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Nøkling-Eide K, Aachmann FL, Tøndervik A, Arlov Ø, Sletta H. In-process epimerisation of alginates from Saccharina latissima, Alaria esculenta and Laminaria hyperborea. Carbohydr Polym 2024; 325:121557. [PMID: 38008481 DOI: 10.1016/j.carbpol.2023.121557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 10/17/2023] [Accepted: 11/01/2023] [Indexed: 11/28/2023]
Abstract
Alginates are valued in many industries, due to their versatile properties. These polysaccharides originate from brown algae (Phaeophyceae) and some bacteria of the Azotobacter and Pseudomonas genera, consisting of 1 → 4 linked β-d-mannuronic acid (M), and its C5-epimer α-l-guluronic acid (G). Several applications rely on a high G-content, which confers good gelling properties. Because of its high natural G-content (FG = 0.60-0.75), the alginate from Laminaria hyperborea (LH) has sustained a thriving industry in Norway. Alginates from other sources can be upgraded with mannuronan C-5 epimerases that convert M to G, and this has been demonstrated in many studies, but not applied in the seaweed industry. The present study demonstrates epimerisation directly in the process of alginate extraction from cultivated Saccharina latissima (SL) and Alaria esculenta (AE), and the lamina of LH. Unlike conventional epimerisation, which comprises multiple steps, this in-process protocol can decrease the time and costs necessary for alginate upgrading. In-process epimerisation with AlgE1 enzyme enhanced G-content and hydrogel strength in all examined species, with the greatest effect on SL (FG from 0.44 to 0.76, hydrogel Young's modulus from 22 to 34 kPa). As proof of concept, an upscaled in-process epimerisation of alginate from fresh SL was successfully demonstrated.
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Affiliation(s)
- Katharina Nøkling-Eide
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Richard Birkelands vei 3 B, 7034 Trondheim, Norway; Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælands vei 6/8, 7491 Trondheim, Norway.
| | - Finn Lillelund Aachmann
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælands vei 6/8, 7491 Trondheim, Norway
| | - Anne Tøndervik
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Richard Birkelands vei 3 B, 7034 Trondheim, Norway
| | - Øystein Arlov
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Richard Birkelands vei 3 B, 7034 Trondheim, Norway
| | - Håvard Sletta
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Richard Birkelands vei 3 B, 7034 Trondheim, Norway
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Mannuronate C-5 epimerases and their use in alginate modification. Essays Biochem 2023; 67:615-627. [PMID: 36876890 DOI: 10.1042/ebc20220151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 02/01/2023] [Accepted: 02/02/2023] [Indexed: 03/07/2023]
Abstract
Alginate is a polysaccharide consisting of β-D-mannuronate (M) and α-L-guluronate (G) produced by brown algae and some bacterial species. Alginate has a wide range of industrial and pharmaceutical applications, owing mainly to its gelling and viscosifying properties. Alginates with high G content are considered more valuable since the G residues can form hydrogels with divalent cations. Alginates are modified by lyases, acetylases, and epimerases. Alginate lyases are produced by alginate-producing organisms and by organisms that use alginate as a carbon source. Acetylation protects alginate from lyases and epimerases. Following biosynthesis, alginate C-5 epimerases convert M to G residues at the polymer level. Alginate epimerases have been found in brown algae and alginate-producing bacteria, predominantly Azotobacter and Pseudomonas species. The best characterised epimerases are the extracellular family of AlgE1-7 from Azotobacter vinelandii (Av). AlgE1-7 all consist of combinations of one or two catalytic A-modules and one to seven regulatory R-modules, but even though they are sequentially and structurally similar, they create different epimerisation patterns. This makes the AlgE enzymes promising for tailoring of alginates to have the desired properties. The present review describes the current state of knowledge regarding alginate-active enzymes with focus on epimerases, characterisation of the epimerase reaction, and how alginate epimerases can be used in alginate production.
