Improvement in the Power Output of a Reverse Electrodialysis System by the Addition of Poly(sodium 4-styrenesulfonate)

Salinity gradient energy generated by the contact between seawater and river water is one of the promising renewable energies. In the reverse electrodialysis (RED), salinity gradient energy is directly translated into the electricity. The representative problem is a large electrical resistance of river water or dilute solutions. The dilute solutions are poor electrically conductive. This results in a huge energy loss when an electrical current passes through it. In this study, sodium chloride (NaCl) or poly(sodium 4-styrenesulfonate) (NaPSS) was added to the dilute solutions to increase the conductivities and enhance the power outputs of the RED cells. When NaCl was added, the power output reached 11.4 ± 0.6 µW. On the other hand, when NaPSS was added, the power output increased up to 19.6 ± 0.6 µW

Direct electron transfer-type bioelectrocatalysis by membrane-bound aldehyde dehydrogenase from Gluconobacter oxydans and cyanide effects on its bioelectrocatalytic properties

The bioelectrocatalytic properties of membrane-bound aldehyde dehydrogenase (AlDH) from Gluconobacter oxydans NBRC12528 were evaluated. AlDH exhibited direct electron transfer (DET)-type bioelectrocatalytic activity for acetaldehyde oxidation at several kinds of electrodes. The kinetic and thermodynamic parameters for bioelectrocatalytic acetaldehyde oxidation were estimated based on the partially random orientation model. Moreover, at the multi-walled carbon nanotube-modified electrode, the coordination of CN‾ to AlDH switched the direction of the DET-type bioelectrocatalysis to acetate reduction under acidic conditions. These phenomena were discussed from a thermodynamic viewpoint

Direct electron transfer-type bioelectrocatalysis of redox enzymes at nanostructured electrodes

Direct electron transfer (DET)-type bioelectrocatalysis, which couples the electrode reactions and catalytic functions of redox enzymes without any redox mediator, is one of the most intriguing subjects that has been studied over the past few decades in the field of bioelectrochemistry. In order to realize the DET-type bioelectrocatalysis and improve the performance, nanostructures of the electrode surface have to be carefully tuned for each enzyme. In addition, enzymes can also be tuned by the protein engineering approach for the DET-type reaction. This review summarizes the recent progresses in this field of the research while considering the importance of nanostructure of electrodes as well as redox enzymes. This review also describes the basic concepts and theoretical aspects of DET-type bioelectrocatalysis, the significance of nanostructures as scaffolds for DET-type reactions, protein engineering approaches for DET-type reactions, and concepts and facts of bidirectional DET-type reactions from a cross-disciplinary viewpoint

The Redox Potential Measurements for Heme Moieties in Variants of d-Fructose Dehydrogenase Based on Mediator-assisted Potentiometric Titration

The effect of mutation on the redox potentials (E degrees') of the heme moieties in the variants of D-fructose dehydrogenase (FDH) was investigated by mediated spectroelectrochemical titrations. The replacement of the axial ligand of heme from methionine to glutamine changes the E degrees' value more negatively than that of the corresponding heme moiety in the recombinant (native) FDH (rFDH). The determined E degrees' values of non-targeted heme moieties in the variants were also shifted in a negative direction from that in rFDH. Thus, enzyme modification changes E degrees' of the heme moieties in unmodified protein regions. (C) The Author(s) 2021. Published by ECSJ

Development Perspective of Bioelectrocatalysis-Based Biosensors

Bioelectrocatalysis provides the intrinsic catalytic functions of redox enzymes to nonspecific electrode reactions and is the most important and basic concept for electrochemical biosensors. This review starts by describing fundamental characteristics of bioelectrocatalytic reactions in mediated and direct electron transfer types from a theoretical viewpoint and summarizes amperometric biosensors based on multi-enzymatic cascades and for multianalyte detection. The review also introduces prospective aspects of two new concepts of biosensors: mass-transfer-controlled (pseudo)steady-state amperometry at microelectrodes with enhanced enzymatic activity without calibration curves and potentiometric coulometry at enzyme/mediator-immobilized biosensors for absolute determination

Role of a non-ionic surfactant in direct electron transfer-type bioelectrocatalysis by fructose dehydrogenase

