| 1. |
- Christakopoulos, Paul, et al.
(författare)
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Antimicrobial activity of acidic xylo-oligosaccharides produced by family 10 and 11 endoxylanases
- 2003
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Ingår i: International Journal of Biological Macromolecules. - 0141-8130 .- 1879-0003. ; 31:4-5, s. 171-175
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Tidskriftsartikel (refereegranskat)abstract
- Acidic oligosaccharides were obtained from birchwood xylan by treatment with a Thermoascus aurantiacus family 10 and a Sporotrichum thermophile family 11 endoxylanases. The main difference between the products liberated by xylanases of family 10 and 11 concerned the length of the products containing 4-O-methyl-d-glucuronic acid. The xylanase from T. aurantiacus liberate from glucuronoxylan an aldotetrauronic acid as the shortest acidic fragment in contrast with the enzyme from S. thermophile, which liberated an aldopentauronic acid. Acidic xylooligosaccharides were separated from the hydrolysate by anion-exchange and size-exclusion chromatography (SEC) and the primary structure was determined by 13C NMR spectroscopy. The acidic xylo-oligosaccharides were tested against three Gram-positive and three Gram-negative aerobically grown bacteria, as well as against Helicobacterpylori. Aldopentauronic acid was proved more active against the Gram-positive bacteria and against H. pylori.
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| 2. |
- Christakopoulos, Paul, et al.
(författare)
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Enzymatic synthesis of trisaccharides and alkyl β-d-glucosides by the transglycosylation reaction of β-glucosidase from Fusarium oxysporum
- 1994
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 16:6, s. 331-334
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Tidskriftsartikel (refereegranskat)abstract
- Purified β-glucosidase from Fusarium oxysporum catalyses hydrolysis and transglycosylation reactions. By utilizing the transglycosylation reaction, trisaccharides and alkyl β-d-glucosides were synthesized under optimal conditions in the presence of various disaccharides and alcohols. The yields of trisaccharides and alkyl β-d-glucosides were 22–37% and 10–33% of the total sugar, respectively. The enzyme retained 70–80% of its original activity in the presence of 25% (w/v) methanol, ethanol and propanol. Thus, β-glucosidase from F. oxysporum appears to be an ideal enzyme for the synthesis of useful trisaccharides and alkyl β-d-glucosides.
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| 3. |
- Makropoulou, M., et al.
(författare)
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Factors affecting the specificity of beta-glucosidase from Fusarium oxysporum in enzymatic synthesis of alkyl-beta-D-glucosides
- 1998
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Ingår i: International Journal of Biological Macromolecules. - 0141-8130 .- 1879-0003. ; 22:2, s. 97-101
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Tidskriftsartikel (refereegranskat)abstract
- Factors affecting the specificity of β-glucosidase from Fusarium oxysporum in enzymatic synthesis of alkyl-β-d-glucosidesFusarium oxysporumβ-glucosidase has been used to catalyze the production of alkyl-β-d-glucosides from various disaccharides, based on the transglucosylation reaction, in the presence of primary, secondary and tertiary alcohols as glucosyl acceptors. Primary alcohols were found to be the best acceptors. The influence of the glucosyl donor concentration, as well as the enzyme specificity towards the cleaved glucosidic bond and the aglucone part of the donor, have also been investigated. The enzyme does not exhibit regiospecificity and seems to be unspecific towards the aglucone part. The specificity of the β linkage has been confirmed by proton nuclear magnetic resonance (1H NMR) analysis.
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| 4. |
- Rosdahl, Hans, et al.
(författare)
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A microdialysis method for the in situ investigation of the action of large peptide molecules in human skeletal muscle : detection of local metabolic effects of insulin.
