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PubMed1984

Purification and properties of cinnamoyl-CoA reductase and cinnamyl alcohol dehydrogenase from poplar stems (Populus X euramericana).

Cinnamoyl-CoA reductase and cinnamyl alcohol dehydrogenase were purified to apparent homogeneity from poplar stems (Populus euramericana) and their main properties were studied. Only one form was identified for each enzyme. The reductase corresponded to one polypeptide of molecular weight 36 000 and the cinnamyl alcohol dehydrogenase was constituted of two identical subunits of molecular weight 40 000. These characteristics are in agreement with most of the data obtained for the same enzymes isolated from other plants. The two reductive enzymes are inhibited by thiol reagents and a metal chelator 1,10-phenanthroline. The isoelectric point of the reductase (pH 7.5) and of the dehydrogenase (pH 5.6) were determined by chromatofocusing. The cinnamoyl-CoA reductase exhibit a decreasing affinity towards feruloyl-CoA, sinapoyl-CoA and p-coumaroyl-CoA. The cinnamyl alcohol dehydrogenase, which catalyses the reduction of the three cinnamaldehydes, exhibits its highest efficiency towards coniferaldehyde. In spite of differences in the monomeric composition of lignins from xylem and sclerenchyma the reductive enzymes isolated from these two lignified tissues exhibit the same substrate specificity. Consequently, they do not play an important role in the qualitative control of lignins in poplar tissues.

Alcohol Oxidoreductases↗
PubMed2007

Structural motifs of syringyl peroxidases predate not only the gymnosperm-angiosperm divergence but also the radiation of tracheophytes.

* The most distinctive variation in the monomer composition of lignins in vascular land plants is that found between the two main groups of seed plants. Thus, while gymnosperm lignins are typically composed of guaiacyl (G) units, angiosperm lignins are largely composed of similar levels of G and syringyl (S) units. * However, and contrary to what might be expected, peroxidases isolated from basal (Cycadales and Ginkgoales) and differentially evolved (Coniferales and Gnetales) gymnosperms are also able to oxidize S moieties, and this ability is independent of the presence or absence of S-type units in their lignins. * The results obtained led us to look at the protein database to search for homologies between gymnosperm peroxidases and true eudicot S-peroxidases, such as the Zinnia elegans peroxidase. * The findings showed that certain structural motifs characteristic of eudicot S-peroxidases (certain amino acid sequences and beta-sheet secondary structures) predate the gymnosperm-angiosperm divergence and the radiation of tracheophytes, since they are found not only in peroxidases from basal gymnosperms, ferns and lycopods, but also in peroxidases from the moss Physcomitrella patens (Bryopsida) and the liverwort Marchantia polymorpha (Marchantiopsida), which, as typical of bryophytes, do not have xylem tissue nor lignins.

Amino Acid Motifs↗
PubMed1977

Dietary fiber components: relationship to the rate and extent of ruminal digestion.

A mathematical model can serve as a useful reference for describing the mechanisms involved in digestion and for discussing the factors that influence the rate and extent of ruminal digestion. Ruminal digestion can be divided into four components: digestion rate, digestion lag, potential extent of digestion, and passage rate. Each component affects the apparent extent of digestion in a distinct manner and is influenced by separate factors. Digestion rate is directly related to apparent extent of digestion. It is not influenced by chemical entities presently being measured, but may be related to the morphological, crystalline, or physical nature of fiber. It may also be influenced by factors that inhibit or stimulate ruman microbial growth and their fiber-degrading enzymes. Digestion lag is inversely related to apparent extent of digestion; however, factors influencing it are poorly defined. The may include factors affecting microbial populations and their attachment to fiber prior to digestion; or the digestion lag may be related to the chemical or physical alteration of fiber that must occur before digestion can begin. The potential extent of digestion is directly related to apparent extent of digestion and is influenced by plant fiber composition, primarily. Lignin, and possibly silica, functions to limit the potential extent of digestion. Rate of passage essentially competes with rate of digestion for fiber particles as they pass through the rumen; therefore it is inversely related to the apparent extent of digestion. Passage rate is associated with feed intake level and particle size, although other factors such as type of diet and animal physiology may be important.

Animals↗
PubMedDate not supplied

Effects of sodium sulfite on recovery and composition of detergent fiber and lignin.

