| 1. |
- Santangelo, James S., et al.
(author)
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Global urban environmental change drives adaptation in white clover
- 2022
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375
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Journal article (peer-reviewed)abstract
- Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural dines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale.
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| 2. |
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| 3. |
- Adden, R, et al.
(author)
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New approaches to the analysis of enzymatically hydrolyzed methyl cellulose. Part 1. Investigation of the influence of structural parameters on the extent of degradation
- 2006
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In: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 7:5, s. 1399-1409
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Journal article (peer-reviewed)abstract
- Six methyl celluloses (MCs), one with a degree of substitution (DS) of 1.32 and five with DS between 1.83 and 1.88, were thoroughly investigated. Monomer composition and methyl distribution in the polymer chain were analyzed after total or partial random hydrolysis and appropriate derivatization with gas chromatography ( GC) and mass spectrometry (MS), respectively, and used as reference data. The same MCs were then hydrolyzed with an enzyme preparation of Trichoderma longibrachiatum and further investigated with size-exclusion chromatography with multiangle light scattering and refractive index detection (SEC-MALS/RI) and MS. Electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) in combination with various MS analyzers were compared with respect to quantification of the degradation products directly and after perdeuteriomethylation. The methyl group distribution in the oligomeric fractions and the average DS as a function of chain length were calculated from ESI mass spectra. With help of the reference analysis, patterns could be corrected for the unspecific contribution of end groups. By labeling and ESI tandem MS, our knowledge about the tolerance of the enzymes' sub-sites with respect to the number of methyl groups could be improved.
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| 4. |
- Bollella, Paolo, et al.
(author)
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Improved DET communication between cellobiose dehydrogenase and a gold electrode modified with a rigid self-assembled monolayer and green metal nanoparticles : The role of an ordered nanostructuration
- 2017
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In: Biosensors and Bioelectronics. - : Elsevier BV. - 0956-5663. ; 88, s. 196-203
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Journal article (peer-reviewed)abstract
- Efficient direct electron transfer (DET) between cellobiose dehydrogenase from Corynascus thermophilus (CtCDH) and a novel gold electrode platform, obtained by covalent linking of green AuNPs and AgNPs modified with a dithiol self-assembled monolayer, consisting of biphenyl-4,4′-dithiol (BPDT), was presented. The green AuNPs and AgNPs were synthesized using quercetin as reducing agent at room temperature. TEM experiments showed that the AuNPs and AgNPs were circular in shape with an average diameter of 5 and 8 nm, respectively. Cyclic voltammetry of CtCDH immobilized onto the AuNPs/BPDT/AuE and the AgNPs/BPDT/AuE electrode platforms were carried out and compared with naked AuE, BPDT/AuE, AuNPs/AuE, and AgNPs/AuE. A pair of well-defined redox waves in neutral pH solution due to efficient DET of CtCDH was present with both MNPs/BPDT/AuE platforms. No DET communication was found with platforms without MNPs linked to BPDT. The apparent heterogeneous electron transfer rate constants (kS) of CtCDH were calculated to be 21.5±0.8 s−1 and 10.3±0.7 s−1, for the AuNPs/BPDT/AuE and the AgNPs/BPDT/AuE platforms, respectively. The modified electrodes were successively used to develop an eco-friendly biosensor for lactose detection. The CtCDH/AuNPs/BPDT/AuE based biosensor showed the best analytical performances with an excellent stability, a detection limit of 3 µM, a linear range between 5 and 400 µM and a sensitivity of 27.5±2.5 µA cm−2 mM−1. Such performances were favorably compared with other lactose biosensors reported in literature. The biosensor was successively tested to quantify lactose content in real milk and cream samples. No significant interference present in the sample matrices was observed.
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| 5. |
- Christenson, Andreas, et al.
(author)
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Direct electron transfer between ligninolytic redox enzymes and electrodes
- 2004
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In: Electroanalysis. - : Wiley. - 1040-0397 .- 1521-4109. ; 16:13-14, s. 1074-1092
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Research review (peer-reviewed)abstract
- The electrochemistry of the ligninolytic redox enzymes, which include lignin peroxidase, manganese peroxidase and laccase and possibly also cellobiose dehydrogenase, is reviewed and discussed in conjunction with their basic biochemical characteristics. It is shown that long-range electron transfer between these enzymes and electrodes can be established and their ability to degrade lignin through a direct electron transfer mechanism is discussed.
