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Encyclopedia > Lignin

Lignin (sometimes "lignen") is a chemical compound (complex, highly cross-linked aromatic polymer) that is most commonly derived from wood and is an integral part of the cell walls of plants, especially in tracheids, xylem fibres and sclereids. A chemical compound is a chemical substance of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... A polymer is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... Trunks A tree trunk as found at the Veluwe, The Netherlands Wood is a solid material derived from woody plants, notably trees but also shrubs. ... A cell wall is a fairly rigid layer surrounding a cell, located external to the cell membrane, that provides the cell with structural support, protection, and a filtering mechanism. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... Tracheids are elongated cells in the xylem of vascular plants, serving in the transport of water. ...


The term lignin was introduced in 1819 and is derived from the Latin word lignum.[1] It is one of most abundant organic compounds on earth after cellulose and chitin. Lignin makes up about one-quarter to one-third of the dry mass of wood. It has several unusual properties for being a biopolymer, such as having a network structure and lacking a defined primary structure. An organic compound is any of a large class of chemical compounds whose molecules contain carbon, with exception of carbides, carbonates and carbon oxides. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... Structure of the chitin molecule, showing two of the N-Acetylglucosamine units that repeat to form long chains in beta-1,4 linkage. ... Trunks A tree trunk as found at the Veluwe, The Netherlands Wood is a solid material derived from woody plants, notably trees but also shrubs. ...

Contents

Biological function

Lignin fills the spaces in the cell wall between cellulose, hemicellulose and pectin components. It is covalently linked to hemicellulose. It also forms covalent bonds to polysaccharides and thereby crosslinks different plant polysaccharides. A cell wall is a fairly rigid layer surrounding a cell, located external to the cell membrane, that provides the cell with structural support, protection, and a filtering mechanism. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... A hemicellulose can be any of several heteropolymers (matrix polysaccharides) present in almost all cell walls along with cellulose. ... This article or section does not cite any references or sources. ... Covalent bonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons between atoms, in order to produce a mutual attraction, which holds the resultant molecule together. ... A hemicellulose can be any of several heteropolymers (matrix polysaccharides) present in almost all cell walls along with cellulose. ...


It confers mechanical strength to the cell wall (stabilizing the mature cell wall) and therefore the entire plant. It is particularly abundant in compression wood, but curiously scarce in tension wood. A cell wall is a fairly rigid layer surrounding a cell, located external to the cell membrane, that provides the cell with structural support, protection, and a filtering mechanism. ... Reaction wood is formed in response to mechanical stress, and helps to position newly formed parts of the plant in an optimal position. ... Reaction wood is formed in response to mechanical stress, and helps to position newly formed parts of the plant in an optimal position. ...


Lignin plays a crucial part in conducting water in plant stems. The polysaccharide components of plant cell walls are highly hydrophilic and thus permeable to water, whereas lignin is more hydrophobic. The crosslinking of polysaccharides by lignin is an obstacle for water absorption to the cell wall. Thus, lignin makes it possible for the plant's vascular tissue to conduct water efficiently. Lignin is present in all vascular plants, but not in bryophytes, supporting the idea that the main function of lignin is related to water transport. Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... A cell wall is a fairly rigid layer surrounding a cell, located external to the cell membrane, that provides the cell with structural support, protection, and a filtering mechanism. ... The adjective hydrophilic describes something that likes water (from Greek hydros = water; philos = friend). ... In chemistry, hydrophobic or lipophilic species, or hydrophobes, tend to be electrically neutral and nonpolar, and thus prefer other neutral and nonpolar solvents or molecular environments. ...


Lignin is indigestible by mammalian and other animal enzymes, but some fungi and bacteria are able to biodegrade the polymer. The details of the reaction scheme of the biodegradation are not fully understood to date. These reactions depend on the type of wood decay - in fungi either brown rot, soft rot or white rot. It is suggested that enzymes that employ free radicals for depolymerization reactions are employed.[2] Well understood lignolytic enzymes are manganese peroxidase, lignin peroxidase and cellobiose dehydrogenase. Furthermore, because of its cross-linking with the other cell wall components, it minimizes the accessibility of cellulose and hemicellulose to microbial enzymes. Hence, lignin is generally associated with reduced digestibility of the over all plant biomass. It is also suggested that lignin may help boost plant's defense against pathogens and pests. For example an infection by a fungus causes the plant to deposit more lignin near the infection site[citation needed]. Brown rot (Monilinia fructicola) is a fungal condition that attacks stone fruit, commonly affecting peaches, pears, apples and plums. ... A pathogen (literally birth of pain from the Greek παθογένεια) is a biological agent that can cause disease to its host. ... Look up Pest in Wiktionary, the free dictionary The primary meaning of pest is an animal which has characteristics which people regard as being injurious or harmful. ... For the fictional character, see Fungus the Bogeyman. ...


