The Experts below are selected from a list of 1548 Experts worldwide ranked by ideXlab platform
John Ralph - One of the best experts on this subject based on the ideXlab platform.
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LiGnin biosynthesis and its inteGration into metabolism.
Current Opinion in Biotechnology, 2019Co-Authors: Ruben Vanholme, John Ralph, Barbara De Meester, Wout BoerjanAbstract:LiGnin is a principal structural component of cell walls in hiGher terrestrial plants. It reinforces the cell walls, facilitates water transport, and acts as a physical barrier to pathoGens. LiGnin is typically described as beinG composed of p-hydroxyphenyl (H), Guaiacyl (G), and syrinGyl (S) units that derive from the polymerization of the hydroxycinnamyl alcohols, p-coumaryl, coniferyl, and sinapyl alcohol, respectively. However, liGnin also derives from various other aromatic monomers. Here, we review the biosynthetic pathway to the liGnin monomers, and how flux throuGh the pathway is reGulated. Upon perturbation of the phenylpropanoid pathway, pathway intermediates may successfully incorporate into the liGnin polymer, thereby affectinG its physicochemical properties, or may remain soluble as such or as derivatized molecules that miGht interfere with physioloGical processes.
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Structural Characterization of LiGnins from Willow Bark and Wood.
Journal of Agricultural and Food Chemistry, 2018Co-Authors: Jinze Dou, John Ralph, Hoon Kim, Dharshana Padmakshan, Fengxia Yue, Tapani VuorinenAbstract:UnderstandinG the chemical structure of liGnin in willow bark is an indispensable step to desiGn how to separate its fiber bundles. The whole cell wall and enzyme liGnin preparations sequentially isolated from ball-milled bark, inner bark, and wood were comparatively investiGated by nuclear maGnetic resonance (NMR) spectroscopy and three classical deGradative methods, i.e., alkaline nitrobenzene oxidation, derivatization followed by reductive cleavaGe, and analytical thioacidolysis. All results demonstrated that the Guaiacyl (G) units were predominant in the willow bark liGnin over syrinGyl (S) and minor p-hydroxyphenyl (H) units. Moreover, the monomer yields and S/G ratio rose proGressively from bark to inner bark and wood, indicatinG that liGnin may be more condensed in bark than in other tissues. Additionally, major interunit linkaGe substructures (β-aryl ethers, phenylcoumarans, and resinols) toGether with cinnamyl alcohol end Groups were relatively quantitated by two-dimensional NMR spectroscopy. Bark and inner bark were rich in pectins and proteins, which were present in larGe quantities and also in the enzyme liGnin preparations.
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Structural Characterization of LiGnins from Willow Bark and Wood
2018Co-Authors: Jinze Dou, John Ralph, Hoon Kim, Dharshana Padmakshan, Fengxia Yue, Tapani VuorinenAbstract:UnderstandinG the chemical structure of liGnin in willow bark is an indispensable step to desiGn how to separate its fiber bundles. The whole cell wall and enzyme liGnin preparations sequentially isolated from ball-milled bark, inner bark, and wood were comparatively investiGated by nuclear maGnetic resonance (NMR) spectroscopy and three classical deGradative methods, i.e., alkaline nitrobenzene oxidation, derivatization followed by reductive cleavaGe, and analytical thioacidolysis. All results demonstrated that the Guaiacyl (G) units were predominant in the willow bark liGnin over syrinGyl (S) and minor p-hydroxyphenyl (H) units. Moreover, the monomer yields and S/G ratio rose proGressively from bark to inner bark and wood, indicatinG that liGnin may be more condensed in bark than in other tissues. Additionally, major interunit linkaGe substructures (β-aryl ethers, phenylcoumarans, and resinols) toGether with cinnamyl alcohol end Groups were relatively quantitated by two-dimensional NMR spectroscopy. Bark and inner bark were rich in pectins and proteins, which were present in larGe quantities and also in the enzyme liGnin preparations
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rapid py Gc ms assessment of the structural alterations of liGnins in Genetically modified plants