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| 6. |
- Coman, Vasile, et al.
(author)
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A Direct Electron Transfer-Based Glucose/Oxygen Biofuel Cell Operating in Human Serum
- 2010
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In: Fuel Cells. - : Wiley. - 1615-6854 .- 1615-6846. ; 10:1, s. 9-16
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Journal article (peer-reviewed)abstract
- We report on the fabrication and characterisation of the very first direct electron transfer-based glucose/oxygen biofuel cell (BFC) operating in neutral glucose-containing buffer and human serum. Corynascus thermophilus cellobiose dehydrogenase and Myrothecium verrucaria bilirubin oxidase were used as anodic and cathodic bioelements, respectively. The following characteristics of the mediator-, separator- and membrane-less, a priori, non-toxic and simple miniature BFC, was obtained: an open-circuit voltage of 0.62 and 0.58 V, a maximum power density of ca. 3 and 4 mu W cm(-2) at 0.37 and 0.19 V of cell voltage, in phosphate buffer and human serum, respectively.
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| 7. |
- Craciunescu, I., et al.
(author)
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New electrode materials based on functionalized polypyrrole
- 2008
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In: JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS. - 1454-4164. ; 10:9, s. 2271-2276
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Conference paper (peer-reviewed)abstract
- New functional electrode materials, based on polypyrrole, were prepared by potentiostatic electro-copolymerization of pyrrole with two different pyrrole monomers, functionalized with carboxylic group: 3-(1-pyrrolyl)-propanoic acid and 4-oxo-4(1H-pyrrole-3-yl)butanoic acid. The properties of the polymeric electrode materials depend mainly on the synthesis method, monomers ratio, reaction time, and the composition of the supporting electrolyte. The obtained materials were characterized by Fourier transform infrared spectroscopy and cyclic voltammetry measurements. The poly-(pyrrole-co-beta-(1pyrrolyl) propanoic acid) copolymer, deposited on the surface of a glassy carbon electrode, was used as anchor for covalent immobilization of Toluidine Blue (TB), by coupling its aromatic amino group (position 3) with the carboxylic groups existing on the modified electrode. The covalent binding of TB onto the functionalized electrode surface results in a stable modified glassy carbon electrode, exhibiting a better electrochemical activity than that corresponding to poly-TB, obtained by TB electropolymerization on the same electrode surface.
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| 8. |
- Garjonyte, R, et al.
(author)
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Investigation of electrochemical properties of FMN and FAD adsorbed on titanium electrode
- 2003
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In: Bioelectrochemistry. - 1878-562X. ; 61:1-2, s. 39-49
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Journal article (peer-reviewed)abstract
- The electrochemical properties (such as the values of the formal potentials, the dependence of the formal potentials on solution pH, the reversibility of the electrochemical process) of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) adsorbed on a titanium electrode were dependent on the electrolyte. The formal potentials of adsorbed FMN and FAD in phosphate, HEPES and PIPES buffers at pH 7 were similar to those for dissolved flavins (−460 to −480 mV vs. SCE) and changed linearly with a slope of about 52 mV per pH unit in the pH region 3 to 8. In TRIS buffer, the formal potentials of adsorbed FMN and FAD were also pH-dependent, however, with invariance in the pH range 4.5 to 5.5. In non-buffered solutions (KCl, LiCl, NaCl, CsCl, CaCl2, Na2SO4 at different concentrations), the electrochemical behavior of adsorbed FMN and FAD differed from that of dissolved flavins and was dependent on the electrolyte (especially at pH 4.5 and pH 5). Under certain conditions (electrolyte, concentration, pH), a two-step oxidation of FMN could be observed
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| 9. |
- Ladiu, Carmen Ioana, et al.
