| 1. |
- Franco, Telma Teixeira, et al.
(författare)
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Single-step partitioning in aqueous two-phase systems
- 2000
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Ingår i: Aqueous Two-Phase Systems – Methods and Protocols. - New Jersey : Humana Press. - 9780896035416 - 9781617370670 - 9781592590285 ; , s. 47-54
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Bokkapitel (refereegranskat)abstract
- Partitioning in aqueous two-phase system (ATPS) provides a rapid and gentle means of separation of soluble as well as particulate biomaterials, e.g. proteins, nucleic acids, cells, viruses, organelles, and membranes. Partitioning between the two phases is a complex phenomenon, guided mainly by the interaction of the partitioned substance and the phase components, e.g., through hydrogen bonds, van der Waals-, hydrophobic-, and electrostatic- interactions, steric-, and conformational effects, etc.
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| 2. |
- Hatti-Kaul, Rajni, et al.
(författare)
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Aqueous two-phase systems : A general overview
- 2000
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Ingår i: Aqueous Two-Phase Systems : Methods and Protocols - Methods and Protocols. - New Jersey : Humana Press. - 9780896035416 - 9781617370670 - 9781592590285 ; , s. 1-10
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Bokkapitel (refereegranskat)abstract
- Phase separation in solutions containing polymer mixtures is a very common phenomenon; in fact, miscibility of the polymer mixtures is an exception. Most hydrophilic polymer pairs are incompatible in aqueous solutions yielding two coexisting phases in equilibrium with each other, with each of the phases containing predominantly water and one of the polymer types. It is worth noting that the association of unlike polymer species into a polymer-rich phase coexisting with a polymer-poor phase, referred to as complex coacervation can also occur. However, it is the former type of phase systems that form the subject of this book.
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| 3. |
- Hatti-Kaul, Rajni, et al.
(författare)
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Extractive bioconversion in aqueous two-phase systems
- 2000
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Ingår i: Aqueous Two-Phase Systems : Methods and Protocols - Methods and Protocols. - New Jersey : Humana Press. - 9780896035416 - 9781617370670 - 9781592590285 ; , s. 411-417
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Bokkapitel (refereegranskat)abstract
- Biotechnological processes are characterized, in general, by low productivity and dilute product streams.
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| 4. |
- Kamihira, Masamichi, et al.
(författare)
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Integration of extraction with affinity precipitation
- 2000
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Ingår i: Aqueous Two-Phase Systems : Methods and Protocols - Methods and Protocols. - New Jersey : Humana Press. - 9780896035416 - 9781617370670 - 9781592590285 ; , s. 371-379
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Bokkapitel (refereegranskat)abstract
- Conventional aqueous two-phase extraction by spontaneous partitioning has often problems with low specificity. The introduction of an affinity ligand into one of the phases has been attempted to enhance the specificity of protein partitioning (1-7; Chapters 29-31). However, this procedure still has some limitations in the effective removal of impurities as well as recovery and reuse of the ligand. During the past decade, another potentially scalable technique, affinity precipitation, has been studied for the isolation of proteins (8-10). The affinity ligand coupled to a reversibly soluble-insoluble polymer is used to specifically bind the protein in a complex mixture. The precipitation step which can be accomplished by a change in any environmental parameter such as pH, temperature, salinity, and so forth, facilitates the separation of the bound ligand and affinity complex from the unbound components. Although cells and cell debris should be removed before use, recovery and reuse of the ligand are relatively easy.
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| 5. |
- Kawde, Anurag, et al.
(författare)
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Photoelectrochemical oxidation in ambient conditions using earth-abundant hematite anode : A green route for the synthesis of biobased polymer building blocks
- 2021
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Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- This study demonstrates the use of a photoelectrochemical device comprising earth-abundant hematite photoanode for the oxidation of 5-hydroxymethylfurfural (5-HMF), a versatile bio-based platform chemical, under ambient conditions in the presence of an electron mediator. The results obtained in this study showed that the hematite photoanode, upon doping with fluorine, can oxidize water even at lower pH (4.5 and 9.0). For 5-HMF oxidation, three different pH conditions were investigated, and complete oxidation to 2,5-furandicarboxylic acid (FDCA) via 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) was achieved at pH above 12. At lower pH, the oxidation followed another route via 2,5-diformylfuran (DFF), yielding 5-formyl-2-furancarboxylic acid (FFCA) as the main product. Using the oxidized intermediates as substrates showed DFF to be most efficiently oxidized to FDCA. We also show that, at pH 4.5, the addition of the laccase enzyme promoted the oxidation of 5-HMF to FFCA.
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| 6. |
- Belgrano, Fabricio dos Santos, et al.