Use of sodium sulfite to reduce nitrogenous contamination in fiber analysis was evaluated. The effects of sodium sulfite on analytical accuracy and precision were examined for amylase-treated neutral detergent fiber (aNDF), sequentially determined acid detergent fiber (sADF), and acid detergent lignin (sADL) in animal feeds. In one experiment, 0.5 g sodium sulfite was added per sample during neutral detergent (ND) extraction. The treatment consistently reduced aNDF, sADF, and sADL values of 180 alfalfa samples and improved precision (decreased within-sample variance of replicated analyses). The greatest effect was on precision of sADL analysis, with within-sample variance reduced by more than 50%. In a second experiment, 24 animal feeds were analyzed for a aNDF, sADF, and sADL with and without addition of 0.5 g sodium sulfite per sample during ND extraction. Nitrogen contents of the recovered fiber fractions were determined. Sodium sulfite reduced fiber and lignin values and decreased nitrogen concentration in residues. Within-sample variance was lower in all analyses. In a third experiment, 23 animal feeds were analyzed for aNDF with sodium sulfite at 0, 0.25, 0.5, and 1.0 g per sample. Average aNDF of feeds was reduced by each additional increment of sodium sulfite; however, 1.0 g sodium sulfite resulted in only a slight reduction in aNDF compared with 0.5 g. Therefore, 0.5 g sodium sulfite per sample should be added to samples prior to aNDF analysis.

Amylases↗
PubMed2006

NMR characterization of lignins isolated from fruit and vegetable insoluble dietary fiber.

Compositional information for lignins in food is rare and concentrated on cereal grains and brans. As lignins are suspected to have important health roles in the dietary fiber complex, the confusing current information derived from nonspecific lignin determination methods needs to be augmented by diagnostic structural studies. For this study, lignin fractions were isolated from kiwi, pear, rhubarb, and, for comparison, wheat bran insoluble dietary fiber. Clean pear and kiwi lignin isolates allowed for substantive structural profiling, but it is suggested that the significance of lignin in wheat has been overestimated by reliance on nonspecific analytical methods. Volume integration of NMR contours in two-dimensional (13)C-(1)H correlation spectra shows that pear and wheat lignins have comparable guaiacyl and syringyl contributions and that kiwi lignins are particularly guaiacyl-rich (approximately 94% guaiacyl) and suggest that rhubarb lignins, which could not be isolated from contaminating materials, are as syringyl-rich (approximately 96% syringyl) as lignins from any known natural or transgenic fiber source. Typical lignin structures, including those newly NMR-validated (glycerols, spirodienones, and dibenzodioxocins), and resinols implicated as possible mammalian lignan precursors in the gut are demonstrated via their NMR correlation spectra in the fruit and vegetable samples. A novel putative benzodioxane structure appears to be associated with the kiwi lignin. It is concluded that the fruits and vegetables examined contain authentic lignins and that the detailed structural analysis exposes limitations of currently accepted analytical methods.

Dietary Fiber↗
PubMed2003

Mechanical, chemical and X-ray analysis of wood in the two tropical lianas Bauhinia guianensis and Condylocarpon guianense: variations during ontogeny.

Mechanical and chemical properties as well as microfibril angles of wood tissues from different ontogenetic stages are determined for the neotropical lianas Bauhinia guianensis and Condylocarpon guianense. The mechanical properties include the elastic moduli under bending and under dynamic torsion. The chemical analyses cover (i) the content of cellulose, lignin and hemicelluloses fractions, (ii) the monomeric composition of the uncondensed lignin, and (iii) the composition of the hemicelluloses with respect to neutral monosaccharides. By comparing the wood properties of these lianas with the corresponding properties of wood from self-supporting deciduous trees, common characteristics and differences are revealed. Additionally, the changes in the lignin and polysaccharides fractions as well as the variations in microfibril orientation that occur during ontogeny of the two liana species are discussed with regard to their implications for the mechanical properties of wood.

Apocynaceae↗
PubMed2004

Coordinated genetic regulation of growth and lignin revealed by quantitative trait locus analysis of cDNA microarray data in an interspecific backcross of eucalyptus.