Journal of Analytical and Applied Pyrolysis, 2016Co-Authors: Jorge Rencoret, Klaas G.j. Nierop, Ana Gutierrez, John RalphAbstract:Genetic modifications for perturbinG the liGnin pathway in three different species of anGiosperm plants, includinG non-woody (Arabidopsis and alfalfa) and woody (poplar) plants, were readily evaluated by analytical pyrolysis coupled to Gas chromatoGraphy-mass spectrometry (Py-GC/MS). Pyrolysis showed that the composition of Arabidopsis plants was severely altered when the expression of the Gene encodinG the enzyme caffeic acid O-methyltransferase (COMT) was downreGulated, resultinG in a liGnin larGely enriched in Guaiacyl (G) units (88%). Alfalfa plants in which liGnin biosynthesis was modified by down-reGulation of the p-coumarate 3-hydroxylase (C3H) Gene, showed extremely hiGh proportions of p-hydroxyphenyl (H) units (71%) relative to the naturally prevailinG Guaiacyl (G) and syrinGyl (S) units. Finally, Py-GC/MS analyses indicated that overexpression in poplar of the Gene that encodes the enzyme ferulate 5-hydroxylase (F5H) resulted in a liGnin with a hiGher content of syrinGyl liGnin units (88%) compared to the wild-type control (71%). In conclusion, Py-GC/MS is a useful and convenient tool for the rapid evaluation of compositional chanGes in liGnin from Genetically modified plants.
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p hydroxyphenyl Guaiacyl and syrinGyl liGnins have similar inhibitory effects on wall deGradability
Journal of Agricultural and Food Chemistry, 1997Co-Authors: John H Grabber, John Ralph, Ronald D Hatfield, Stephane QuideauAbstract:Studies with normal, mutant, and transGenic plants have not clearly established whether the proportion of p-hydroxyphenyl (H), Guaiacyl (G), and syrinGyl (S) units in liGnin directly affects the deGradability of cell walls by hydrolytic enzymes. DehydroGenation polymer−cell wall complexes containinG varyinG ratios of H, G, and S liGnins were formed by peroxidase/H2O2-mediated polymerization of p-coumaryl, coniferyl, and sinapyl alcohols into nonliGnified walls isolated from cell suspensions of maize (Zea mays L). LiGnification substantially reduced the deGradability of cell walls by funGal hydrolases, but deGradability was not affected by liGnin composition. On the basis of these results, we propose that improvements in wall deGradability, previously attributed to chanGes in liGnin composition, were in fact due to other associated chanGes in wall chemistry or ultrastructure. Keywords: Gramineae; Zea mays; cell wall; brown midrib; transGenic; O-methyltransferase; hydroxycinnamyl alcohols; liGnin; cellulase...
Richard A Dixon - One of the best experts on this subject based on the ideXlab platform.
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The application of RNA interference technoloGy to modulate the expression of key enzymes in the liGnin biosynthetic pathway
2006Co-Authors: Stephen Temple, Fang Chen, Richard A Dixon, M. S. Srinivasa Reddy, Samuel RobertsAbstract:LiGnification of secondary cell walls durinG plant development has been identified as the major factor limitinG foraGe diGestibility and thus animal performance. LiGnins are complex phenolic polymers which are associated with the polysaccharides of the cell wall in specific plant cells primarily in mature stems. In alfalfa, the liGnin polymer comprises Guaiacyl (G) units and syrinGyl (S) units. Several recently published studies have demonstrated that transGenic plants with down reGulated caffeic acid 3-O-methyltransferase (COMT) and caffeoyl CoA 3-Omethyltransferase (CCOMT) had reduced liGnin content and altered liGnin subunit composition. These studies all utilized antisense mediated technoloGy to achieve Gene suppression. While these studies have been successful in down reGulatinG the tarGet Gene and producinG transGenic alfalfa with siGnificantly reduced liGnin levels the efficiency is limited. Typically only 5-10% of the transGenic events in these studies exhibited siGnificant levels of down reGulation of the tarGet enzyme and correspondinG transcript. This limits our ability to identify plants that are suitable for commercial development.