(författare)
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Cell immobilization on 3D-printed matrices : A model study on propionic acid fermentation
- 2018
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524. ; 249, s. 777-782
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Tidskriftsartikel (refereegranskat)abstract
- This study uses three-dimensional (3D) printing technology as a tool for designing carriers for immobilization of microbial cells for bioprocesses. Production of propionic acid from glucose by immobilized Propionibacterium sp. cells was studied as a model system. For cell adsorption, the 3D-printed nylon beads were added to the culture medium during 3 rounds of cell cultivation. Cell adsorption and fermentation kinetics were similar irrespective of the bead size and lattice structure. The cells bound to 15 mm beads exhibited reduced fermentation time as compared to free cell fermentations; maximum productivity and propionic acid titer of 0.46 g/L h and 25.8 g/L, respectively, were obtained. Treatment of the beads with polyethyleneimine improved cell-matrix binding, but lowered the productivity perhaps due to inhibitory effect of the polycation. Scanning electron micrographs revealed the cells to be located in crevices of the beads, but were more uniformly distributed on PEI-coated carrier indicating charge-charge interaction.
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| 7. |
- Abouhmad, Adel, et al.
(författare)
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Exploring the enzymatic and antibacterial activities of novel mycobacteriophage lysin b enzymes
- 2020
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 21:9
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Tidskriftsartikel (refereegranskat)abstract
- Mycobacteriophages possess different sets of lytic enzymes for disruption of the complex cell envelope of the mycobacteria host cells and release of the viral progeny. Lysin B (LysB) enzymes are mycolylarabinogalactan esterases that cleave the ester bond between the arabinogalactan and mycolic acids in the mycolylarabinogalactan-peptidoglycan (mAGP) complex in the cell envelope of mycobacteria. In the present study, four LysB enzymes were produced recombinantly and characterized with respect to their enzymatic and antibacterial activities. Examination of the kinetic parameters for the hydrolysis of para-nitrophenyl ester substrates, shows LysB-His6 enzymes to be active against a range of substrates (C4-C16), with a catalytic preference towards p-nitrophenyl laurate (C12). With p-nitrophenyl butyrate as substrate, LysB-His6 enzymes showed highest activity at 37◦C. LysB-His6 enzymes also hydrolyzed different Tween substrates with highest activity against Tween 20 and 80. Metal ions like Ca2+ and Mn2+ enhanced the enzymatic activity of LysB-His6 enzymes, while transition metal ions like Zn2+ and Cu2+ inhibited the enzymatic activity. The mycolylarabinogalactan esterase activity of LysB-His6 enzymes against mAGP complex was confirmed by LC-MS. LysB-His6 enzymes showed marginal antibacterial activity when tested alone against Mycobacterium smegmatis, however a synergetic activity was noticed when combined with outer membrane permealizers. These results confirm that LysB enzymes are lipolytic enzymes with potential application as antimycobacterials.
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| 8. |
- Alvarez, Maria Teresa, et al.
(författare)
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Lab-scale production of biogenic sulphide for metal precipitation in remote areas
- 2012
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Ingår i: International Journal of Environment and Waste Management. - 1478-9876. ; 9:3-4, s. 313-329
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Tidskriftsartikel (refereegranskat)abstract
- Batch cultures with wheat straw, biomass of Paja Brava (Festuca orthophylla), filter paper, newspaper and beech leaves (Fagus sylvatica) were established to produce sulphide. Sulphide production, sulphate reduction, concentration of Volatile Fatty Acids (VFAs), enzyme activities and Fluorescence in situ hybridisation were determined. Approximately 5 mM of sulphide was produced during anaerobic digestion of wheat straw, while the production with newspaper as carbon source was the lowest (ca.1 mM). The sulphide production (2-5 mM) in the semi-continuous culture of the consortium A10, using wheat straw supported Cu(II), Pb (II) and Zn (II) removal up to 90%.
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| 9. |
- Bakhtiar, Shahrzad, et al.
(författare)
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Stability characteristics of a calcium-independent alkaline protease from Nesterenkonia sp.
- 2003
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Ingår i: Enzyme and Microbial Technology. - 0141-0229. ; 32:5, s. 525-531
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Tidskriftsartikel (refereegranskat)abstract
- Thermodynamic stability of an alkaline protease from a new alkaliphilic Nesterenkonia sp. AL-20, was investigated and compared with that of Subtilisin Carlsberg. The amount of calcium bound to the AL-20 protease was determined to be only about 0.14 mol/mol of protease. Differential scanning calorimetry scan of the enzyme at increasing temperature showed the denaturation of the enzyme to be a two-state process with melting temperature, Tm of about 74 °C at pH 10.0, which was unaltered upon addition of calcium as well as after treatment with chelating agents. The thermodynamic parameters were nearly the same over a pH range of 7.0–10.0. Tm was reduced to 69.7 °C at pH 6.0 and 72 °C at pH 11.0. The secondary structure of the protease was unaffected during storage at 50 °C, even in the presence of 1% SDS as observed by circular dichroism. The protease activity was extremely stable in the presence of hydrogen peroxide and various sequestering agents used in detergents.
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| 10. |
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