Phenotypic, genotypic, and transcript level (microarray) data from an interspecific backcross population of Eucalyptus grandis and Eucalyptus globulus were integrated to dissect the genetic and metabolic network underlying growth variation. Transcript abundance, measured for 2,608 genes in the differentiating xylem of a 91 (E. grandis x E. globulus) x E. grandis backcross progeny was correlated with diameter variation, revealing coordinated down-regulation of genes encoding enzymes of the lignin biosynthesis and associated methylation pathways in fast growing individuals. Lignin analysis of wood samples confirmed the content and quality predicted by the transcript levels measured on the microarrays. Quantitative trait locus (QTL) analysis of transcript levels of lignin-related genes showed that their mRNA abundance is regulated by two genetic loci, demonstrating coordinated genetic control over lignin biosynthesis. These two loci colocalize with QTLs for growth, suggesting that the same genomic regions are regulating growth, and lignin content and composition in the progeny. Genetic mapping of the lignin genes revealed that most of the key biosynthetic genes do not colocalize with growth and transcript level QTLs, with the exception of the locus encoding the enzyme S-adenosylmethionine synthase. This study illustrates the power of integrating quantitative analysis of gene expression data and genetic map information to discover genetic and metabolic networks regulating complex biological traits. (Sequence data for this article have been deposited with the EMBL/GenBank data libraries under accession numbers CB 967505 to CB 968059; CD 667988 to CD 670002; CD 670004; CD 670097; CD 670101 to CD 670112; and CD 670114 to CD 670137.)

Base Sequence↗
PubMed2003

Synthesis and characterization of dehydrogenation polymers in Gluconacetobacter xylinus cellulose and cellulose/pectin composite.

To mimic the lignin polymerization process, mats of bacterial cellulose and of a pectin/cellulose composite were used as a host matrix for in vitro polymerization of coniferyl alcohol. A diffusion cell was used to allow the diffusion of both hydrogen peroxide and coniferyl alcohol into the peroxidase impregnated cellulose mats through dialysis membranes. The results indicate that significant polymerization occurs within the mats. The resulting binary and ternary blends were imaged by scanning electron microscopy (SEM) and characterized by chemical means. The presence of pectin induces a better dispersion of the synthetic lignin in the cellulose network and enhances the proportion of alkyl-aryl-ether in the polymer.

Cellulose↗
PubMed2004

[Advances in research on lignin biosynthesis and its genetic engineering].

Lignin, one of the main components in vascular plants, is important for the adaptation of terrestrial plants to environment during evolution. However, its presence in plants has negative effects on wood processing during pulping and stock breeding. Therefore much attention has been focused on the regulation of lignin biosynthesis. The pathways leading to the synthesis of lignin polymers have been studied for decades. Much understanding of lignin biosynthesis has been advanced. This paper reviewed the recent progress made in the various steps associated with monolignol biosynthesis. It includes the catalysis by three enzymes, i.e. p-coumarate-3-hydroxylase (C3H), ferulate-5-hydroxylase (F5H) and caffeic acid 3-O-methyltransferase (COMT); the multiform biosynthetic pathway of syringyl (S) lignin in angiosperms; the biosynthesis route of guaiacyl (G) and syringyl (S) lignin specifically regulated by cinnamyl alcohol dehydrogenase (CAD) and sinapyl alcohol dehydrogenase (SAD) and the formation of the lignin macromolecule. Based on the elucidation of lignin biosynthesis pathway, it has also been given the achievements in lignin gene engineering. Many studies were concentrated on the modification of lignin content and composition. In some cases, the potential value of transgenic plants with modified lignin beneficial for pulping has been demonstrated. To better understand the mechanism of lignin biosynthesis and improve the properties of plants, new biotechnological strategies can be developed, which include combinatorial modification of multiple lignin traits in plants through multigene cotransformation, transcriptional control of lignin biosynthesis and the application of RNA interference. The identification of novel genes by molecular and genetic approaches will be useful in opening up new avenues of lignin modification in the future.

Genetic Engineering↗
PubMed2001

Repression of O-methyltransferase genes in transgenic tobacco affects lignin synthesis and plant growth.

