scholarly journals Autocatalytic Fractionation of Wood Hemicelluloses: Modeling of Multistage Operation

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 337
Author(s):  
Mar López ◽  
Valentín Santos ◽  
Juan Carlos Parajó
Keyword(s):  
Liquid Phase ◽  
High Performance ◽  
Amperometric Detection ◽  
Anion Exchange Chromatography ◽  
Optimal Recovery ◽  
Exchange Chromatography ◽  
Size Exclusion ◽  
Reaction Products ◽  
Flight Mass Spectrometry ◽  
Kinetic Coefficients

Eucalyptus globulus wood samples were treated with hot, compressed water (autohydrolysis) in consecutive stages under non-isothermal conditions in order to convert the hemicellulose fraction into soluble compounds through reactions catalyzed by in situ generated acids. The first stage was a conventional autohydrolysis, and liquid phase obtained under conditions leading to an optimal recovery of soluble saccharides was employed in a new reaction (second crossflow stage) using a fresh wood lot, in order to increase the concentrations of soluble saccharides. In the third crossflow stage, the best liquid phase from the second stage was employed to solubilize the hemicelluloses from a fresh wood lot. The concentration profiles determined for the soluble saccharides, acids, and furans present in the liquid phases from the diverse crossflow stages were employed for kinetic modeling, based on pseudohomogeneous reactions and Arrhenius-type dependence of the kinetic coefficients on temperature. Additional characterization of the reaction products by High Pressure Size Exclusion Chromatography, High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection, and Matrix Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry provided further insight on the properties of the soluble saccharides present in the various reaction media.

scholarly journals Altered immunoglobulin G glycosylation in patients with isolated hyperprolactinaemia

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0247805
Author(s):  
Daniel Hirschberg ◽  
Bertil Ekman ◽  
Jeanette Wahlberg ◽  
Eva Landberg
Keyword(s):  
Immunoglobulin G ◽  
High Performance ◽  
Amperometric Detection ◽  
Peptide Hormone ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Flight Mass Spectrometry ◽  
Healthy Control ◽  
Altered Immune Response ◽  
And Gender

Prolactin is a peptide hormone produced in the anterior pituitary, which increase in several physiological and pathological situations. It is unclear if hyperprolactinaemia may affect glycosylation of immunoglobulin G (IgG). Twenty-five patients with hyperprolactinemia and 22 healthy control subjects were included in the study. The groups had similar age and gender distribution. A panel of hormonal and haematological analyses, creatinine, glucose, liver enzymes and immunoglobulins were measured by routine clinical methods. IgG was purified from serum by Protein G Sepharose. Sialic acid was released from IgG by use of neuraminidase followed by quantification on high performance anion-exchange chromatography with pulsed amperometric detection. Tryptic glycopeptides of IgG was analysed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Hormone and immunoglobulin levels were similar in the two groups, except for IgA and prolactin. Significantly higher IgG1 and IgG2/3 galactosylation was found in the patient group with hyperprolactinaemia compared to controls. (A significant correlation between prolactin and IgG2/3 galactosylation (Rs 0.61, p<0.001) was found for samples with prolactin values below 2000 mIU/L. The relative amount of sialylated and bisecting glycans on IgG did not differ between patients and controls. The four macroprolactinaemic patients showed decreased relative amount of bisecting IgG2/3 glycans. Hyperprolactinaemia was found to be associated with increased galactosylation of IgG1and IgG2/3. This may have impact on IgG interactions with Fc-receptors, complement and lectins, and consequently lead to an altered immune response.

scholarly journals Mode of action and subsite studies of the guluronan block-forming mannuronan C-5 epimerases AlgE1 and AlgE6

2006 ◽  
Vol 395 (2) ◽  
pp. 319-329 ◽  
Author(s):  
Synnøve Holtan ◽  
Per Bruheim ◽  
Gudmund Skjåk-Bræk
Keyword(s):  
High Performance ◽  
Azotobacter Vinelandii ◽  
Block Size ◽  
Amperometric Detection ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Size Exclusion ◽  
Mannuronic Acid ◽  
Enzyme Degradation ◽  
Exclusion Chromatography

