Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are polymers made by cross-linking phenolic precursors.
Eugenol is an allyl chain-substituted guaiacol, a member of the allylbenzene class of chemical compounds. It is a colorless to pale yellow, aromatic oily liquid extracted from certain essential oils especially from clove, nutmeg, cinnamon, basil and bay leaf. It is present in concentrations of 80–90% in clove bud oil and at 82–88% in clove leaf oil. Eugenol has a pleasant, spicy, clove-like scent. The name is derived from Eugenia caryophyllata, the former Linnean nomenclature term for cloves. The currently accepted name is Syzygium aromaticum.
Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid. This yellow solid consists of both phenolic and acrylic functional groups. It is found in all plants because it is an intermediate in the biosynthesis of lignin, one of the principal components of woody plant biomass and its residues.
Guaiacol is a naturally-occurring organic compound with the formula C6H4(OH)(OCH3). Although it is biosynthesized by a variety of organisms, this aromatic oil is usually derived from guaiacum or wood creosote. It is also found in essential oils from celery seeds, tobacco leaves, orange leaves, and lemon peels. The pure substance is colorless, but samples become yellow upon exposure to air and light. Guaiacol is present in wood smoke, resulting from the pyrolysis of lignin. The compound contributes to the flavor of many substances such as whisky and roasted coffee.
Coniferyl alcohol is an organic compound with the formula HO(CH3O)C6H3CH=CHCH2OH. A colourless or white solid, it is one of the monolignols, produced via the phenylpropanoid biochemical pathway. When copolymerized with related aromatic compounds, coniferyl alcohol forms lignin or lignans. Coniferin is a glucoside of coniferyl alcohol. Coniferyl alcohol is an intermediate in biosynthesis of eugenol and of stilbenoids and coumarin. Gum benzoin contains significant amount of coniferyl alcohol and its esters. It is found in both gymnosperm and angiosperm plants. Sinapyl alcohol and paracoumaryl alcohol, the other two lignin monomers, are found in angiosperm plants and grasses.
Dirigent proteins are members of a class of proteins which dictate the stereochemistry of a compound synthesized by other enzymes. The first dirigent protein was discovered in Forsythia intermedia. This protein has been found to direct the stereoselective biosynthesis of (+)-pinoresinol from coniferyl alcohol monomers:
The phenylpropanoids are a diverse family of organic compounds that are synthesized by plants from the amino acids phenylalanine and tyrosine. Their name is derived from the six-carbon, aromatic phenyl group and the three-carbon propene tail of coumaric acid, which is the central intermediate in phenylpropanoid biosynthesis. From 4-coumaroyl-CoA emanates the biosynthesis of myriad natural products including lignols, flavonoids, isoflavonoids, coumarins, aurones, stilbenes, catechin, and phenylpropanoids. The coumaroyl component is produced from cinnamic acid.
Molybdopterins are a class of cofactors found in most molybdenum-containing and all tungsten-containing enzymes. Synonyms for molybdopterin are: MPT and pyranopterin-dithiolate. The nomenclature for this biomolecule can be confusing: Molybdopterin itself contains no molybdenum; rather, this is the name of the ligand that will bind the active metal. After molybdopterin is eventually complexed with molybdenum, the complete ligand is usually called molybdenum cofactor.
Syringol is the organic compound with the formula HO(CH3O)2C6H3. The molecule is a phenol, with methoxy groups in the flanking (2 and 6) positions. It is the symmetrically dimethylated derivative of pyrogallol. It is a colorless solid, although typical samples are brown owing to air-oxidized impurities. Together with guaiacol, syringol and its derivatives are produced by the pyrolysis of lignin. Specifically, syringol is derived from the thermal decomposition of the sinapyl alcohol component. As such, syringol is an important component of wood smoke.
Monolignols, also called lignols, are the source materials for biosynthesis of both lignans and lignin and consist mainly of paracoumaryl alcohol (H), coniferyl alcohol (G) and sinapyl alcohol (S). These monolignols differ in their degree of methoxilation of the aromatic ring.
Sinapyl alcohol is an organic compound structurally related to cinnamic acid. It is biosynthetized via the phenylpropanoid biochemical pathway, its immediate precursor being sinapaldehyde. This phytochemical is one of the monolignols, which are precursor to lignin or lignans. It is also a biosynthetic precursor to various stilbenoids and coumarins.
In enzymology, aldose reductase is a cytosolic NADPH-dependent oxidoreductase that catalyzes the reduction of a variety of aldehydes and carbonyls, including monosaccharides. It is primarily known for catalyzing the reduction of glucose to sorbitol, the first step in polyol pathway of glucose metabolism.
In enzymology, an aryl-alcohol dehydrogenase (NADP+) (EC 1.1.1.91) is an enzyme that catalyzes the chemical reaction
In enzymology, a dihydrokaempferol 4-reductase (EC 1.1.1.219) is an enzyme that catalyzes the chemical reaction
In enzymology, a histidinol dehydrogenase (HIS4) (HDH) (EC 1.1.1.23) is an enzyme that catalyzes the chemical reaction
In enzymology, an aspartate-semialdehyde dehydrogenase is an enzyme that is very important in the biosynthesis of amino acids in prokaryotes, fungi, and some higher plants. It forms an early branch point in the metabolic pathway forming lysine, methionine, leucine and isoleucine from aspartate. This pathway also produces diaminopimelate which plays an essential role in bacterial cell wall formation. There is particular interest in ASADH as disabling this enzyme proves fatal to the organism giving rise to the possibility of a new class of antibiotics, fungicides, and herbicides aimed at inhibiting it.
Cinnamoyl-CoA reductase (EC 1.2.1.44), systematically named cinnamaldehyde:NADP+ oxidoreductase (CoA-cinnamoylating) but commonly referred to by the acronym CCR, is an enzyme that catalyzes the reduction of a substituted cinnamoyl-CoA to its corresponding cinnamaldehyde, utilizing NADPH and H+ and releasing free CoA and NADP+ in the process. Common biologically relevant cinnamoyl-CoA substrates for CCR include p-coumaroyl-CoA and feruloyl-CoA, which are converted into p-coumaraldehyde and coniferaldehyde, respectively, though most CCRs show activity toward a variety of other substituted cinnamoyl-CoA's as well. Catalyzing the first committed step in monolignol biosynthesis, this enzyme plays a critical role in lignin formation, a process important in plants both for structural development and defense response.
3α-Hydroxysteroid dehydrogenase is an enzyme that in humans is encoded by the AKR1C4 gene. It is known to be necessary for the synthesis of the endogenous neurosteroids allopregnanolone, THDOC, and 3α-androstanediol. It is also known to catalyze the reversible conversion of 3α-androstanediol (5α-androstane-3α,17β-diol) to dihydrotestosterone and vice versa.
The aldehyde oxidase and xanthine dehydrogenase, a/b hammerhead domain is an evolutionary conserved protein domain.
Coniferyl aldehyde is an organic compound with the formula HO(CH3O)C6H3CH=CHCHO. It is a derivative of cinnamaldehyde, featuring 4-hydroxy and 3-methoxy substituents. It is a major precursor to lignin.