A heterotrimeric membrane-bound fructose dehydrogenase (FDH) from Gluconobacter japonicus NBRC3260 contains FAD in subunit I and three heme C moieties in subunit II as the redox centers, and is one of the direct electron transfer (DET)-type redox enzymes. FDH-catalyzed current density of fructose oxidation at hydrophilic mercaptoethanol (MEtOH)-modified Au electrode is much larger than that at hydrophobic mercaptoethane (MEtn)-modified Au electrode. Addition of a non-ionic surfactant Triton® X-100 (1%) completely quenches the catalytic current at the MEtn-modified Au electrode, while only small competitive effect is observed at the MEtOH-modified Au electrode. Quartz crystal microbalance measurements support the adsorption of FDH and Triton® X-100 on both of the modified electrodes. We propose a model to explain the phenomenon as follows. The surfactant forms a monolayer on the hydrophobic MEtn-modified electrode with strong hydrophobic interaction, and FDH adsorbs on the surface of the surfactant monolayer. The monolayer inhibits the electron transfer from FDH to the electrode. On the other hand, the surfactant forms a bilayer on the hydrophilic MEtOH-modified electrode. The interaction between the surfactant bilayer and the hydrophilic electrode is relatively weak so that FDH replaces the surfactant and is embedded in the bilayer to communicate electrochemically with the hydrophilic electrode

Analysis of the oil biosynthesis transcripts of the Moringa oleifera Lam. mature seed embryos using RNA sequencing

Moringa oleifera seeds are capable of producing 40% edible oils that are gaining significance due to its nutritional advantages. Several studies have examined M. oleifera seed oil, nevertheless, these studies focused on the extraction of oil and methods of biodiesel production. There is a paucity of information on transcriptome level studies to determine the unigenes involved in oil biosynthesis metabolic pathways. The main objective of this study is to explore the transcriptome of the mature embryo of M. oleifera Lam. particularly the key genes related to oil biosynthesis. The transcriptome reflects the set of genes that are actively expressed at any given time produced in one or a population of cells in a given organism. Total RNA was extracted from 30 mature seed embryos obtained from 10 trees in Muñoz, Nueva Ecija, Philippines. RNA were pooled for cDNA library construction. Then, RNAsequencing was done followed by de novo sequence assembly to provide a costeffective and comprehensive means of transcriptome level information for M. oleifera. A total of 182,588 transcripts were generated in this study. Out of these transcripts, 3,556 unigenes are involved in oil biosynthesis. The most numerous group of unigenes are those involved in fatty acid biosynthesis with 1,009 unigenes, fatty acid catabolism with 982 unigenes and triacylglycerol catabolism with 608 unigenes. There are 33 unigenes encoding for transcription factors involved in regulating oil biosynthesis gene expression. This is the first transcriptome resource ever reported for M. oleifera mature seed embryo. These unigenes are unmatched in protein databases for M. oleifera. Hence, the transcriptome resource for the M. oleifera Lam. mature seed embryo generated in this study will be useful for the mapping of oil biosynthesis related genes and the understanding of metabolic pathways which could possibly be used to improve seed yield and oil content of M. oleifera

Triammonium hexa­hydroxidoocta­deca­oxidohexa­molybdogallate(III) hepta­hydrate

The title compound, (NH4)3[GaMo6(OH)6O18]·7H2O, contains two centrosymmetric GaMo6 B-type Anderson cluster units consisting of central GaO6 octa­hedra surrounded by a hexa­gonal assembly of MoO6 edge-sharing octa­hedra. Like other B-type Anderson clusters, where the central Mo atom is substituted with a di- or trivalent metal ion, the central six μ3-oxido bridges are protonated. The average Ga—O bond length is 1.97 (1) Å, whereas the average Mo—O distances are 2.29 (2), 1.94 (1) and 1.709 (5) Å, respectively, for Mo—(μ3-OH), Mo—(μ2-O) and Mo=O bonds. In the crystal structure, the Ga(μ3-OH)6Mo6O18 3− polyanionic clusters are surrounded by NH4 + cations and solvent water mol­ecules, forming an extended network of hydrogen bonds

An Exercise in Visualizing Colexification on a Semantic Map

This paper aims at investigating the polysemic patterns associated with the notion ‘soil/earth’ by using the semantic map model as a methodological tool. We focus on the applicability of the model to the lexicon, since most of past research has been devoted to the analysis of grammatical morphemes. The most concise result of our research is a diagrammatic visualization of the semantic spaces of twenty lexemes in nine different languages, mainly ancient languages belonging to the Indo-European and the Afro-Asiatic language families. The common semantic map for the various languages reveals that the semantic spaces covered by the investigated lexemes are often quite different from one another, although common patterns can also be detected. Our study highlights some shortcomings and methodological problems of previous analyses suggesting that a possible solution to these problems is the control of the data in the existing sources of the object languages. Finally, drawing upon the cognitive linguistics literature on the various types of semantic change, we show that some of the senses of the individual lexemes are the result of the function of such mechanisms as metaphor, metonymy, and generalization