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Gaardløsa M, Lervikb A, Samsonova SA. Computational modeling of the molecular basis for the calcium-dependence of the mannuronan C-5 epimerase AvAlgE6 from Azotobacter vinelandii. Comput Struct Biotechnol J 2023; 21:2188-2196. [PMID: 37013001 PMCID: PMC10066508 DOI: 10.1016/j.csbj.2023.03.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/13/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023] Open
Abstract
The mannuronan C-5 epimerases catalyze epimerization of β-d-mannuronic acid to α-l-guluronic acid in alginate polymers. The seven extracellular Azotobacter vinelandii epimerases (AvAlgE1-7) are calcium-dependent, and calcium is essential for the structural integrity of their carbohydrate binding R-modules. Ca2+ is also found in the crystal structures of the A-modules, where it is suggested to play a structural role. In this study, the structure of the catalytic A-module of the A. vinelandii mannuronan C-5 epimerase AvAlgE6 is used to investigate the role of this Ca2+. Molecular dynamics (MD) simulations with and without calcium reveal the possible importance of the bound Ca2+ in the hydrophobic packing of β-sheets. In addition, a putative calcium binding site is found in the active site, indicating a potential direct role of this calcium in the catalysis. According to the literature, two of the residues coordinating calcium in this site are essential for the activity. MD simulations of the interaction with bound substrate indicate that the presence of a calcium ion in this binding site increases the binding strength. Further, explicit calculations of the substrate dissociation pathways with umbrella sampling simulations show and energetically higher dissociation barrier when calcium is present. The present study eludes to a putative catalytic role of calcium in the charge neutralizing first step of the enzymatic reaction. In addition to the importance for understanding these enzymes' molecular mechanisms, this could have implications for engineering strategies of the epimerases in industrial alginate processing.
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Cao S, Li L, Zhu B, Yao Z. Alginate modifying enzymes: An updated comprehensive review of the mannuronan C5-epimerases. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Tøndervik A, Aune R, Degelmann A, Piontek M, Ertesvåg H, Skjåk-Bræk G, Sletta H. Strain Construction and Process Development for Efficient Recombinant Production of Mannuronan C-5 Epimerases in Hansenula polymorpha. FRONTIERS IN PLANT SCIENCE 2022; 13:837891. [PMID: 35734252 PMCID: PMC9208277 DOI: 10.3389/fpls.2022.837891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 04/08/2022] [Indexed: 06/15/2023]
Abstract
Alginates are linear polysaccharides produced by brown algae and some bacteria and are composed of β-D-mannuronic acid (M) and α-L-guluronic acid (G). Alginate has numerous present and potential future applications within industrial, medical and pharmaceutical areas and G rich alginates are traditionally most valuable and frequently used due to their gelling and viscosifying properties. Mannuronan C-5 epimerases are enzymes converting M to G at the polymer level during the biosynthesis of alginate. The Azotobacter vinelandii epimerases AlgE1-AlgE7 share a common structure, containing one or two catalytic A-modules (A), and one to seven regulatory R-modules (R). Despite the structural similarity of the epimerases, they create different M-G patterns in the alginate; AlgE4 (AR) creates strictly alternating MG structures whereas AlgE1 (ARRRAR) and AlgE6 (ARRR) create predominantly G-blocks. These enzymes are therefore promising tools for producing in vitro tailor-made alginates. Efficient in vitro epimerization of alginates requires availability of recombinantly produced alginate epimerases, and for this purpose the methylotrophic yeast Hansenula polymorpha is an attractive host organism. The present study investigates whether H. polymorpha is a suitable expression system for future large-scale production of AlgE1, AlgE4, and AlgE6. H. polymorpha expression strains were constructed using synthetic genes with reduced repetitive sequences as well as optimized codon usage. High cell density cultivations revealed that the largest epimerases AlgE1 (147 kDa) and AlgE6 (90 kDa) are subject to proteolytic degradation by proteases secreted by the yeast cells. However, degradation could be controlled to a large extent either by co-expression of chaperones or by adjusting cultivation conditions. The smaller AlgE4 (58 kDa) was stable under all tested conditions. The results obtained thus point toward a future potential for using H. polymorpha in industrial production of mannuronan C-5 epimerases for in vitro tailoring of alginates.