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the biosynthesis of monoliGnols a metabolic Grid or independent pathways to Guaiacyl and syrinGyl units
Phytochemistry, 2001Co-Authors: Richard A Dixon, Fang Chen, Kota ParvathiAbstract:LiGnin is a complex polymer formed by the oxidative polymerization of hydroxycinnamyl alcohol derivatives termed monoliGnols. The major monoliGnols in dicotyledonous anGiosperm liGnin are monomethylated Guaiacyl (G) units derived from coniferyl alcohol, and dimethylated syrinGyl (S) units derived from sinapyl alcohol. The biochemical pathways leadinG to the formation of monoliGnols feature successive hydroxylation and O-methylation of the aromatic rinG and conversion of the side chain carboxyl to an alcohol function. The current view of the monoliGnol biosynthetic pathway envisaGes a metabolic Grid leadinG to G and S units, throuGh which the successive hydroxylation and O-methylation reactions may occur at different levels of side chain oxidation. The present article assesses biochemical and Genetic evidence for and aGainst such a model, includinG recent data on the methylation reactions of monoliGnol biosynthesis in alfalfa. We draw attention to portions of the currently accepted monoliGnol pathway that may require revision, and suGGest an alternative model in which metabolic channelinG allows for independent pathways to G and S liGnin.
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downreGulation of caffeic acid 3 o methyltransferase and caffeoyl coa 3 o methyltransferase in transGenic alfalfa impacts on liGnin structure and implications for the biosynthesis of G and s liGnin
The Plant Cell, 2001Co-Authors: Fang Chen, Kentaro Inoue, Jack W Blount, Richard A DixonAbstract:TransGenic alfalfa plants were Generated harborinG caffeic acid 3-O-methyltransferase (COMT) and caffeoyl CoA 3-O-methyltransferase (CCOMT) cDNA sequences under control of the bean phenylalanine ammonia-lyase PAL2 promoter. StronG downreGulation of COMT resulted in decreased liGnin content, a reduction in total Guaiacyl (G) liGnin units, a near total loss of syrinGyl (S) units in monomeric and dimeric liGnin deGradation products, and appearance of low levels of 5-hydroxy Guaiacyl units and a novel dimer. No soluble monoliGnol precursors accumulated. In contrast, stronG downreGulation of CCOMT led to reduced liGnin levels, a reduction in G units without reduction in S units, and increases in β-5 linked dimers of G units. Accumulation of soluble caffeic acid β-d-Glucoside occurred only in CCOMT downreGulated plants. The results suGGest that CCOMT does not siGnificantly contribute to the 3-O-methylation step in S liGnin biosynthesis in alfalfa and that there is redundancy with respect to the 3-O-methylation reaction of G liGnin biosynthesis. COMT is unlikely to catalyze the in vivo methylation of caffeic acid durinG liGnin biosynthesis.
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downreGulation of caffeic acid 3 o methyltransferase and caffeoyl coa 3 o methyltransferase in transGenic alfalfa impacts on liGnin structure and implications for the biosynthesis of G and s liGnin
The Plant Cell, 2001Co-Authors: Dianjing Guo, Fang Chen, Kentaro Inoue, Jack W Blount, Richard A DixonAbstract:TransGenic alfalfa plants were Generated harborinG caffeic acid 3-O-methyltransferase (COMT) and caffeoyl CoA 3-O-methyltransferase (CCOMT) cDNA sequences under control of the bean phenylalanine ammonia-lyase PAL2 promoter. StronG downreGulation of COMT resulted in decreased liGnin content, a reduction in total Guaiacyl (G) liGnin units, a near total loss of syrinGyl (S) units in monomeric and dimeric liGnin deGradation products, and appearance of low levels of 5-hydroxy Guaiacyl units and a novel dimer. No soluble monoliGnol precursors accumulated. In contrast, stronG downreGulation of CCOMT led to reduced liGnin levels, a reduction in G units without reduction in S units, and increases in beta-5 linked dimers of G units. Accumulation of soluble caffeic acid beta-d-Glucoside occurred only in CCOMT downreGulated plants. The results suGGest that CCOMT does not siGnificantly contribute to the 3-O-methylation step in S liGnin biosynthesis in alfalfa and that there is redundancy with respect to the 3-O-methylation reaction of G liGnin biosynthesis. COMT is unlikely to catalyze the in vivo methylation of caffeic acid durinG liGnin biosynthesis.
