽  
Current Production

ABSTRACT Previous studies have suggested that members of the Geobacteraceae can use electrodes as electron acceptors for anaerobic respiration. In order to better understand this electron transfer process for energy production, Geobacter sulfurreducens was inoculated into chambers in which a graphite electrode served as the sole electron acceptor and acetate or hydrogen was the electron donor. The electron-accepting electrodes were maintained at oxidizing potentials by connecting them to similar electrodes in oxygenated medium (fuel cells) or to potentiostats that poised electrodes at +0.2 V versus an Ag/AgCl reference electrode (poised potential). When a small inoculum of G. sulfurreducens was introduced into electrode-containing chambers, electrical current production was dependent upon oxidation of acetate to carbon dioxide and increased exponentially, indicating for the first time that electrode reduction supported the growth of this organism. When the medium was replaced with an anaerobic buffer lacking nutrients required for growth, acetate-dependent electrical current production was unaffected and cells attached to these electrodes continued to generate electrical current for weeks. This represents the first report of microbial electricity production solely by cells attached to an electrode. Electrode-attached cells completely oxidized acetate to levels below detection (<10 μM), and hydrogen was metabolized to a threshold of 3 Pa. The rates of electron transfer to electrodes (0.21 to 1.2 μmol of electrons/mg of protein/min) were similar to those observed for respiration with Fe(III) citrate as the electron acceptor (Eo′ =+0.37 V). The production of current in microbial fuel cell (65 mA/m2 of electrode surface) or poised-potential (163 to 1,143 mA/m2) mode was greater than what has been reported for other microbial systems, even those that employed higher cell densities and electron-shuttling compounds. Since acetate was completely oxidized, the efficiency of conversion of organic electron donor to electricity was significantly higher than in previously described microbial fuel cells. These results suggest that the effectiveness of microbial fuel cells can be increased with organisms such as G. sulfurreducens that can attach to electrodes and remain viable for long periods of time while completely oxidizing organic substrates with quantitative transfer of electrons to an electrode.

scholarly journals Betti numbers and pseudoeffective cones in 2-Fano varieties

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Giosuè Emanuele Muratore
Keyword(s):  
Large Class ◽  
Betti Numbers ◽  
Fano Varieties ◽  
Higher Dimensional ◽  
Special Case ◽  
Answering Questions

Abstract The 2-Fano varieties, defined by De Jong and Starr, satisfy some higher-dimensional analogous properties of Fano varieties. We consider (weak) k-Fano varieties and conjecture the polyhedrality of the cone of pseudoeffective k-cycles for those varieties, in analogy with the case k = 1. Then we calculate some Betti numbers of a large class of k-Fano varieties to prove some special case of the conjecture. In particular, the conjecture is true for all 2-Fano varieties of index at least n − 2, and we complete the classification of weak 2-Fano varieties answering Questions 39 and 41 in [2].

Preponderant role of pentafluorophenyl moieties for tuning the electronic properties of extended benzodifuran-azomethine derivatives

2021 ◽  
Author(s):  
Chady Moussallem ◽  
Magali Allain ◽  
Frédéric Gohier ◽  
Pierre Frere
Keyword(s):  
Electronic Properties ◽  
Electron Donor ◽  
Electron Acceptor

From a central 3,7-bis(perfluorophenyl)-BDF unit, the extension performed with electron acceptor perfluorophenyl groups and/or electron donor N,N-dimethylamino groups via an imine link leads to symmetrical AAA and DAD or dissymmetrical...