- 2000
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 28:1, s. 69-73
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of using microdialysis catheters with a large pore size dialysis membrane (100 kDa) to investigate the action of macromolecules perfused into the interstitial space of peripheral tissues was explored. This was made possible by increasing the colloid osmotic pressure of the perfusate with 40 g/l of dextran-70 to prevent perfusate loss across the dialysis membranes. Microdialysis catheters were inserted into the quadriceps femoris muscle of 13 human subjects. With different perfusion flow rates (1. 33, 0.66, 0.33 and 0.16 microl/min) the recorded concentrations of glucose, lactate, and urea were in agreement with values previously obtained using a conventional membrane with a smaller pore size (20 kDa) [Rosdahl H, Hamrin K, Ungerstedt U, Henriksson. J Am J Physiol 1998;274:E936-45.]. When insulin was added to the perfusate, the concentration of glucose was significantly reduced, indicating that insulin diffuses across the dialysis membrane and has cellular effects that can be simultaneously recorded. The present findings are the first documentation on the use of microdialysis to study the local metabolic action of large peptide molecules in human tissues and may open new avenues for in-vivo metabolic research.
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| 5. |
- Sanakis, Y., et al.
(författare)
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Catechol 1,2-dioxygenase from Pseudomonas putida in organic media : an electron paramagnetic resonance study
- 2003
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Ingår i: International Journal of Biological Macromolecules. - 0141-8130 .- 1879-0003. ; 33:1-3, s. 101-106
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Tidskriftsartikel (refereegranskat)abstract
- The ability of an isolated isozyme of catechol 1,2-dioxygenase from Pseudomonas putida DSM 437 to function in a non-aqueous environment was investigated. The lyophilized enzyme is able to keep its catalytic function catalyzing the oxidation of catechol in n-hexane. Electron paramagnetic resonance (EPR) spectroscopy at liquid helium temperatures was applied to compare the properties of the non-heme iron of the enzyme in the organic solvent and in the aqueous solution. The catalytic performance of the enzyme in the organic solvent is correlated with the spectroscopic properties of the non-heme iron.
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| 6. |
- Vardakou, Maria, et al.
(författare)
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Mode of action of family 10 and 11 endoxylanases on water-unextractable arabinoxylan
- 2003
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Ingår i: International Journal of Biological Macromolecules. - 0141-8130 .- 1879-0003. ; 33:1-3, s. 129-134
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Tidskriftsartikel (refereegranskat)abstract
- Microbial endo-β-1,4-xylanases (EXs, EC 3.2.1.8) belonging to glycanase families 10 and 11 differ in their action on water-unextractable arabinoxylan (WU-AX). WU-AX was incubated with different levels of a Thermoascus aurantiacus family 10 and a Sporotrichum thermophile family 11 endoxylanases. At 10 g l−1 arabinoxylan, enzyme concentrations (KE values) needed to obtain half-maximal hydrolysis rates (Vmax values) were 4.4 nM for the xylanase from T. aurantiacus and 7.1 nM for the xylanase from S. thermophile. Determination of Vmax/KE revealed that the family 10 enzyme hydrolysed two times more efficiently WU-AX than the family 11 enzyme. Molecular weights of the products formed were assessed and separation of feruloyl-oligosaccharides was achieved by anion-exchange and size-exclusion chromatography (SEC). The main difference between the feruloylated products by xylanases of family 10 and 11 concerned the length of the products containing feruloyl-arabinosyl substitution. The xylanase from T. aurantiacus liberated from WU-AX a feruloyl arabinoxylodisaccharide (FAX2) as the shortest feruloylated fragment in contrast with the enzyme from S. thermophile, which liberated a feruloyl arabinoxylotrisaccharide (FAX3). These results indicated that different factors govern WU-AX breakdown by the two endoxylanases.
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| 7. |
- Abdollahi, Mehdi, 1985, et al.