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Affiliation(s)
- Anne Tøndervik
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Trondheim, Norway
| | - Randi Aune
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Trondheim, Norway
| | | | | | - Helga Ertesvåg
- Department of Biotechnology and Food Sciences, Trondheim, Norway
| | | | - Håvard Sletta
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Trondheim, Norway
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Pengyan Z, Chang L, Zhanru S, Fuli L, Jianting Y, Delin D. Genome-wide transcriptome profiling and characterization of mannuronan C5-epimerases in Saccharina japonica. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ci F, Jiang H, Zhang Z, Mao X. Properties and potential applications of mannuronan C5-epimerase: A biotechnological tool for modifying alginate. Int J Biol Macromol 2021; 168:663-675. [PMID: 33220370 DOI: 10.1016/j.ijbiomac.2020.11.123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 11/23/2022]
Abstract
Given the excellent characteristics of alginate, it is an industrially important polysaccharide. Mannuronan C5-epimerase (MC5E) is an alginate-modifying enzyme that catalyzes the conversion of β-D-mannuronate (M) to its C5 epimer α-L-guluronate (G) in alginate. Both the biological activities and physical properties of alginate are determined by M/G ratios and distribution patterns. Therefore, MC5E is regarded as a biotechnological tool for modifying and processing alginate. Various MC5Es derived from brown algae, Pseudomonas and Azotobacter have been isolated and characterized. With the rapid development of structural biology, the crystal structures and catalytic mechanisms of several MC5Es have been elucidated. It is necessary to comprehensively understand the research status of this alginate-modifying enzyme. In this review, the properties and potential applications of MC5Es isolated from different kinds of organisms are summarized and reviewed. Moreover, future research directions of MC5Es as well as strategies to enhance their properties are elucidated, highlighted, and prospected.
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Affiliation(s)
- Fangfang Ci
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China
| | - Hong Jiang
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
| | - Zhaohui Zhang
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China
| | - Xiangzhao Mao
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
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Huamani-Palomino RG, Córdova BM, Pichilingue L. ER, Venâncio T, Valderrama AC. Functionalization of an Alginate-Based Material by Oxidation and Reductive Amination. Polymers (Basel) 2021; 13:polym13020255. [PMID: 33466684 PMCID: PMC7828833 DOI: 10.3390/polym13020255] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/03/2021] [Accepted: 01/05/2021] [Indexed: 01/28/2023] Open
Abstract
This research focused on the synthesis of a functional alginate-based material via chemical modification processes with two steps: oxidation and reductive amination. In previous alginate functionalization with a target molecule such as cysteine, the starting material was purified and characterized by UV-Vis, 1H-NMR and HSQC. Additionally, the application of FT-IR techniques during each step of alginate functionalization was very useful, since new bands and spiked signals around the pyranose ring (1200–1000 cm−1) and anomeric region (1000–750 cm−1) region were identified by a second derivative. Additionally, the presence of C1-H1 of β-D-mannuronic acid residue as well as C1-H1 of α-L-guluronic acid residue was observed in the FT-IR spectra, including a band at 858 cm−1 with characteristics of the N-H moiety from cysteine. The possibility of attaching cysteine molecules to an alginate backbone by oxidation and post-reductive amination processes was confirmed through 13C-NMR in solid state; a new peak at 99.2 ppm was observed, owing to a hemiacetal group formed in oxidation alginate. Further, the peak at 31.2 ppm demonstrates the presence of carbon -CH2-SH in functionalized alginate—clear evidence that cysteine was successfully attached to the alginate backbone, with 185 μmol of thiol groups per gram polymer estimated in alginate-based material by UV-Visible. Finally, it was observed that guluronic acid residue of alginate are preferentially more affected than mannuronic acid residue in the functionalization.
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Affiliation(s)
- Ronny G. Huamani-Palomino
- Laboratorio de Investigación en Biopolímeros y Metalofármacos, Facultad de Ciencias, Escuela Profesional de Química, Universidad Nacional de Ingeniería, Av. Túpac Amaru 210, Lima 15333, Peru;
- Correspondence: (R.G.H.-P.); (A.C.V.)
| | - Bryan M. Córdova
- Laboratorio de Investigación en Biopolímeros y Metalofármacos, Facultad de Ciencias, Escuela Profesional de Química, Universidad Nacional de Ingeniería, Av. Túpac Amaru 210, Lima 15333, Peru;
| | - Elvis Renzo Pichilingue L.