(author)
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NADH electrocatalytic oxidation at glassy carbon paste electrodes modified with meldola blue adsorbed on acidic alpha-zirconium phosphate
- 2007
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In: Revue Roumaine de Chimie. - 0035-3930. ; 52:1-2, s. 67-74
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Journal article (peer-reviewed)abstract
- The electrochemical behavior and the electrocatalytic activity for the NADH oxidation at glassy carbon paste electrodes (GCPEs) modified with Meldola Blue (MB) adsorbed onto acidic cc-zirconium phosphate (ZP*) have been investigated. Cyclic voltammetry and rotating disc electrode measurements, performed in Tris buffer solution (pH 7) in absence and in presence of different NADH concentrations, showed that: (i) the formal standard potential (E degrees') of NIB was found pH dependent, according to the equation E = E degrees (c)-0.059pH + 0.029log(1 + 10(pH-pKa)), where the best fitting value for pK(a) Was estimated to be 4.3 +/- 0.4; (ii) the best electrocatalytic response was obtained for MB-ZP*-modified GCPEs having a ratio between the glassy carbon powder (Sigradur K) and MB-ZP* of 19:1; (iii) the presence of polyethyleneimine in the paste has a significant beneficial effect on the electrocatalytic activity of the investigated modified electrodes. As a general conclusion, it was stated that the particular features of the MB-ZP*-GCPEs are related to the ZP* crystallinity.
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| 10. |
- Melander, Claes, et al.
(author)
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New approaches to the analysis of enzymatically hydrolyzed methyl cellulose. Part 2. Comparison of various enzyme preparations
- 2006
-
In: Biomacromolecules. - : American Chemical Society (ACS). - 1526-4602 .- 1525-7797. ; 7:5, s. 1410-1421
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Journal article (peer-reviewed)abstract
- In this part of our studies, dealing with new approaches to the analysis of enzymatically hydrolyzed methyl cellulose, five different enzymes or enzyme preparations containing endoglucanases (from Bacillus agaradhaerens Cel 5A, Trichoderma reesei, Trichoderma Viride, and two obtained from Trichoderma longibrachiatum) were used to hydrolyze six different methyl celluloses (MCs). The main goal was to investigate whether enzymes could be used for determination of the heterogeneity of the substituent distribution along the cellulose chain. To obtain information about the heterogeneity, it was necessary to gather information on how the enzymes affect hydrolysis. Size exclusion chromatography with multi-angle light scattering and refractive index detection (SEC-MALS/RI) was used to estimate the molar mass distribution of the MCs before and after hydrolysis. A novel internal standard addition method in combination with electrospray ionization ion trap mass spectrometry (ESI-ITMS) was used to determine the amount of formed oligomers. Two MCs, one with a degree of substitution (DS) of 1.8 and one with DS 1.3, were hydrolyzed with all of the five enzymes. The yield of summarized di- and trisaccharides was approximately 2% of the hydrolysis products for the MC with DS 1.8, whereas the product mixture, obtained from a MC with a DS of 1.3, contained 7-16% di- and trisaccharides. By a novel sample preparation method in combination with ESI-IT tandem MS, outlined in part 1 of this work, it was shown that the enzymes produced oligomers with the reducing end bearing no or only one substituent. Comparison of the methyl pattern at the nonreducing ends of the dimers and trimers indicated that the -2 subsite of the active complex is less tolerant than subsites -3 and +1. All enzymes had similar general selectivity toward the methyl substituents but also showed some differences. From both SEC-MALS/RI and ESI-ITMS, differences with respect to substituent distribution of MCs could be recognized but not for each enzyme used. Basic considerations for enzymatic hydrolysis and analysis of methyl cellulose were listed as a consequence of the results from the work.
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| 11. |
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| 12. |
- Stoica, L., et al.
(author)
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Membrane-Less Biofuel Cell Based on Cellobiose Dehydrogenase (Anode)/Laccase (Cathode) Wired via Specific Os-Redox Polymers
- 2009
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In: Fuel Cells. - : Wiley. - 1615-6854 .- 1615-6846. ; 9:1, s. 53-62
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Journal article (peer-reviewed)abstract
- A membrane-free biofuel cell (BFC) is reported based on enzymes wired to graphite electrodes by means of Os-complex modified redox polymers. For the anode cellobiose dehydrogenase (CDH) is used as a biocatalyst whereas for the cathode a laccase was applied. This laccase is a high-potential laccase and hence able to reduce O-2 to H2O at a formal potential higher than +500 mV versus Ag/AgCl. In order to establish efficient electrochemical contact between the enzymes and graphite electrodes electrodeposition polymers containing Os-complex with specifically designed monomer compositions and formal potentials of the coordinatively bound Os-complex were synthesised and used to wire the enzymes to the electrodes. The newly designed CDH/Os-redox polymer anode was characterised at different pH values and optimised with respect to the nature of the polymer and the enzyme-to-polymer ratio. The resulting BFC was evaluated running on beta-lactose as a fuel and air/O-2 as an oxidising agent. The power output, the maximum current density and the electromotor force (E-emf) were found to be affected by the pH value, resulting in a maximum power output of 1.9 mu W cm(-2) reached at pH 4.3, a maximum current density of about 13 mu A cm(-2) at pH 3.5, and the highest E-emf approaching 600 mV at pH 4.0.