The chemistry of stabilized clusters

1982 ◽  
Vol 308 (1501) ◽  
pp. 27-34 ◽  
Keyword(s):  
Electron Donor ◽  
Organic Molecules ◽  
Metal Cluster ◽  
Organic Substrates ◽  
Insertion Reactions ◽  
Donor Ligand ◽  
Small Organic Molecules ◽  
Wide Range ◽  
Metal Metal ◽  
High Yields

Studies of the chemistry of metal cluster complexes and, in particular, their reactions with small organic molecules, have been confined to relatively few systems. Among the reasons for this are: (i) not many clusters are easily synthesized in high yields; (ii) their reactions often give a multitude of products that are difficult to separate and characterize; (iii) the conditions required to bring about reactions often lead to fragmentation of the cluster into lower nuclearity (often mononuclear) species. One cluster whose chemistry has been extensively studied is [Os 3 H 2 (CO) 10 ]. This can be synthesized in high yields from [Os 3 (CO) 12 ] + H 2 (Knox et al. 1975) and reacts readily under mild conditions with a wide range of electron-donor molecules by virtue of its coordinative unsaturation (Shapley et al. 1975; Deeming & Hasso 1976; Adams & Golembeski 1979). Formally, one may consider that a metal—metal double bond is present, which is reduced to a single bond on coordination of an additional two-electron donor ligand such as an organophosphine. The presence of metal—hydrogen bonds in this cluster and the cluster’s ability to coordinate organic substrates enable it to undergo a wide variety of insertion reactions, leading to products that may be regarded as intermediates in the reduction of organic molecules by clusters (Deeming & Hasso 1975; Keister & Shapley 1975).

scholarly journals p-HYDROQUINONE AND p-BENZOQUINONE AS HISTOCHEMICAL REAGENTS I. A NEW TETRAZOLIUM METHOD FOR AMINO GROUPS, AND THE MECHANISM OF FORMAZAN STAINING OF PARAFFIN AND FRESH FROZEN SECTIONS

1967 ◽  
Vol 15 (7) ◽  
pp. 404-408 ◽  
Author(s):  
G. G. CARMICHAEL ◽  
STEPHANIE T. K. MANDER
Keyword(s):  
Electron Acceptor ◽  
Thermal Shrinkage ◽  
Frozen Sections ◽  
Amino Groups ◽  
Paraffin Sections ◽  
Tetrazolium Bromide ◽  
Acid Ph ◽  
Reduction System ◽  
Oxidation Reduction ◽  
Fresh Frozen

The staining of amino groups by formazan when dehydrated paraffin sections are incubated in a mixture of hydroquinone and 3-(4,5-dimethyl thiazolyl-2)-2 ,5-diphenyl-2H-tetrazolium bromide at an acid pH is reported. The mechanism of this reaction and of the cytoplasmic deposition of formazan in fresh frozen sections incubated under similar conditions is investigated. It is shown that the oxidation of hydroquinone to semiquinone is responsible for the reaction, the tetrazole acting as electron acceptor. The tissue amino groups, exposed by dehydration and thermal shrinkage, and the nitrogen groupings of phosphobipid behave as "catalysts." The relevant properties of the hydroquinone-benzoquinone oxidation-reduction system are described, and the reactions between benzoquinone and tissue constituents are reviewed.

Microbial Perchlorate Reduction in Groundwater with Different Electron Donors

2013 ◽  
Vol 295-298 ◽  
pp. 1402-1407
Author(s):  
Rui Wang ◽  
Ming Chen ◽  
Jia Wen Zhang ◽  
Fei Liu ◽  
Hong Han Chen
Keyword(s):  
Removal Efficiency ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Reduction Rate ◽  
Electron Donors ◽  
Monod Equation ◽  
Hydrogen Addition ◽  
Perchlorate Reduction ◽  
Perchlorate Removal

Effects of different electron donors (acetate and hydrogen), acetate and perchlorate concentrations on microbial perchlorate reduction in groundwater were studied. The results showed that acetate and hydrogen addition as an electron donor can significantly improve perchlorate removal efficiency while a longer period was observed for hydrogen (15 d) than for acetate (8 d). The optical ratio of electron donor (acetate)-to-electron acceptor (perchlorate) was approximately 1.65 mg COD mg perchlorate-1. The highest specific reduction rate of perchlorate was achieved at the acetate-to-perchlorate ratio of 3.80 mg COD mg perchlorate-1. The perchlorate reduction rates corresponded well to the theoretical values calculated by the Monod equation and the parameters of Ks and Vm were determined to be 15.6 mg L-1 and 0.26 d-1, respectively.

Sign in / Sign up

Export Citation Format

Share Document