Economic significance

Highly lignified wood is durable and therefore a good raw material for many applications. It is also an excellent fuel, since lignin yields more energy when burned than cellulose. However, lignin is detrimental to paper manufacture and must be removed from pulp before paper can be manufactured. This is costly both in terms of energy and environment. Trunks A tree trunk as found at the Veluwe, The Netherlands Wood is a solid material derived from woody plants, notably trees but also shrubs. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... A blank sheet of paper Paper is a commodity of thin material produced by the amalgamation of fibers, typically vegetable fibers composed of cellulose, which are subsequently held together by hydrogen bonding. ... International Paper Company Wood pulp is the most common material used to make paper. ...


In the sulfite and sulfate (also called kraft) chemical pulping processes, lignin is removed from wood pulp as sulphates. These materials have several uses: Sulfites (also sulphite) are compounds that contain the sulfite ion SO32−. They are often used as preservatives in wines (to prevent spoilage and oxidation), dried fruits, and dried potato products. ... In inorganic chemistry, a sulfate (IUPAC-recommended spelling; also sulphate in British English) is a salt of sulfuric acid. ... Sulfate is the IUPAC name for the SO42- ion, consisting of a central sulfur atom single bonded to four tetrahedrally oriented oxygen atoms. ...

  • Additives in specialty oil field applications and agricultural chemicals
  • Environmentally friendly dust suppression agent for roads

The first investigations into commercial use of lignin were done by Marathon Corporation in Rothschild, Wisconsin (USA), starting in 1927. The first class of products which showed promise were leather tanning agents. The lignin chemical business of Marathon is now known as LignoTech USA, Inc., and is owned by the Norwegian company, Borregaard. In the most general sense of the word, cement is a binder, a substance which sets and hardens independently, and can bind other materials together. ... Water treatment in a general sense reffers to the treatement of water to make it more acceptable for what will be done with it (either usage or discharge into the environment). ... Look up dye in Wiktionary, the free dictionary. ... Pumpjack pumping an oil well near Lubbock, Texas Ignacy Łukasiewicz - inventor of the refining of kerosene from crude oil. ... Vanillin, methyl vanillin, or 4-hydroxy-3-methoxybenzaldehyde, is an organic compound with the molecular formula C8H8O3. ... Dimethyl sulfoxide (DMSO) is the chemical compound (CH3)2SO. This colorless liquid is an important dipolar aprotic solvent. ... Grain alcohol redirects here. ... Binomial name Candida utilis (Henneberg) Lodder & Kreger-van Rij Torula (Latin name: Candida utilis; formerly Torulopsis utilis, Torula utilis) is a species of yeast. ... Xylitol, also called wood sugar or birch sugar, is a five-carbon sugar alcohol that is used as a sugar substitute. ... Humic acid is one of the major components of humic substances which are dark brown and major constituents of soil organic matter humus that contributes to soil chemical and physical quality and are also precursors of some fossil fuels. ... Rothschild is a village located in Marathon County, Wisconsin. ... Official language(s) None Capital Madison Largest city Milwaukee Area  Ranked 23rd  - Total 65,498 sq mi (169,790 km²)  - Width 260 miles (420 km)  - Length 310 miles (500 km)  - % water 17  - Latitude 42°30N to 47°3N  - Longitude 86°49W to 92°54W Population  Ranked... Year 1927 (MCMXXVII) was a common year starting on Saturday (link will display full calendar) of the Gregorian calendar. ... This page is about making leather. ... Borregaard Norwegian company, established in 1889 in Sarpsborg, Norway. ...


Structure and biosynthesis

Lignin structure
Lignin structure
Structure of a small piece of lignin polymer
Structure of a small piece of lignin polymer
Structures of the three commonly occurring monolignols
Polymerisation of coniferyl alcohol to lignin. The reaction has two alternative routes catalysed by two different oxidative enzymes, peroxidases or oxidases.
Polymerisation of coniferyl alcohol to lignin. The reaction has two alternative routes catalysed by two different oxidative enzymes, peroxidases or oxidases.