AlgE1, AlgE5 and AlgE6 are members of a family of mannuronan C-5 epimerases encoded by the bacterium Azotobacter vinelandii, and are active in the biosynthesis of alginate, where they catalyse the post-polymerization conversion of β-D-mannuronic acid (M) residues into α-L-guluronic acid residues (G). All enzymes show preference for introducing G-residues neighbouring a pre-existing G. They also have the capacity to convert single M residues flanked by G, thus ‘condensing’ G-blocks to form almost homopolymeric guluronan. Analysis of the length and distribution of G-blocks based on specific enzyme degradation combined with size-exclusion chromatography, electrospray ionization MS, HPAEC–PAD (high-performance anion-exchange chromatography and pulsed amperometric detection), MALDI (matrix-assisted laser-desorption ionization)-MS and NMR revealed large differences in block length and distribution generated by AlgE1 and AlgE6, probably reflecting their different degree of processivity. When acting on polyMG as substrates, AlgE1 initially forms only long homopolymeric G-blocks >50, while AlgE6 gives shorter blocks with a broader block size distribution. Analyses of the AlgE1 and AlgE6 subsite specificities by the same methodology showed that a mannuronan octamer and heptamer respectively were the minimum substrate chain lengths needed to accommodate enzyme activities. The fourth M residue from the non-reducing end is epimerized first by both enzymes. When acting on MG-oligomers, AlgE1 needed a decamer while AlgE6 an octamer to accommodate activity. By performing FIA (flow injection analysis)-MS on the lyase digests of epimerized and standard MG-oligomers, the M residue in position 5 from the non-reducing end was preferentially attacked by both enzymes, creating an MGMGGG-sequence (underlined and boldface indicate the epimerized residue).

scholarly journals Isolation of Reaction Products Resulting from Heat-Induced Degradation of Inulin

2009 ◽  
Vol 27 (Special Issue 1) ◽  
pp. S166-S168 ◽  
Author(s):  
K. Trabs ◽  
N. Kasprick ◽  
T. Henle
Keyword(s):  
High Performance ◽  
Amperometric Detection ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Flash Chromatography ◽  
Bakery Products ◽  
Reaction Products ◽  
Pulsed Amperometric Detection ◽  
Dfa Iii ◽  
Final Purification

From inulin which had been heated for 30 min at 200°C, four di-D-fructose dianhydrides (DFDAs) were isolated using flash chromatography and final purification by semipreparative HPLC, followed by identification via NMR spectroscopy. The DFDAs &alpha;-D-Fru<I>f</I>-1,2':2,3'-β-D-Fruf (DFA III), &alpha;-D-Fru<I>f</I>-1,2':2,1'-β-D-Fru<I>f</I> (DFA I), &alpha;-D-Fru<I>f</I>-1,2':2,1'-&alpha;-D-Fru<I>f</I> (DFA VII) and β-D-Fru<I>f</I>-1,2´:2,1´-β-D-Fru<I>f</I> were identified. The yield of the isolated DFDAs varied depending on the DP of the used inulin. Using the isolated DFDAs as reference compounds, quantification of the disaccharides in commercial bakery products via high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was possible.

scholarly journals Enzymatic Synthesis and Characterization of Different Families of Chitooligosaccharides and Their Bioactive Properties

2021 ◽  
Vol 11 (7) ◽  
pp. 3212
Author(s):  
Noa Miguez ◽  
Peter Kidibule ◽  
Paloma Santos-Moriano ◽  
Antonio O. Ballesteros ◽  
Maria Fernandez-Lobato ◽  
...  
Keyword(s):  
High Performance ◽  
Chemical Characterization ◽  
Amperometric Detection ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Enzymatic Production ◽  
Bioactive Properties ◽  
Substrate Properties ◽  
Chitin Hydrolysis

Chitooligosaccharides (COS) are homo- or hetero-oligomers of D-glucosamine (GlcN) and N-acetyl-D-glucosamine (GlcNAc) that can be obtained by chitosan or chitin hydrolysis. Their enzymatic production is preferred over other methodologies (physical, chemical, etc.) due to the mild conditions required, the fewer amounts of waste and its efficiency to control product composition. By properly selecting the enzyme (chitinase, chitosanase or nonspecific enzymes) and the substrate properties (degree of deacetylation, molecular weight, etc.), it is possible to direct the synthesis towards any of the three COS types: fully acetylated (faCOS), partially acetylated (paCOS) and fully deacetylated (fdCOS). In this article, we review the main strategies to steer the COS production towards a specific group. The chemical characterization of COS by advanced techniques, e.g., high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and MALDI-TOF mass spectrometry, is critical for structure–function studies. The scaling of processes to synthesize specific COS mixtures is difficult due to the low solubility of chitin/chitosan, the heterogeneity of the reaction mixtures, and high amounts of salts. Enzyme immobilization can help to minimize such hurdles. The main bioactive properties of COS are herein reviewed. Finally, the anti-inflammatory activity of three COS mixtures was assayed in murine macrophages after stimulation with lipopolysaccharides.

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