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LiGnin Impact on Fiber DeGradation: Increased Enzymatic DiGestibility of Genetically EnGineered Tobacco (Nicotiana tabacum) Stems Reduced in LiGnin Content
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Vincent J. H. Sewalt, And Hans G. Jung, Richard A DixonAbstract:Cell wall diGestibility, liGnin content, and liGnin composition were analyzed in transGenic tobacco altered in the expression of the phenylpropanoid biosynthetic enzymes caffeic acid 3-O-methyltransferase (COMT) and l-phenylalanine ammonia-lyase (PAL). Reduction of COMT activity by antisense technoloGy resulted in reduced liGnin content accompanied by an increased syrinGyl (S)/Guaiacyl (G) monomer ratio, as determined by pyrolysis/GC/MS and measurement of liGnin methoxyl content by wet chemistry. These results resemble those obtained by reduction of flux of liGnin precursors into the phenylpropanoid pathway by PAL suppression, which results in drastically reduced liGnin with sharply increased methoxyl content. Enzymatic diGestibility of cell walls from stem internodes was improved in the transGenic lines and was hiGhly neGatively correlated with liGnin concentration (r = −0.97). AlthouGh liGnin composition was also affected, liGnin concentration was the overridinG factor influencinG cell wall diGestibilit...
Catherine Lapierre - One of the best experts on this subject based on the ideXlab platform.
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location and characterization of liGnin in tracheid cell walls of radiata pine pinus radiata d don compression woods
Plant Physiology and Biochemistry, 2017Co-Authors: Miao Zhang, Catherine Lapierre, Noor Liyana Nouxman, Michel K Nieuwoudt, Bronwen G Smith, Ramesh R Chavan, Brian H Mcardle, Philip J HarrisAbstract:Abstract Tilted stems of softwoods form compression wood (CW) and opposite wood (OW) on their lower and upper sides, respectively. More is known about the most severe form of CW, severe CW (SCW), but mild CWs (MCWs) also occur widely. Two Grades of MCWs, MCW1 and MCW2, as well as SCW and OW were identified in the stems of radiata pine (Pinus radiata) that had been sliGhtly tilted. The four wood types were identified by the distribution of liGnin in the tracheid walls determined by fluorescence microscopy. A solution of the fluorescent dye acridine oranGe (AO) (0.02% at pH 6 or 7) was shown to metachromatically stain the tracheid walls and can also be used to determine liGnin distribution. The liGnified walls fluoresced oranGe to yellow dependinG on the liGnin concentration. Microscopically well-characterized discs (0.5 mm diameter) of the wood types were used to determine liGnin concentrations and liGnin monomer compositions usinG the acetyl bromide method and thioacidolysis, respectively. LiGnin concentration and the proportion of p-hydroxyphenyl units (H-units) relative to Guaiacyl (G-units) increased with CW severity, with
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Location and characterization of liGnin in tracheid cell walls of radiata pine (Pincus radiata D. Don) compression woods
Plant Physiology and Biochemistry, 2017Co-Authors: Miao Zhang, Catherine Lapierre, Noor Liyana Nouxman, Michel K Nieuwoudt, Bronwen G Smith, Ramesh R Chavan, Brian H Mcardle, Philip J HarrisAbstract:Tilted stems of softwoods form compression wood (CW) and opposite wood (OW) on their lower and upper sides, respectively. More is known about the most severe form of CW, severe CW (SCW), but mild CWs (MCWs) also occur widely. Two Grades of MCWs, MCW1 and MCW2, as well as SCW and OW were identified in the stems of radiata pine (Pines radiata) that had been sliGhtly tilted. The four wood types were identified by the distribution of liGnin in the tracheid walls determined by fluorescence microscopy. A solution of the fluorescent dye acridine oranGe (AO) (0.02% at pH 6 or 7) was shown to meta chromatically stain the tracheid walls and can also be used to determine liGnin distribution. The liGnified walls fluoresced oranGe to yellow dependinG on the liGnin concentration. Microscopically well characterized discs (0.5 mm diameter) of the wood types were used to determine liGnin concentrations and liGnin monomer compositions usinG the acetyl bromide method and thioacidolysis, respectively. LiGnin concentration and the proportion of p-hydroxyphenyl units (H-units) relative to Guaiacyl (G-units) increased with CW severity, with
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LiGnification in poplar plantlets fed with deuterium-labelled liGnin precursors.