Lignin is a large, cross-linked macromolecule with molecular mass in excess of 10,000 u. It is relatively hydrophobic and aromatic in nature. The molecular weight in nature is difficult to measure, since it is fragmented during preparation. The molecule consists of various types of substructures which appear to repeat in random manner. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links LigninStructure. ... Image File history File links LigninStructure. ... Image File history File links MonolignolStructure. ... Image File history File links MonolignolStructure. ... Image File history File links LigninPolymerisation. ... Image File history File links LigninPolymerisation. ... Coniferyl alcohol is a colourless crystalline solid. ... In chemistry and biology, catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance, called a catalyst, that is itself not consumed by the overall reaction. ... Glutathione Peroxidase 1 A peroxidase (eg. ... An oxidase is any enzyme that catalyzes an oxidation/reduction reaction involving molecular oxygen (O2) as the electron acceptor. ... A macromolecule is a large molecule with a large molecular mass bonded covalently, but generally the use of the term is restricted to polymers and molecules which structurally include polymers. ... The molecular mass (abbreviated Mr) of a substance, formerly also called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... The atomic mass unit (amu), unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic masses and molecular masses. ... In chemistry, hydrophobic or lipophilic species, or hydrophobes, tend to be electrically neutral and nonpolar, and thus prefer other neutral and nonpolar solvents or molecular environments. ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... In science, a molecule is a group of atoms in a definite arrangement held together by chemical bonds. ...


Lignin biosynthesis begins with the synthesis of monolignols. The starting material is the amino acid phenylalanine. The first reactions in the biosynthesis are shared with the phenylpropanoid pathway, and monolignols are considered to be a part of this group of compounds. There are three main monolignols: coniferyl alcohol, sinapyl alcohol and paracoumaryl alcohol. (There are a number of other monolignols present in special plants or in low concentration.) Different plants use different monolignols. For example, gymnosperms as Norway spruce have a lignin that consist almost entirely coniferyl alcohol. Dicotyledonic lignin is a mixture of conifyl alcohol and sinapyl alcohol (normally more of the latter), and monocotylednic lignin is a mixure of all three monolignols. Some monocotyledons have mostly coniferyl alcohol (as many grasses), while other have mainly sinapyl alcohols, as some palms. Monolignols are synthesized in the cytosol as glucosides. The glucose is added to the monolignol to make them water soluble and to reduce their toxicity. The glucosides are transported through the cell membrane to the apoplast. The glucose is then removed and the monolignols are polymerized into lignin. Biosynthesis is a phenomenon where chemical compounds are produced from simpler reagents. ... Structures of the three commonly occurring monolignols Monolignols are phytochemicals acting as source materials for biosynthesis of lignin. ... Phenylalanine is one of the standard amino acids. ... Phe redirects here. ... Biosynthesis is a phenomenon where chemical compounds are produced from simpler reagents. ... Phenylpropanoids are a class of plant-derived organic compounds that are biosynthesized from the amino acid phenylalanine. ... Coniferyl alcohol is a colourless crystalline solid. ... Sinapyl alcohol Sinapyl alcohol, also called sinapoyl alcohol or 4-(3-hydroxy-1-propenyl)-2,6-dimethoxy-phenol, is a phytochemical, one of the monolignols. ... p-coumaryl alcohol Paracoumaryl alcohol, also called p-coumaryl alcohol, 4-coumaryl alcohol, 4-hydroxycinnamyl alcohol, or 4-(3-hydroxy-1-propenyl)phenol, is a phytochemical, one of the monolignols. ... u fuck in ua ... Binomial name Picea abies (L.) H. Karst. ... Coniferyl alcohol is a colourless crystalline solid. ... The cytosol (cf. ... A glucoside is a glycoside that is derived from glucose. ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... A glucoside is a glycoside that is derived from glucose. ... The cell membrane (also called the plasma membrane or plasmalemma) is a semipermeable lipid bilayer common to all living cells. ... Within a plant, the apoplast is the free diffusional space outside the plasma membrane. ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ...


The polymerisation step, that is a radical-radical coupling, is catalysed by oxidative enzymes. Both peroxidase and laccase enzymes are present in the plant cell walls, and it is not known whether one or both of these groups participates in the polymerisation. Low molecular weight oxidants might also be involved. The oxidative enzyme catalyses the formation of monolignol radicals. These radicals are often said to undergo uncatalyzed coupling to form the lignin polymer, but this hypothesis has been recently challenged.[3] Polymerization is the formation of long, repeating organic polymer chains. ... In chemistry and biology, catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance, called a catalyst, that is itself not consumed by the overall reaction. ... Polymerisation of coniferyl alcohol to lignin. ... Glutathione Peroxidase 1 A peroxidase (eg. ... Laccases (EC 1. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... A cell wall is a more or less solid layer surrounding a cell. ... Polymerization is the formation of long, repeating organic polymer chains. ... In chemistry and biology, catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance, called a catalyst, that is itself not consumed by the overall reaction. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... A polymer is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ...


