A p.m.r. study of the composition and sequence of uronate residues in alginates

Grasdalen, Hans; Lársen, Bjørn; Smidsrød, Olav

doi:10.1016/s0008-6215(00)84051-3

Cited by 472 publications

(262 citation statements)

References 12 publications

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“…The total absence of G blocks in all the samples analysed and the apparent independence of composition and Ca 2 + levels ( The absence of G blocks was established using a standard IH-n.m.r. procedure (Grasdalen et al 1979) developed for the analysis of algal alginates. Quantitation of each uronic acid and block type was calculated from the integrals of the resonances in the downfield region of the spectra (Figs 3a-3d).…”

Section: Discussionmentioning

confidence: 99%

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Composition of Alginate Synthesized during the Growth Cycle of Pseudomonas aeruginosa

Annison

Couperwhite²

1987

Aust. Jnl. Of Bio. Sci.

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A mucoid P. aeruginosa isolated from the sputum of a cystic fibrosis patient was grown in batch culture on a complex medium. During the growth cycle the amount of alginate produced was estimated and its composition was determined by proton magnetic resonance (IH-n.m.r) spectroscopy. Exopolysaccharide production occurred mainly during the exponential phase of growth. The alginate samples isolated varied little in composition and were characterized by being highly acetylated, high mannuronate (0.83 -0.93 mole fraction) polymers. Guluronate was present only within heteropolymeric regions of the polysaccharides which all displayed a complete absence of polyguluronate. Ca 2 + ion supplementation of the medium was not observed to increase the levels of guluronate in the algi nates produced.

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Section: Discussionmentioning

confidence: 99%

“…The mole fractions of mannuronic acid, guluronic acid, polymannuronic acid, polyguluronic acid blocks and mixed blocks were determined from IH-n.m.r. spectra using the method of Grasdalen et al (1979).…”

Section: Ih -Nm T Analysismentioning

confidence: 99%

Composition of Alginate Synthesized during the Growth Cycle of Pseudomonas aeruginosa

Annison

Couperwhite²

1987

Aust. Jnl. Of Bio. Sci.

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“…The molecular compositions of LVG and LVM were provided by the supplier, but the composition of S-alginate was quantified for this study by a proton 1 H-NMR spectroscopy method. 47 LVM, LVG, and S-alginates contained 43%, 68%, and 68% guluronic acid residues, respectively. Reagents, including the neurobasal medium, DMEM/F12 (1:1), B-27 supplement, Dulbecco's Phosphate-Buffered Saline without Ca 2 + and Mg 2 + , and trypsin/EDTA solution were all purchased from Invitrogen (Darmstadt, Germany).…”

Section: Materials and Reagentsmentioning

confidence: 99%

Swelling and Mechanical Properties of Alginate Hydrogels with Respect to Promotion of Neural Growth

Matyash

Despang²,

Ikonomidou³

et al. 2014

Tissue Engineering Part C: Methods

112

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Soft alginate hydrogels support robust neurite outgrowth, but their rapid disintegration in solutions of high ionic strength restricts them from long-term in vivo applications. Aiming to enhance the mechanical stability of soft alginate hydrogels, we investigated how changes in pH and ionic strength during gelation influence the swelling, stiffness, and disintegration of a three-dimensional (3D) alginate matrix and its ability to support neurite outgrowth. Hydrogels were generated from dry alginate layers through ionic crosslinks with Ca 2 + ( £ 10 mM) in solutions of low or high ionic strength and at pH 5.5 or 7.4. High-and low-viscosity alginates with different molecular compositions demonstrated pH and ionic strength-independent increases in hydrogel volume with decreases in Ca 2 + concentrations from 10 to 2 mM. Only soft hydrogels that were synthesized in the presence of 150 mM of NaCl (Ca-alginate NaCl ) displayed long-term volume stability in buffered physiological saline, whereas analogous hydrogels generated in NaCl-free conditions (Ca-alginate) collapsed. The stiffnesses of Ca-alginate NaCl hydrogels elevated from 0.01 to 19 kPa as the Ca 2 + -concentration was raised from 2 to 10 mM; however, only Ca-alginate NaCl hydrogels with an elastic modulus £ 1.5 kPa that were generated with £ 4 mM of Ca 2 + supported robust neurite outgrowth in primary neuronal cultures. In conclusion, soft Ca-alginate NaCl hydrogels combine mechanical stability in solutions of high ionic strength with the ability to support neural growth and could be useful as 3D implants for neural regeneration in vivo.