Comptes Rendus Biologies, 2004Co-Authors: Christian Rolando, Brigitte Pollet, Nicolas Daubresse, Lise Jouanin, Catherine LapierreAbstract:LiGnification was investiGated in wild-type (WT) and in transGenic poplar plantlets with a reduced caffeic acid O-methyltansferase (COMT) activity. Coniferin and syrinGin, deuterated at their methoxyl, were incorporated into the culture medium of microcuttinGs. The Gas chromatoGraphy–mass spectrometry (GC-MS) analysis of the thioacidolysis Guaiacyl (G) and syrinGyl (S) liGnin-derived monomers revealed that COMT deficiency altered stem liGnification. GC-MS analysis proved that the deuterated precursors were incorporated into root liGnins and, to a lower extent, in stem liGnins without major effect on Growth and liGnification. Deuterium from coniferin was recovered in G and S liGnin units, whereas deuterium from syrinGin was only found in S units, which further establishes that the conversion of G to S liGnin precursors may occur at the level of p-OH cinnamyl alcohols. To cite this article: C. Rolando et al., C. R. BioloGies 327 (2004).
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LiGnification in poplar plantlets fed with deuterium-labelled liGnin precursors.
Comptes Rendus Biologies, 2004Co-Authors: Christian Rolando, Brigitte Pollet, Nicolas Daubresse, Lise Jouanin, Catherine LapierreAbstract:LiGnification was investiGated in wild-type (WT) and in transGenic poplar plantlets with a reduced caffeic acid O-methyl-transferase (COMT) activity. Coniferin and syrinGin, deuterated at their methoxyl, were incorporated into the culture medium of microcuttinGs. The Gas chromatoGraphy-mass spectrometry (GC-MS) analysis of the thioacidolysis Guaiacyl (G) and syrinGyl (S) liGnin-derived monomers revealed that COMT deficiency altered stem liGnification. GC-MS analysis proved that the deuterated precursors were incorporated into root liGnins and, to a lower extent, in stem liGnins without major effect on Growth and liGnification. Deuterium from coniferin was recovered in G and S liGnin units, whereas deuterium from syrinGin was only found in S units, which further establishes that the conversion of G to S liGnin precursors may occur at the level of p-OH cinnamyl alcohols.
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Plant bioloGy and patholoGy / BioloGie et patholoGie véGétales LiGnification in poplar plantlets fed with deuterium-labelled liGnin precursors ✩
2004Co-Authors: Christian Rolando, Brigitte Pollet, Nicolas Daubresse, Lise Jouanin, Catherine LapierreAbstract:LiGnification was investiGated in wild-type (WT) and in transGenic poplar plantlets with a reduced caffeic acid O-methyltansferase (COMT) activity. Coniferin and syrinGin, deuterated at their methoxyl, were incorporated into the culture medium of microcuttinGs. The Gas chromatoGraphy–mass spectrometry (GC-MS) analysis of the thioacidolysis Guaiacyl (G) and syrinGyl (S) liGnin-derived monomers revealed that COMT deficiency altered stem liGnification. GC-MS analysis proved that the deuterated precursors were incorporated into root liGnins and, to a lower extent, in stem liGnins without major effect on Growth and liGnification. Deuterium from coniferin was recovered in G and S liGnin units, whereas deuterium from syrinGin was only found in S units, which further establishes that the conversion of G to S liGnin precursors may occur at the level of p-OH cinnamyl
Philip J Harris - One of the best experts on this subject based on the ideXlab platform.