Pyrolysis

Pyrolysis of lignin, eg. during combustion, yields a range of products, of which the most characteristic ones are methoxy phenols. Of those, the most important are guaiacol and syringol and their derivatives; their presence can be used to trace a smoke source to a wood fire. In cooking, lignin in the form of hardwood is an important source of these two chemicals which impart the characteristic aroma and taste to smoked foods. Simple sketch of pyrolysis chemistry Pyrolysis usually means the chemical decomposition of organic materials by heating in the absence of oxygen or any other reagents, except possibly steam. ... A combustion reaction taking place in a igniting match Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. ... In chemistry, the methoxy prefix indicates the function group consisting of the methyl group and oxygen. ... In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxyl group (-OH) attached to an aromatic hydrocarbon group. ... Chemical structure of guaiacol Guaiacol, or 2-methoxyphenol, is a natural organic compound with the molecular formula C7H8O2. ... Syringol Syringol, also called 2,6-dimethoxyphenol, 1,3-dimethoxy-2-hydroxybenzene, 2-hydroxy-1,3-dimethoxybenzene, or pyrogallol 1,3-dimethyl ether, is an organic compound. ... Smoke from a wildfire Smoke is a suspension in air (aerosol) of small particles resulting from incomplete combustion of a fuel. ... Cooking is the act of preparing food for ingestion. ... Image:Fagus wood. ... Wikibooks Cookbook has more about this subject: Smoking Smoking is the process of preserving, cooking, or flavoring food by exposing it to the smoke from burning or smoldering plant materials, most often wood. ...


Ligninase

Ligninase is the lignin enzyme, a haemoprotein from phanerochaete chrysosporium with a variety of lignin-degrading reactions, all dependent on hydrogen peroxide; incorporates molecular oxygen into the products. A more used name for this enzyme is lignin peroxidase. There are also several other microbial enzymes that are believed to be involved in lignin biodegradation, such as manganese peroxidase, laccase and cellobiose dehydrogenase. Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Laccases (EC 1. ...


The registry number is EC 1.14.99 EC may stand for: EC is the IATA code for Avialeasing Aviation, an airline Early childhood education Eastern Caribbean dollar, sometimes referred to as the (EC$) EC Comics, a now defunct comic book company EC numbers (Enzyme Commission numbers) are used for the numerical classification of enzymes EC number or...


References

  1. ^ Sjöström, E. (1993). Wood Chemistry: Fundamentals and Applications. Academic Press. 
  2. ^ Carlile, Michael J.; Sarah C. Watkinson (1994). The fungi. Academic Press. ISBN 0-12-159959-0. 
  3. ^ Davin, L.B.; Lewis, N.G. (2005). "Lignin primary structures and dirigent sites". Current Opinion in Biotechnology 16: 407-415. 

Academic Press (London, New York and San Diego) was an academic book publisher that is now part of Elsevier. ... Academic Press (London, New York and San Diego) was an academic book publisher that is now part of Elsevier. ...

External links

  • Biosynthesis pathway of lignin
  • The Lignin Institute A promotional site by a trade association of lignin manufacturers and users.

  Results from FactBites:
 
Lignin - definition of Lignin in Encyclopedia (180 words)
Lignin is a chemical compound that is an integral part of the cell walls of some cells, eg tracheids, xylary fibres and sclereids of plants.
Lignin is formed by the irreversible removal of water from sugars, creating aromatic compounds through the phenylpropanoid pathway.
Lignin is removed from wood pulp before it is turned into paper, and the extracted lignin is used as a binder in particleboard, adhesive for linoleum, and raw material for processing into chemicals (such as DMSO and vanillin).
Encyclopedia: Lignin (780 words)
Lignin is thought to act as a kind of glue in the plant cell walls and give plants very effective protection against parasite attack.
In the chemical pulping process, lignin is removed from wood pulp before it is turned into paper, and the extracted lignin is used as a binder in particleboard, adhesive for linoleum, and raw material for processing into chemicals (such as DMSO and vanillin).
Lignin is a group of chemical compounds that is used in the cell walls of plants to create wood.
  More results at FactBites »

 
 

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