Among the different enzymatic steps leading to lignin biosynthesis, two methylation reactions introduce the methyl groups borne by guaiacyl (G) and syringyl (S) units. Tobacco possesses a complex system of methylation comprising three classes of CCoAOMTs (caffeoyl-CoA-O-methyltransferases) and two classes of COMTs (caffeic acid OMTs). Antisense plants transformed with the CCoAOMT sequence alone or fused to COMT I sequence have been produced and compared to ASCOMT I plants in order to study the specific role of each OMT isoform in lignin biosynthesis, plant development and resistance to pathogens. Tobacco plants strongly inhibited in OMT activities have been selected and analyzed. Whereas antisense COMT I plants exhibited no visual phenotype, CCoAOMT repression was shown to strongly affect the development of both single and double transformants: a reduction of plant growth and the alteration of flower development were observed in the most inhibited plants. Lignin analysis performed by Klason and thioacidolysis methods, showed a decrease in the lignin quantity and changes in the lignin structure of ASCCoAOMT and ASCCoAOMT/ASCOMT I transgenics but not in ASCOMT I plants. Inhibition of COMT I in single as well as in double transformed tobacco was demonstrated to decrease S unit synthesis and to provoke the accumulation of 5-hydroxyguaiacyl lignin units. ASCCoAOMT/ASCOMT I tobacco was affected in lignin amount and composition, thus demonstrating additive effects of inhibition of both enzymes. The changes of lignin profiles and the phenotypical and molecular alterations observed in the different transgenic lines were particularly prominent at the later stages of plant development.

Lignin↗
PubMed1999

A method of fast separation of lignin peroxidases using convective interaction media disks.

The HPLC separation of lignin peroxidase isoenzymes using Convective Interaction Media disks containing quaternary amine and diethylaminoethyl ion-exchange active groups is proposed. In contrast to standard HPLC procedures the separation can be performed within a few minutes without considerably affecting the separation resolution. The method is reproducible and gives a linear response of integrated peak area to protein concentration for all measured isoenzymes. The separation resolution is retained unchanged by applying crude culture filtrate instead of a sample previously frozen and dialyzed. The optimized method might therefore be used for on-line monitoring of lignin peroxidase isoenzyme composition during fermentation. On the other hand, the proposed method is comparable in time to the original method of lignin peroxidase activity measurement (proposed by Tien and Kirk), providing additionally the isoenzyme composition.

Chromatography, High Pressure Liquid↗
PubMed1992

Effect of alkaline hydrogen peroxide treatment on cell wall composition and digestion kinetics of sugarcane residues and wheat straw.

Our objective was to characterize changes in cell wall composition and digestibility of sugarcane bagasse, pith from bagasse, and wheat straw after treatment with alkaline hydrogen peroxide (AHP). The AHP treatment solution contained 1% H2O2 (wt/vol) maintained at pH 11.5 with NaOH. The H2O2 in solution amounted to 25% of the quantity of substrate treated. After treatment, residues were washed and dried. Detergent fiber composition, total fiber components (neutral sugars, uronic acids, Klason lignin, and noncore lignin phenolic acids), IVDMD, in vitro digestion kinetics of NDF, and monosaccharide digestibilities (24 and 120 h) were determined. Total fiber (TF) and NDF concentrations of all treatment residues were increased (P less than .05) over control substrates by AHP because of greater losses of cell solubles than of cell wall constituents. Hemicellulose:cellulose ratio in NDF of treatment residues was decreased (P less than .05) by AHP for all substrates, but the neutral sugar composition of TF did not agree with this preferential loss of hemicellulose components. Klason lignin, ADL, and esterified noncore lignin, especially ferulic acid, were reduced (P less than .05) by AHP, whereas etherified noncore lignin composition was unchanged. Treatment increased (P less than .05) IVDMD, extent of NDF digestion, and monosaccharide digestibilities of all crop residues. The rate of NDF digestion was increased (P less than .05) for the sugarcane residues but not for wheat straw. Alkaline hydrogen peroxide improved crop residue digestibility, probably as a result of the removal of core and noncore lignin fractions.

Animal Feed↗
PubMed1993

Is horseradish peroxidase a ligninolytic enzyme?

Structural modifications of spruce liginins catalyzed by plant horseradish peroxidase (HRP) were studied. Changes in lignin structure were characterized by monomeric composition determination and hydrodynamic property analysis. Results show that HRP modifies lignin monomeric composition without alteration of polymer gel permeation pattern. This indicates that HRP and LiP have similar but different biodegradative effects.

Biodegradation, Environmental↗
PubMed2001

Elucidation of new structures in lignins of CAD- and COMT-deficient plants by NMR.

