Effects of a Biologically Relevant Antioxidant on the Dehydrogenative Polymerization of Coniferyl Alcohol

2008 ◽  
Vol 9 (12) ◽  
pp. 3378-3382 ◽  
Author(s):  
Anders Holmgren ◽  
Gunnar Henriksson ◽  
Liming Zhang
Keyword(s):  
Coniferyl Alcohol ◽  
Biologically Relevant ◽  
Dehydrogenative Polymerization

Studies on the dehydrogenative polymerizations of monolignol β-glycosides. Part 2: Horseradish peroxidase-catalyzed dehydrogenative polymerization of isoconiferin

Holzforschung ◽  
2006 ◽  
Vol 60 (5) ◽  
pp. 513-518 ◽  
Author(s):  
Yuki Tobimatsu ◽  
Toshiyuki Takano ◽  
Hiroshi Kamitakahara ◽  
Fumiaki Nakatsubo
Keyword(s):  
Horseradish Peroxidase ◽  
Water Solubility ◽  
Homogeneous System ◽  
Degree Of Polymerization ◽  
Coniferyl Alcohol ◽  
Water Soluble ◽  
Optimum Conditions ◽  
Spectroscopic Analyses ◽  
Dehydrogenation Polymer ◽  
Dehydrogenative Polymerization

Abstract Dehydrogenative polymerization of isoconiferin (IC; coniferyl alcohol γ-O-β-D-glucopyranoside) catalyzed by horseradish peroxidase (HRP) was carried out. The polymerization of IC proceeded in a homogeneous system, resulting in a water-soluble dehydrogenation polymer (IC-DHP). The degree of polymerization (DP) of IC-DHP was significantly higher than that of a standard dehydrogenative polymer (CA-DHP) obtained from coniferyl alcohol (CA) in a heterogeneous system. Under optimum conditions, the DP of IC-DHP was 44 (M n=1.5×104), whereas that for CA-DHP was only 11 (M n=3.0×103, as acetate). Spectroscopic analyses confirmed that IC-DHP has a lignin-like structure containing D-glucose moieties attached to the lignin side-chains. The D-glucose unit introduced into γ-O position of CA essentially influenced the water solubility and molecular mass of the resulting DHP.

Generation of lignin polymer models via dehydrogenative polymerization of coniferyl alcohol and syringyl alcohol via several plant peroxidases involved in lignification and analysis of the resulting DHPs by MALDI-TOF analysis

Holzforschung ◽  
2018 ◽  
Vol 72 (4) ◽  
pp. 267-274 ◽  
Author(s):  
Jun Shigeto ◽  
Hiroki Honjo ◽  
Koki Fujita ◽  
Yuji Tsutsumi
Keyword(s):  
Cell Wall ◽  
Horseradish Peroxidase ◽  
Molecular Size ◽  
Coniferyl Alcohol ◽  
Populus Alba ◽  
Polymer Formation ◽  
Polymer Models ◽  
Plant Peroxidases ◽  
Molecular Size Distribution ◽  
Dehydrogenative Polymerization

AbstractThe mechanism of lignin dehydrogenative polymerization (DHP), made by means of horseradish peroxidase (HRP), was studied in comparison with other plant peroxidases. Interestingly, HRP is efficient for guaiacyl type polymer formation (G-DHPs), but is not efficient in the case of syringyl type DHPs (S-DHPs). It was previously demonstrated that lignification-relatedArabidopsisthalianaperoxidases, AtPrx2, AtPrx25 and AtPrx71, and cationic cell-wall-bound peroxidase (CWPO-C) fromPopulus albaare successful to oxidize syringyl- and guaiacyl-type monomers and larger lignin-like molecules. This is the reason why in the present study the DHP formation by means of these recombinant peroxidases was tested, and all these enzymes were successful for formation of both G-DHP and S-DHP in acceptable yields. CWPO-C led to S-DHP molecular size distribution similar to that of isolated lignins.

