| 1. |
- Christakopoulos, Paul, et al.
(författare)
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Synthesis of biological active compounds using carbohydrate esterases as biocatalysts
- 2014
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Ingår i: New Biotechnology. - : Elsevier BV. - 1871-6784 .- 1876-4347. ; 31:Supplement, s. S90-S91
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Tidskriftsartikel (refereegranskat)abstract
- Various fungal and bacterial carbohydrate esterases represent appealing biocatalysts that have the ability not only to deconstruct plant biomass but also to modify compounds with a potential use in food, cosmetic and pharmaceutical industries. Feruloyl esterases (FAEs, E.C. 3.1.1.73) have been proved promising candidates for the enzymatic synthesis of antioxidants allowing more flexible process configurations. Among the advantages they provide are use of lower temperatures (50-60 °C) comparing to the counterpart chemical process (150οC), one step production of one product instead of mixtures and no need of by-product and catalyst residues removal in order to produce clean and high quality substances. Glucuronoyl esterase (GE) synthetic ability needs to be explored towards the production of alkyl branched glucuronic acid derivatives which are non-ionic surfactants and have good surface properties, including biodegradability. In addition, due to their tastelessness, non skin-irritation and non toxicity, these bioactive compounds find diverse uses in the cosmetic and pharmaceutical industries.Aim of this work is the development of competitive and eco-friendly bioconversions based on transesterification reactions catalyzed by FAEs and GEs, for the production of molecules with antioxidant activity, such as phenolic fatty and sugar esters. The synthesis of four biological active compounds (prenyl ferulate, prenyl caffeate, 5-O-(trans-feruloyl)-arabinofuranose, and glyceryl ferulate) was evaluated using recombinant FAEs from Myceliopthora thermophila and Fusarium oxysporum, while the synthesis of benzyl D-glucuronate and prenyl-D-glucuronate was evaluated using recombinant GEs from M. thermophila. All reactions were carried out in ternary systems of n-hexane/alcohol/water forming surfactantless microemulsions.
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| 2. |
- Moukouli, Maria, et al.
(författare)
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Cloning and optimized expression of a GH-11 xylanase from Fusarium oxysporum in Pichia pastoris
- 2011
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Ingår i: New Biotechnology. - : Elsevier BV. - 1871-6784 .- 1876-4347. ; 28:4, s. 369-374
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Tidskriftsartikel (refereegranskat)abstract
- The endo-1,4-beta-xylanase gene xyn11a from Fusarium oxysporum, member of the fungal glycosyl hydrolase (GH) family 11, was cloned and expressed in Pichia pastoris. The mature xylanase gene, which generates after the excision of one intron and the secreting signal peptide, was placed under the control of an alcohol oxidase promoter (AOX1) in the plasmid pPICZ alpha C. The final construction was integrated into the genome of the methylotrophic yeast P. pastoris X33 and the ability to produce xylanase activity was evaluated in flask cultures. Recombinant P. pastoris efficiently secreted xylanase into the medium and produced high level of enzymatic activity (110 U/ml) after 216 hours of growth, under methanol induction. To achieve higher enzyme production, the influence of initial pH, methanol concentration, agitation and flask design was evaluated. Under optimum culture conditions, production of the recombinant xylanase increased by 50%, reaching a final yield of 170 U/ml, underpinning aeration as the most important factor in improving enzyme production.
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| 3. |
- Zerva, Anastasia, et al.
(författare)
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A novel thermophilic laccase-like multicopper oxidase from Thermothelomyces thermophila and its application in the oxidative cyclization of 2′,3,4-trihydroxychalcone
- 2019
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Ingår i: New Biotechnology. - : Elsevier. - 1871-6784 .- 1876-4347. ; 49, s. 10-18
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Tidskriftsartikel (refereegranskat)abstract
- Laccase-like multicopper oxidases (LMCOs) are a heterogeneous group of oxidases, acting mainly on phenolic compounds and which are widespread among many microorganisms, including Basidiomycetes and Ascomycetes. Here, we report the cloning, heterologous expression, purification and characterization of a novel LMCO from the thermophilic fungus Thermothelomyces thermophila. The 1953 bp lmco gene sequence comprises of 3 exons interrupted by 2 introns and according to the LccED database the translated sequence belongs to superfamily 6 of multicopper oxidases. After removal of the introns, the gene was transformed into Pichia pastoris, under the control of the alcohol oxidase (AOX1) promoter. The heterologous enzyme was purified with an apparent molecular weight of 80 kDa. TtLMCO1 displayed optimum activity at pH 4 and 50 °C and appeared thermostable up to 50 °C. A variety of phenolic compounds were oxidized by TtLMCO1, including standard laccase substrates such as ABTS and 2,6 dimethoxyphenol. The UV/Vis spectrum of purified TtLMCO1 indicates that it belongs to yellow laccase-like oxidases. The enzyme was used for the bioconversion of 2′,3,4-trihydroxychalcone to 3′,4′-dihydroxy-aurone, a bioactive aurone recently shown to possess inhibitory activity against several isoforms of the histone deacetylase complex (HDAC). Overall, the thermophilic yellow LMCO TtLMCO1 presents a number of superior properties with potential use in industrial biocatalysis.
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