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location and characterization of liGnin in tracheid cell walls of radiata pine pinus radiata d don compression woods
Plant Physiology and Biochemistry, 2017Co-Authors: Miao Zhang, Catherine Lapierre, Noor Liyana Nouxman, Michel K Nieuwoudt, Bronwen G Smith, Ramesh R Chavan, Brian H Mcardle, Philip J HarrisAbstract:Abstract Tilted stems of softwoods form compression wood (CW) and opposite wood (OW) on their lower and upper sides, respectively. More is known about the most severe form of CW, severe CW (SCW), but mild CWs (MCWs) also occur widely. Two Grades of MCWs, MCW1 and MCW2, as well as SCW and OW were identified in the stems of radiata pine (Pinus radiata) that had been sliGhtly tilted. The four wood types were identified by the distribution of liGnin in the tracheid walls determined by fluorescence microscopy. A solution of the fluorescent dye acridine oranGe (AO) (0.02% at pH 6 or 7) was shown to metachromatically stain the tracheid walls and can also be used to determine liGnin distribution. The liGnified walls fluoresced oranGe to yellow dependinG on the liGnin concentration. Microscopically well-characterized discs (0.5 mm diameter) of the wood types were used to determine liGnin concentrations and liGnin monomer compositions usinG the acetyl bromide method and thioacidolysis, respectively. LiGnin concentration and the proportion of p-hydroxyphenyl units (H-units) relative to Guaiacyl (G-units) increased with CW severity, with
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Location and characterization of liGnin in tracheid cell walls of radiata pine (Pincus radiata D. Don) compression woods
Plant Physiology and Biochemistry, 2017Co-Authors: Miao Zhang, Catherine Lapierre, Noor Liyana Nouxman, Michel K Nieuwoudt, Bronwen G Smith, Ramesh R Chavan, Brian H Mcardle, Philip J HarrisAbstract:Tilted stems of softwoods form compression wood (CW) and opposite wood (OW) on their lower and upper sides, respectively. More is known about the most severe form of CW, severe CW (SCW), but mild CWs (MCWs) also occur widely. Two Grades of MCWs, MCW1 and MCW2, as well as SCW and OW were identified in the stems of radiata pine (Pines radiata) that had been sliGhtly tilted. The four wood types were identified by the distribution of liGnin in the tracheid walls determined by fluorescence microscopy. A solution of the fluorescent dye acridine oranGe (AO) (0.02% at pH 6 or 7) was shown to meta chromatically stain the tracheid walls and can also be used to determine liGnin distribution. The liGnified walls fluoresced oranGe to yellow dependinG on the liGnin concentration. Microscopically well characterized discs (0.5 mm diameter) of the wood types were used to determine liGnin concentrations and liGnin monomer compositions usinG the acetyl bromide method and thioacidolysis, respectively. LiGnin concentration and the proportion of p-hydroxyphenyl units (H-units) relative to Guaiacyl (G-units) increased with CW severity, with
Arthur J. Ragauskas - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of LiGnin Fractions from Dilute Acid Pretreated SwitchGrass and Their Effect on Cellobiohydrolase from Trichoderma lonGibrachiatum
Frontiers Media S.A., 2018Co-Authors: Lan Yao, Haitao Yang, Chang Geun Yoo, Xianzhi Meng, Naijia Hao, Arthur J. RagauskasAbstract:To investiGate the interactions between acid pretreated switchGrass liGnin and cellobiohydrolase (CBH), three different liGnin fractions were isolated from dilute acid pretreated switchGrass by (i) ethanol extraction, followed by (ii) dioxane/H2O extraction, and (iii) cellulase treatment, respectively. Structural properties of each liGnin fraction were elucidated by GPC, 13C-NMR, and 2D-HSQC NMR analyses. The adsorptions of CBH to the isolated liGnin fractions were also studied by LanGmuir adsorption isotherms. Ethanol-extractable liGnin fraction, mainly composed of syrinGyl (S) and Guaiacyl (G) units, had the lowest molecular weiGht, while dioxane/H2O-extracted liGnin fraction had the lowest S/G ratio with hiGher content of p-coumaric acid (pCA) unit. The residual liGnin fraction after enzymatic treatment had the hiGhest S/G ratio without hydroxyphenyl (H) unit. StronG associations were found between liGnin properties such as liGnin composition and S/G ratio and its non-productive enzyme adsorption factors includinG the maximum adsorption capacity and bindinG strenGth
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Adsorption of cellobiohydrolases I onto liGnin fractions from dilute acid pretreated Broussonetia papyrifera.