Radical transfer system in the enzymatic dehydrogenative polymerization (DHP formation) of coniferyl alcohol (CA) and three dilignols

Holzforschung ◽  
2019 ◽  
Vol 73 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Yasuyuki Matsushita ◽  
Masaya Okayama ◽  
Dan Aoki ◽  
Sachie Yagami ◽  
Kazuhiko Fukushima
Keyword(s):  
Molecular Weight ◽  
Reaction Kinetics ◽  
Consumption Rate ◽  
Coniferyl Alcohol ◽  
Clear Picture ◽  
Transfer System ◽  
Radical Transfer ◽  
Dehydrodiconiferyl Alcohol ◽  
Dehydrogenative Polymerization

Abstract No clear picture has yet been elaborated concerning the mechanism of lignin growth, and thus this topic is the focus of the present paper. Namely, the enzymatic dehydrogenative polymerization (DHP formation) of coniferyl alcohol (CA, as a monolignol) and three dilignols and their reaction kinetics were investigated. The dilignols [guaiacylglycerol-β-coniferyl ether (IβO4), dehydrodiconiferyl alcohol (IIβ5), and pinoresinol (IIIββ)] and CA as a monolignol [(3-OCD3)-coniferyl alcohol (CAOCD3)] were synthesized and subjected to enzymatic DHP formation. The dilignol derived from CAOCD3 could be identified by its higher molecular weight in comparison with the starting dilignols (IβO4, IIβ5, and IIIββ). Based on the observed consumption rate of the CA and its dilignols, it was proposed that a radical transfer system exists between the dilignols, which is generated from the CA and the starting substrates.

Dehydrogenative Polymerization of Coniferyl Alcohol in Artificial Polysaccharides Matrices: Effects of Xylan on the Polymerization

2015 ◽  
Vol 63 (18) ◽  
pp. 4613-4620 ◽  
Author(s):  
Qiang Li ◽  
Keiichi Koda ◽  
Arata Yoshinaga ◽  
Keiji Takabe ◽  
Masatsugu Shimomura ◽  
...  
Keyword(s):  
Coniferyl Alcohol ◽  
Dehydrogenative Polymerization

Monolignol dehydrogenative polymerization in vitro in the presence of dioxane and a methylated β-β′ dimer model compound

Holzforschung ◽  
2008 ◽  
Vol 62 (5) ◽  
Author(s):  
Anders Holmgren ◽  
Liming Zhang ◽  
Gunnar Henriksson
Keyword(s):  
Model Compound ◽  
Coniferyl Alcohol ◽  
Enzymatic Oxidation ◽  
High Solubility ◽  
Dimer Model ◽  
Homogeneous Polymerization ◽  
Lignin Polymerization ◽  
C Nmr ◽  
Dehydrogenative Polymerization

Abstract Lignin formation is believed to occur by polymerization of resonance-stabilized monolignol radicals formed by enzymatic oxidation. Recently, different hypotheses suggested that lignin polymerization is influenced by surfaces in the cell wall which can be polysaccharides or proteins. The latter is called the proteinaceous dirigent sites/template polymerization hypothesis. According to another hypothesis, lignin itself is believed to act as a template and replicate its primary structure. In this work, dehydrogenative polymerization (DHP) of the lignin precursor coniferyl alcohol was performed in vitro in the presence and absence of pinoresinol dimethyl ether (a β-β′ dimer model). Another peculiarity of the experiments was the presence of dioxane which afforded a high solubility of the reactants. The question was whether the presence of β-β′ dimer model would change the structure of the DHP formed. The DHPs were analyzed by quantitative 13C NMR, GC-FID, and GC-MS. The dimer model as a template in the homogeneous polymerization state (in solution) did not influence the DHP structure.

Investigation of thin sections of biological standards by EDX, EELS, and Auger electron spectroscopy

1990 ◽  
Vol 48 (2) ◽  
pp. 184-185
Author(s):  
S. Lehner ◽  
H.E. Bauer ◽  
R. Wurster ◽  
H. Seiler
Keyword(s):  
Processing System ◽  
Beam Current ◽  
Beam Diameter ◽  
Thin Sections ◽  
Biologically Relevant ◽  
Energy Filtering ◽  
Low Viscosity ◽  
Carbon Foils ◽  
Electron Microscopical ◽  
Exchange Membrane