(författare)
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Carboxymethyl cellulose-agar biocomposite film activated with summer savory essential oil as an antimicrobial agent
- 2019
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 126, s. 561-568
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Tidskriftsartikel (refereegranskat)abstract
- Carboxymethyl cellulose (CMC)-agar biocomposite film was developed by a solvent casting method and the effects of summer savory essential oil (SSEO) at 0.5, 1.0 and 1.5% v/v on antimicrobial, microstructural, mechanical and optical properties as well as water sensitivity of the films were studied. Results showed that incorporation of SSEO into the biocomposite film developed active films with good antimicrobial agent growth inhibition activity against Gram-positive bacteria (S. aureus, B. cereus and L. monocytogenes) and less powerfully against Gram-negative bacteria (E. coli). Addition of the SSEO at 1.0 and 1.5% increased microstructural heterogeneity of the films and hence significantly (p < 0.05) increased water vapor permeability of the films while reducing their tensile strength. In contrast, mechanical flexibility and surface hydrophobicity of the films was significantly (p < 0.05) improved as a function of SSEO addition. The active films showed substantially lower swelling ratio compared to the CMC-agar film when 1.5% SSEO was added, but the transparency of the films was reduced. Finally, the results showed that SSEO can act as an antimicrobial agent in combination with CMC-agar film. However, it modifies properties of the film depending on the applied concentration.
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| 8. |
- Abdollahi, Mehdi, 1985, et al.
(författare)
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Reducing water sensitivity of alginate bio-nanocomposite film using cellulose nanoparticles
- 2013
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 54:1, s. 166-173
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Tidskriftsartikel (refereegranskat)abstract
- A bio-based nanocomposite was developed by incorporation of cellulose nanoparticles (CN) obtained from sulfuric acid hydrolysis into alginate biopolymer using solution casting method. The effect of CN loading content (1, 3, 5 and 10 wt%) on microstructural, physical, mechanical and optical properties of the nanocomposites were characterized. The results showed that water solubility and water vapor permeability of the nanocomposites decreased by about 40% and 17%, respectively, upon increasing the CN content to 10%. In addition, the crystalline structure of the CN increased surface hydrophobicity of the alginate film by about 98%. The tensile strength value of the composite films increased from 18.03 to 22.4 MPa with increasing NC content from 0 to 5%; but, it decreased with further increase of the filler content. Nevertheless, film transparency decreased with CN incorporation, especially in high level (10%), which suggested the occurrence of partial agglomeration of the fillers at 10% that coincided with microstructural and mechanical results.
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| 9. |
- Agustin, Melissa B., et al.
(författare)
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Enzymatic crosslinking of lignin nanoparticles and nanocellulose in cryogels improves adsorption of pharmaceutical pollutants
- 2024
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier BV. - 0141-8130 .- 1879-0003. ; 266
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Tidskriftsartikel (refereegranskat)abstract
- Pharmaceuticals, designed for treating diseases, ironically endanger humans and aquatic ecosystems as pollutants. Adsorption-based wastewater treatment could address this problem, however, creating efficient adsorbents remains a challenge. Recent efforts have shifted towards sustainable bio-based adsorbents. Here, cryogels from lignin-containing cellulose nanofibrils (LCNF) and lignin nanoparticles (LNPs) were explored as pharmaceuticals adsorbents. An enzyme-based approach using laccase was used for crosslinking instead of fossil-based chemical modification. The impact of laccase treatment on LNPs alone produced surface-crosslinked water-insoluble LNPs with preserved morphology and a hemicellulose-rich, water-soluble LNP fraction. The water-insoluble LNPs displayed a significant increase in adsorption capacity, up to 140 % and 400 % for neutral and cationic drugs, respectively. The crosslinked cryogel prepared by one-pot incubation of LNPs, LCNF and laccase showed significantly higher adsorption capacities for various pharmaceuticals in a multi-component system than pure LCNF or unmodified cryogels. The crosslinking minimized the leaching of LNPs in water, signifying enhanced binding between LNPs and LCNF. In real wastewater, the laccase-modified cryogel displayed 8–44 % removal for cationic pharmaceuticals. Overall, laccase treatment facilitated the production of bio-based adsorbents by improving the deposition of LNPs to LCNF. Finally, this work introduces a sustainable approach for engineering adsorbents, while aligning with global sustainability goals.
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| 10. |
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