- Facultad de Ciencias, Escuela de Química, Universidad Nacional de Ingeniería. Av. Túpac Amaru 210, Lima 15333, Peru;
| | - Tiago Venâncio
- Laboratório de Ressonância Magnética Nuclear, Departamento de Química, Universidade Federal de Sao Carlos, São Carlos 13565-905, São Paulo, Brazil;
| | - Ana C. Valderrama
- Laboratorio de Investigación en Biopolímeros y Metalofármacos, Facultad de Ciencias, Escuela Profesional de Química, Universidad Nacional de Ingeniería, Av. Túpac Amaru 210, Lima 15333, Peru;
- Correspondence: (R.G.H.-P.); (A.C.V.)
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Tøndervik A, Aarstad OA, Aune R, Maleki S, Rye PD, Dessen A, Skjåk-Bræk G, Sletta H. Exploiting Mannuronan C-5 Epimerases in Commercial Alginate Production. Mar Drugs 2020; 18:E565. [PMID: 33218095 PMCID: PMC7698916 DOI: 10.3390/md18110565] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/09/2020] [Accepted: 11/12/2020] [Indexed: 12/11/2022] Open
Abstract
Alginates are one of the major polysaccharide constituents of marine brown algae in commercial manufacturing. However, the content and composition of alginates differ according to the distinct parts of these macroalgae and have a direct impact on the concentration of guluronate and subsequent commercial value of the final product. The Azotobacter vinelandii mannuronan C-5 epimerases AlgE1 and AlgE4 were used to determine their potential value in tailoring the production of high guluronate low-molecular-weight alginates from two sources of high mannuronic acid alginates, the naturally occurring harvested brown algae (Ascophyllum nodosum, Durvillea potatorum, Laminaria hyperborea and Lessonia nigrescens) and a pure mannuronic acid alginate derived from fermented production of the mutant strain of Pseudomonas fluorescens NCIMB 10,525. The mannuronan C-5 epimerases used in this study increased the content of guluronate from 32% up to 81% in both the harvested seaweed and bacterial fermented alginate sources. The guluronate-rich alginate oligomers subsequently derived from these two different sources showed structural identity as determined by proton nuclear magnetic resonance (1H NMR), high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and size-exclusion chromatography with online multi-angle static laser light scattering (SEC-MALS). Functional identity was determined by minimum inhibitory concentration (MIC) assays with selected bacteria and antibiotics using the previously documented low-molecular-weight guluronate enriched alginate OligoG CF-5/20 as a comparator. The alginates produced using either source showed similar antibiotic potentiation effects to the drug candidate OligoG CF-5/20 currently in development as a mucolytic and anti-biofilm agent. These findings clearly illustrate the value of using epimerases to provide an alternative production route for novel low-molecular-weight alginates.
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Affiliation(s)
- Anne Tøndervik
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Richard Birkelands vei 3B, N-7034 Trondheim, Norway; (R.A.); (S.M.); (H.S.)
| | - Olav A. Aarstad
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, NTNU, Sem Sælands vei 6-8, N-7491 Trondheim, Norway; (O.A.A.); (G.S.-B.)
| | - Randi Aune
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Richard Birkelands vei 3B, N-7034 Trondheim, Norway; (R.A.); (S.M.); (H.S.)
| | - Susan Maleki
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Richard Birkelands vei 3B, N-7034 Trondheim, Norway; (R.A.); (S.M.); (H.S.)
| | - Philip D. Rye
- AlgiPharma AS, Industriveien 33, N-1337 Sandvika, Norway; (P.D.R.); (A.D.)
| | - Arne Dessen
- AlgiPharma AS, Industriveien 33, N-1337 Sandvika, Norway; (P.D.R.); (A.D.)
| | - Gudmund Skjåk-Bræk
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, NTNU, Sem Sælands vei 6-8, N-7491 Trondheim, Norway; (O.A.A.); (G.S.-B.)
| | - Håvard Sletta
- Department of Biotechnology and Nanomedicine, SINTEF Industry, Richard Birkelands vei 3B, N-7034 Trondheim, Norway; (R.A.); (S.M.); (H.S.)