Studying lignin-biosynthetic-pathway mutants and transgenics provides insights into plant responses to perturbations of the lignification system, and enhances our understanding of normal lignification. When enzymes late in the pathway are downregulated, significant changes in the composition and structure of lignin may result. NMR spectroscopy provides powerful diagnostic tools for elucidating structures in the difficult lignin polymer, hinting at the chemical and biochemical changes that have occurred. COMT (caffeic acid O-methyl transferase) downregulation in poplar results in the incorporation of 5-hydroxyconiferyl alcohol into lignins via typical radical coupling reactions, but post-coupling quinone methide internal trapping reactions produce novel benzodioxane units in the lignin. CAD (cinnamyl alcohol dehydrogenase) downregulation results in the incorporation of the hydroxycinnamyl aldehyde monolignol precursors intimately into the polymer. Sinapyl aldehyde cross-couples 8-O-4 with both guaiacyl and syringyl units in the growing polymer, whereas coniferyl aldehyde cross-couples 8-O-4 only with syringyl units, reflecting simple chemical cross-coupling propensities. The incorporation of hydroxycinnamyl aldehyde and 5-hydroxyconiferyl alcohol monomers indicates that these monolignol intermediates are secreted to the cell wall for lignification. The recognition that novel units can incorporate into lignins portends significantly expanded opportunities for engineering the composition and consequent properties of lignin for improved utilization of valuable plant resources.

Alcohol Oxidoreductases↗
PubMed2006

Raman imaging to investigate ultrastructure and composition of plant cell walls: distribution of lignin and cellulose in black spruce wood (Picea mariana).

A detailed understanding of the structural organization of the cell wall of vascular plants is important from both the perspectives of plant biology and chemistry and of commercial utilization. A state-of-the-art 633-nm laser-based confocal Raman microscope was used to determine the distribution of cell wall components in the cross section of black spruce wood in situ. Chemical information from morphologically distinct cell wall regions was obtained and Raman images of lignin and cellulose spatial distribution were generated. While cell corner (CC) lignin concentration was the highest on average, lignin concentration in compound middle lamella (CmL) was not significantly different from that in secondary wall (S2 and S2-S3). Images generated using the 1,650 cm(-1) band showed that coniferaldehyde and coniferyl alcohol distribution followed that of lignin and no particular cell wall layer/region was therefore enriched in the ethylenic residue. In contrast, cellulose distribution showed the opposite pattern-low concentration in CC and CmL and high in S2 regions. Nevertheless, cellulose concentration varied significantly in some areas, and concentrations of both lignin and cellulose were high in other areas. Though intensity maps of lignin and cellulose distributions are currently interpreted solely in terms of concentration differences, the effect of orientation needs to be carefully considered to reveal the organization of the wood cell wall.

Acrolein↗
PubMed1986

Effects of the fibre components pectin, cellulose, and lignin on bile salt metabolism and biliary lipid composition in man.

Randomised crossover studies in three separate groups of 10 healthy volunteers were undertaken to determine the effects of biliary lipid composition and bile salt metabolism of daily dietary supplementation for four weeks with the purified fibre components pectin (12 g/day), cellulose (15 g/day) and lignin (12 g/day). The subjects' biles were initially unsaturated with cholesterol and no significant changes in the lithogenic indices or mean percentages of cholesterol, phospholipid, or total bile acids after any of the supplements were observed. After pectin, the mean (+/- SD) percentage of cholic acid decreased significantly from 42.8 (+/- 10.8) to 39.0 (+/- 11.2), the mean (+/- SD) percentage of deoxycholic acid increased significantly from 18.2 (+/- 13.7) to 25.4 (+/- 13.5) and C14-deoxycholate metabolites were raised significantly by 65%. After cellulose, the mean (+/- SD) percentage of chenodeoxycholic acid was increased significantly from 33.6 (+/- 6.3) to 35.4 (+/- 7.0), the mean (+/- SD) percentage of deoxycholic acid decreased significantly from 18.6 (+/- 9.6) to 14.2 (+/- 8.3) and C14-deoxycholate metabolites halved. Lignin did not exert any significant effects. Though these results show that individual fibre components are associated with quite different effects on bile acid metabolism, in the short term no significant effect on biliary cholesterol saturation was observed in bile initially unsaturated with cholesterol. The bile acid changes most likely result from the different effects on colonic metabolism induced by the individual fibre components.

Adult↗
PubMed1978

Effects of experimental hypogravity on peroxidase and cell wall constituents in the dwarf marigold.

Dwarf Marigolds grown from seed under experimental hypogravity are modified in lignin content, hemicellulose composition, and peroxidase activity. The two conditions used, clinostats and flotation, induced changes differing in magnitude but qualitatively similar. Most responses on clinostats required corrections for vertical axis rotational effects, thus limiting the value of these instruments in free-fall simulation. These findings extend earlier observations suggesting that increased peroxidase and decreased lignin are characteristic of growth under experimental hypogravity.

Asteraceae↗