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| 13. |
- Stoica, Leonard, et al.
(author)
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Third-generation biosensor for lactose based on newly discovered cellobiose dehydrogenase
- 2006
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 78:2, s. 393-398
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Journal article (peer-reviewed)abstract
- The present paper describes the principle and characteristics of a biosensor for lactose based on a third-generation design involving cellobiose dehydrogenase. As resulted from a previous comparative study (submitted manuscript), the novelty of this lactose biosensor is based on highly efficient direct electron transfer between two newly discovered cellobiose dehydrogenases (CDH), from the white rot fungi Trametes villosa and Phanerochaete sordida, and a solid spectrographic graphite electrode. CDH was immobilized on the electrode surface (0.073 cm(2)) by simple physical adsorption, and the CDH-modified electrode was next inserted into a wall-jet amperometric cell connected on-line to a flow injection setup (0.5 mL(.)min(-1)). The P. sordida CDH-based lactose biosensor, proved to be the better one, has a detection limit for lactose of 1 mu M, a sensitivity of 1100 mu A(.)mM(-1.)cm(-2), a response time of 4 s (the time required to obtain the maximum peak current), and a linear range from 1 to 100 mu M lactose (correlation coefficient 0.998). The simplicity of construction and analytical characteristics make this CDH-based lactose biosensor an excellent alternative to previous lactose biosensors reported in the literature or commercially available. The CDH-lactose sensor was used to quantify the content of lactose in pasteurized milk, buttermilk, and low-lactose milk, using the standard addition method. No effects of the samples matrixes were observed. The operational stability of the sensor was tested for 11 h by continuous injection of 100 mu M lactose (290 injections). The final signal of the sensor was maintained at 98% of its initial signal, with a low standard deviation of 1.72 (RSD 2.41%).
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| 14. |
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| 15. |
- Tuoriniemi, Jani, 1982, et al.
(author)
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Determination of the Distance Between the Cytochrome and Dehydrogenase Domains of Immobilized Cellobiose Dehydrogenase by Using Surface Plasmon Resonance with a Center of Mass Based Model
- 2020
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 92:3, s. 2620-2627
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Journal article (peer-reviewed)abstract
- Changes in the tertiary conformation of adsorbed biomolecules can induce detectable shifts (Delta theta(r)) in the surface plasmon resonance (SPR) angle. Here it is shown how to calculate the corresponding shifts in the adsorbate's center of mass (Delta z(avg)) along the sensing surface normal from the measured Delta theta(r). The novel developed model was used for determining the mean distance between the cytochrome (CYT) and flavodehydrogenase (DH) domains of the enzyme cellobiose dehydrogenase (CDH) isolated from the fungi Neurospora crassa, Corynascus thermophilus, and Myriococcum thermophilum as a function of pH, [Ca2+], and substrate concentration. SPR confirmed the results from earlier electrochemical and SAXS studies stating that the closed conformation, where the two domains are in close vicinity, is stabilized by a lower pH and an increased [Ca2+]. Interestingly, an increasing substrate concentration in the absence of any electron acceptors stabilizes the open conformation as the electrostatic repulsion due to the reaped electrons pushes the DH and CYT domains apart. The accuracy of distance determination was limited mostly by the random fluctuations between replicate measurements, and it was possible to detect movements <1 nm of the domains with respect to each other. The results agreed with calculations using already established models treating conformational changes as contraction or expansion of the thickness of the adsorbate layer (t(protein)). Although the models yielded equivalent results, in this case, the Delta z(avg)-based method also works in situations, where the adsorbate's mass is not evenly distributed within the layer.
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