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Gawin A, Tietze L, Aarstad OA, Aachmann FL, Brautaset T, Ertesvåg H. Functional characterization of three Azotobacter chroococcum alginate-modifying enzymes related to the Azotobacter vinelandii AlgE mannuronan C-5-epimerase family. Sci Rep 2020; 10:12470. [PMID: 32719381 PMCID: PMC7385640 DOI: 10.1038/s41598-020-68789-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 07/01/2020] [Indexed: 12/19/2022] Open
Abstract
Bacterial alginate initially consists of 1–4-linked β-D-mannuronic acid residues (M) which can be later epimerized to α-L-guluronic acid (G). The family of AlgE mannuronan C-5-epimerases from Azotobacter vinelandii has been extensively studied, and three genes putatively encoding AlgE-type epimerases have recently been identified in the genome of Azotobacter chroococcum. The three A. chroococcum genes, here designated AcalgE1, AcalgE2 and AcalgE3, were recombinantly expressed in Escherichia coli and the gene products were partially purified. The catalytic activities of the enzymes were stimulated by the addition of calcium ions in vitro. AcAlgE1 displayed epimerase activity and was able to introduce long G-blocks in the alginate substrate, preferentially by attacking M residues next to pre-existing G residues. AcAlgE2 and AcAlgE3 were found to display lyase activities with a substrate preference toward M-alginate. AcAlgE2 solely accepted M residues in the positions − 1 and + 2 relative to the cleavage site, while AcAlgE3 could accept either M or G residues in these two positions. Both AcAlgE2 and AcAlgE3 were bifunctional and could also catalyze epimerization of M to G. Together, we demonstrate that A. chroococcum encodes three different AlgE-like alginate-modifying enzymes and the biotechnological and biological impact of these findings are discussed.
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Affiliation(s)
- Agnieszka Gawin
- Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælandsvei 6/8, 7491, Trondheim, Norway
| | - Lisa Tietze
- Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælandsvei 6/8, 7491, Trondheim, Norway
| | - Olav A Aarstad
- Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælandsvei 6/8, 7491, Trondheim, Norway
| | - Finn L Aachmann
- Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælandsvei 6/8, 7491, Trondheim, Norway
| | - Trygve Brautaset
- Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælandsvei 6/8, 7491, Trondheim, Norway
| | - Helga Ertesvåg
- Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælandsvei 6/8, 7491, Trondheim, Norway.
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Omtvedt LA, Dalheim MØ, Nielsen TT, Larsen KL, Strand BL, Aachmann FL. Efficient Grafting of Cyclodextrin to Alginate and Performance of the Hydrogel for Release of Model Drug. Sci Rep 2019; 9:9325. [PMID: 31249333 PMCID: PMC6597533 DOI: 10.1038/s41598-019-45761-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 06/05/2019] [Indexed: 01/28/2023] Open
Abstract
Controlling the rate of release of molecules from a hydrogel is of high interest for various drug delivery systems and medical devices. A strategy to alter the release profiles of soluble and poorly soluble active ingredients from hydrogels can be to combine the hydrogel forming ability of alginate with the inclusion forming ability of cyclodextrins (CyD). Here, β-CyD was grafted to alginate in a three-step synthesis using periodate oxidation, reductive amination and copper(I)-catalyzed azide-alkyne cycloaddition. A grafting degree of 4.7% mol β-CyD/mol sugar residues was obtained. The grafting degree was controlled by varying the reaction parameters where the amount of linker used in reductive amination was especially influential. Ca-alginate gel beads grafted with β-CyD showed increased uptake of the model molecule methyl orange. Release experiments showed that the grafted material had a prolonged release of methyl orange and an increased total amount of released methyl orange. These results show that the β-CyD grafted alginate is still able to form a hydrogel while the grafted cyclodextrins retain their ability to form inclusion complex with methyl orange. Further testing should be done with this system to investigate capability for drug delivery applications.