In order to compare different microanalytical techniques commercially available cation exchange membrane SC-1 (Stantech Inc, Palo Alto), was loaded with biologically relevant elements as Na, Mg, K, and Ca, respectively, each to its highest possible concentration, given by the number concentration of exchangeable binding sites (4 % wt. for Ca). Washing in distilled water, dehydration through a graded series of ethanol, infiltration and embedding in Spurr’s low viscosity epoxy resin was followed by thin sectioning. The thin sections (thickness of about 50 nm) were prepared on carbon foils and mounted on electron microscopical finder grids.The samples were analyzed with electron microprobe JXA 50A with transmitted electron device, EDX system TN 5400, and on line operating image processing system SEM-IPS, energy filtering electron microscope CEM 902 with EELS/ESI and Auger spectrometer 545 Perkin Elmer.With EDX, a beam current of some 10-10 A and a beam diameter of about 10 nm, a minimum-detectable mass of 10-20 g Ca seems within reach.

Quantification of cell-surface expressed antigenic sites with 5-nm gold markers: Getting close to biologically relevant data

1989 ◽  
Vol 47 ◽  
pp. 1050-1051
Author(s):  
Etienne de Harven ◽  
Hilary Christensen ◽  
Richard Leung ◽  
Cameron Ackerley
Keyword(s):  
Cell Surface ◽  
Human Peripheral Blood ◽  
Contour Length ◽  
Thin Sections ◽  
Gold Particles ◽  
Biologically Relevant ◽  
Transmission Electron ◽  
Entire Cell ◽  
Electron Imaging ◽  
Cell Contour

The T-derived subset of human peripheral blood normal lymphocytes has been selected as a model system to study the usefulness of 5 nm gold markers for quantification of single epitopes expressed on cell surfaces. The chosen epitopes are parts of the CD3 and CD5 molecules and can be specifically identified by hybridoma produced monoclonal antibodies (MoAbs; LEU-4 and LEU-1; Becton-Dick- inson, Mountain view, CA) . An indirect immunolabeling procedure, with goat anti-murine IgG adsorbed on the surface of 5 nm colloidal gold particles (GAM-G5, Janssen Pharmaceutica, Beerse, Belgium) has been used. Backscattered Electron Imaging (BEI) in a field emission scanning electronmicroscope (SEM) and transmission electron microscopy of thin sections of lymphocytes labeled before plastic embedding, were both used to identify and quantitate gold labeled cell surface sites, Estimating that the thickness of “silver” sections is approximately 60 nm and counting the number of gold particles on the entire cell perimeter, we calculated that, for LEU-4, the number of markers per um2 of cell surface is in the 140-160 range (Fig.l). Cell contour length measurements indicated that the surface of one lymphocyte is approximately 130-160 um2 that of a smooth sphere of identical diameter, reflecting the role of microvilli in expanding the surface area. The total number of gold labeled sites on the surface of one lymphocyte averages, therefore between 20,000 and 24,000 per cell.

Neural Network for Automatic Analysis of Motility Data

1994 ◽  
Vol 33 (01) ◽  
pp. 157-160 ◽  
Author(s):  
S. Kruse-Andersen ◽  
J. Kolberg ◽  
E. Jakobsen
Keyword(s):  
Neural Network ◽  
Muscular Activity ◽  
Recording System ◽  
Automatic Analysis ◽  
Biologically Relevant ◽  
System A ◽  
The Neural Network ◽  
Valuable Method ◽  
Motor Abnormalities ◽  
Trained Network

Abstract:Continuous recording of intraluminal pressures for extended periods of time is currently regarded as a valuable method for detection of esophageal motor abnormalities. A subsequent automatic analysis of the resulting motility data relies on strict mathematical criteria for recognition of pressure events. Due to great variation in events, this method often fails to detect biologically relevant pressure variations. We have tried to develop a new concept for recognition of pressure events based on a neural network. Pressures were recorded for over 23 hours in 29 normal volunteers by means of a portable data recording system. A number of pressure events and non-events were selected from 9 recordings and used for training the network. The performance of the trained network was then verified on recordings from the remaining 20 volunteers. The accuracy and sensitivity of the two systems were comparable. However, the neural network recognized pressure peaks clearly generated by muscular activity that had escaped detection by the conventional program. In conclusion, we believe that neu-rocomputing has potential advantages for automatic analysis of gastrointestinal motility data.

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