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“…The 200 MHz 'H-NMR spectra were recorded at 90 "C with a Bruker AC 200 instrument. The monomeric composition and the diad frequencies were determined from the 'H spectra according to the procedure established by Grasdalen et al (1979). M, determination.…”

Section: Determination Of Uronic Acid Frequencies Of Alginatesmentioning

confidence: 99%

Alginate from Pseudomonas fluorescens and P. putida: production and properties

et al. 1994

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The alginate-like polysaccharides synthesized by Pseudomonas fluorescens and Pseudomonas putida have been prepared from batch cultures grown with glucose and fructose as carbon substrates. Despite the different methods of catabolism of the two substrates and synthesis of the alginate precursors, both strains produced polysaccharides which were consistent in their composition of mannuronic and guluronic acids and in the frequency of occurrence of dimers of D-mannuronic acid. All preparations lacked homooligomeric sequences of L-guluronic acid and were highly acetylated (12-21 %).In all the culture conditions tested, polysaccharide production was growthassociated and maximum M, was obtained after 48 h growth; older cultures contained material of progressively lower M, . This was ascribed to the degradative activity of alginate lyases which were detected intracellularly in both species and are presumably released by cell lysis. A t 72 h, alginate from P. putida grown on either substrate had an M, of only 34000-38500, whereas the product from P. fluorescens grown on fructose had an M, of 300000 and that from glucose-grown cultures an M, of 72000. Keywords : alginate, Pseudomonas pzltida, Pseudomonas juorescens INTRODUCTIONAlginic acid is a linear copolymer of 1+4-linked /?-Dmannuronic acid and its C-5 epimer a-L-guluronic acid. Commercially available alginates are currently isolated from marine algae such as Laminaria and Macroystis. The rheological and gel-forming properties of alginate which have led to its commercial exploitation depend on the Mr and the distribution and relative content of the two monomers along the polymeric chain. The main industrial applications of alginates are as thickeners, stabilizers, gelling agents, emulsifiers, surface-coating agents, synthetic films and fibres (Sutherland, 1991 Several species of bacteria of the genera Aptobacter and Pseudomonas produce an exopolysaccharide (EPS) which bears strong resemblance to the algal product, except that the molecule is partially acetylated. Thus, the utilization of bacterial strains could be extended to the production of alginate, as has been possible for other polysaccharides of economic importance such as gellan, hyaluronic acid and xanthan, which are obtained through bacterial fermentation. Polymers of microbial origin offer several advantages, including batch-to-batch homogeneity, lack of seasonal variation, and the fact that such features as Mr, composition and yield can be partially controlled by altering the culture conditions (Sutherland, 1987 ; Obika e t al., 1993) or by genetic manipulation of the producing strains (Martins & Sa-Correia, 1991 ; Gacesa & Goldberg, 1 992).The alginate production of Pseudomoms aerzlginosa has been the subject of intense study, since the production of the polymer appears to play a crucial role in lung infections found in cystic fibrosis patients (Gacesa & Russell, 1990). These studies have revealed valuable information o n the genetics and mechanisms of bacterial alginate production (e.g. Martin et a/.,...

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A p.m.r. study of the composition and sequence of uronate residues in alginates

Cited by 472 publications

References 12 publications

Composition of Alginate Synthesized during the Growth Cycle of Pseudomonas aeruginosa

Composition of Alginate Synthesized during the Growth Cycle of Pseudomonas aeruginosa

Swelling and Mechanical Properties of Alginate Hydrogels with Respect to Promotion of Neural Growth

Alginate from Pseudomonas fluorescens and P. putida: production and properties

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