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Affiliation(s)
- Line Aa Omtvedt
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU - Norwegian University of Science and Technology, N-7491, Trondheim, Norway
| | - Marianne Ø Dalheim
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU - Norwegian University of Science and Technology, N-7491, Trondheim, Norway
| | - Thorbjørn T Nielsen
- Department of Chemistry and Bioscience, Aalborg University (AAU), 9220, Aalborg, Denmark
| | - Kim L Larsen
- Department of Chemistry and Bioscience, Aalborg University (AAU), 9220, Aalborg, Denmark
| | - Berit L Strand
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU - Norwegian University of Science and Technology, N-7491, Trondheim, Norway
| | - Finn L Aachmann
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU - Norwegian University of Science and Technology, N-7491, Trondheim, Norway.
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Dalheim MØ, Omtvedt LA, Bjørge IM, Akbarzadeh A, Mano JF, Aachmann FL, Strand BL. Mechanical Properties of Ca-Saturated Hydrogels with Functionalized Alginate. Gels 2019; 5:E23. [PMID: 31010196 PMCID: PMC6631140 DOI: 10.3390/gels5020023] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/07/2019] [Accepted: 04/17/2019] [Indexed: 01/29/2023] Open
Abstract
In this work, the mechanical properties and stability of alginate hydrogels containing functionalized alginates (peptide and β-cyclodextrin) were studied. There is an increasing interest in the modification of alginates to add functions such as cell attachment and increased solubility of hydrophobic drugs, for better performance in tissue engineering and drug release, respectively. Functionalization was achieved in this study via periodate oxidation followed by reductive amination, previously shown to give a high and controllable degree of substitution. Young's modulus and the stress at rupture of the hydrogels were in general lowered when exchanging native alginate with the modified alginate. Still, the gel strength could be adjusted by the fraction of modified alginate in the mixed hydrogels as well as the degree of oxidation. No notable difference in deformation at rupture was observed while syneresis was influenced by the degree of oxidation and possibly by the nature and amount of the grafted molecules. The mixed hydrogels were less stable than hydrogels with only native alginate, and modified alginate was released from the hydrogels. Furthermore, the hydrogels in general rather disintegrated than swelled upon saline treatments.
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Affiliation(s)
- Marianne Ø Dalheim
- NOBIPOL, Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
| | - Line Aa Omtvedt
- NOBIPOL, Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
| | - Isabel M Bjørge
- Department of Chemistry, CICECO, Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Anita Akbarzadeh
- NOBIPOL, Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
| | - João F Mano
- Department of Chemistry, CICECO, Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Finn L Aachmann
- NOBIPOL, Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
| | - Berit L Strand
- NOBIPOL, Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
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Noar JD, Bruno-Bárcena JM. Azotobacter vinelandii: the source of 100 years of discoveries and many more to come. MICROBIOLOGY-SGM 2018. [PMID: 29533747 DOI: 10.1099/mic.0.000643] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Azotobacter vinelandii has been studied for over 100 years since its discovery as an aerobic nitrogen-fixing organism. This species has proved useful for the study of many different biological systems, including enzyme kinetics and the genetic code. It has been especially useful in working out the structures and mechanisms of different nitrogenase enzymes, how they can function in oxic environments and the interactions of nitrogen fixation with other aspects of metabolism. Interest in studying A. vinelandii has waned in recent decades, but this bacterium still possesses great potential for new discoveries in many fields and commercial applications. The species is of interest for research because of its genetic pliability and natural competence. Its features of particular interest to industry are its ability to produce multiple valuable polymers - bioplastic and alginate in particular; its nitrogen-fixing prowess, which could reduce the need for synthetic fertilizer in agriculture and industrial fermentations, via coculture; its production of potentially useful enzymes and metabolic pathways; and even its biofuel production abilities. This review summarizes the history and potential for future research using this versatile microbe.
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Affiliation(s)
- Jesse D Noar
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA
| | - Jose M Bruno-Bárcena
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA
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