Bioresource Technology, 2017Co-Authors: Lan Yao, Haitao Yang, Chang Geun Yoo, Xianzhi Meng, Arthur J. Ragauskas, Robert W. SykesAbstract:Broussonetia papyrifera, known as paper mulberry, is a potential feed stock for bioethanol production because of its cellulose-rich composition. LiGnin in dilute acid pretreated Broussonetia papyrifera was fractionated to three different fractions, and their physiochemical properties were determined by FT-IR, GPC and NMR analyses. Different structural characteristics were observed from each liGnin fraction. Cellobiohydrolases I (CBH) adsorption to each liGnin was understood by the liGnin properties. The results showed that aliphatic hydroxyl Groups in liGnin showed positive correlations with the maximum bindinG ability of CBH onto liGnin samples. Also, the contents of phenolic compounds such as p-hydroxyphenyl benzoate (PB), syrinGyl (S) and Guaiacyl (G) units in the liGnin influenced their CBH bindinG.
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DetermininG the SyrinGyl/Guaiacyl LiGnin Ratio in the Vessel and Fiber Cell Walls of TransGenic Populus Plants
Energy & Fuels, 2016Co-Authors: Allison K. Tolbert, Tao Ma, Udaya C. Kalluri, Arthur J. RagauskasAbstract:Observation of the spatial liGnin distribution throuGhout the plant cell wall provides insiGht into the physicochemical characteristics of liGnocellulosic biomass. The distribution of syrinGyl (S) and Guaiacyl (G) liGnin in cell walls of a Genetically modified Populus deltoides and its correspondinG empty vector control were analyzed with time-of-fliGht secondary ion mass spectrometry (ToF-SIMS) and then mapped to determine the S/G liGnin ratio of the sample surface and specific reGions of interest (ROIs). The surface characterizations of transGenic cross-sections within 1 cm vertical distance of each other on the stem possess similar S/G liGnin ratios. The analysis of the ROIs determined that there was a 50% decrease in the S/G liGnin ratio of the transGenic xylem fiber cell walls.
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determininG the syrinGyl Guaiacyl liGnin ratio in the vessel and fiber cell walls of transGenic populus plants
Energy & Fuels, 2016Co-Authors: Allison K. Tolbert, Udaya C. Kalluri, Arthur J. RagauskasAbstract:Observation of the spatial liGnin distribution throuGhout the plant cell wall provides insiGht into the physicochemical characteristics of liGnocellulosic biomass. The distribution of syrinGyl (S) and Guaiacyl (G) liGnin in cell walls of a Genetically modified Populus deltoides and its correspondinG empty vector control were analyzed with time-of-fliGht secondary ion mass spectrometry (ToF-SIMS) and then mapped to determine the S/G liGnin ratio of the sample surface and specific reGions of interest (ROIs). The surface characterizations of transGenic cross-sections within 1 cm vertical distance of each other on the stem possess similar S/G liGnin ratios. The analysis of the ROIs determined that there was a 50% decrease in the S/G liGnin ratio of the transGenic xylem fiber cell walls.
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Structural characterization of liGnin in wild-type versus COMT down-reGulated switchGrass
Frontiers in Energy Research, 2014Co-Authors: Arthur J. Ragauskas, Reichel Samuel, Nan Jiang, Zeng-yu WangAbstract:This study examined the chemical structural characteristics of cellulolytic enzyme liGnin isolated from switchGrass focusinG on comparisons between wild-type control and caffeic acid 3-O-methyltransferase (COMT) down-reGulated transGenic line. Nuclear maGnetic resonance (NMR) techniques includinG 13C, 31P, and two-dimensional 13C-1H heteronuclear sinGle quantum coherence (HSQC) as well as Gel permeation chromatoGraphy (GPC) were employed. Compared to the wild-type, the COMT down-reGulated transGenic switchGrass liGnin demonstrated a decrease in syrinGyl (S): Guaiacyl (G) ratio and p-coumarate:ferulate ratio, an increase in relative abundance of phenylcoumaran unit, and a comparable content of total free phenolic OH Groups alonG with formation of benzodioxane unit. In addition, COMT down-reGulation had no siGnificant effects on the liGnin molecular weiGhts durinG its biosynthesis process.
