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For example, laccases play a role in the formation of lignin by promoting the oxidative coupling of monolignols, a family of naturally occurring phenols. [1] [2] Other laccases, such as those produced by the fungus Pleurotus ostreatus, play a role in the degradation of lignin, and can therefore be classed as lignin-modifying enzymes. [3]
Lignin-modifying enzymes benefit industry as they can break down lignin; a common waste product of the paper and pulp industry. These enzymes have been used in the refinement of poplar as lignin inhibits the enzymatic hydrolysis of treated poplar and Lignin-modifying enzymes can efficiently degrade the lignin thus fixing this problem. [4]
The enzyme phenylalanine ammonia lyase (EC 4.3.1.24) catalyzes the conversion of L-phenylalanine to ammonia and trans-cinnamic acid.: [1] L -phenylalanine = trans -cinnamate + NH 3 Phenylalanine ammonia lyase (PAL) is the first and committed step in the phenyl propanoid pathway and is therefore involved in the biosynthesis of the polyphenol ...
The enzyme is notable for its promiscuity, affecting the O-demethylation of a range of substrates, including lignin. It is a heterodimeric protein derived from the products of two genes. The component proteins are a cytochrome P450 enzyme (encoded by the gcoA gene from the family CYP255A) and a three-domain reductase (encoded by the gcoB gene ...
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. [1] 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. [2]
Lignin is found to be degraded by enzyme lignin peroxidases produced by some fungi like Phanerochaete chrysosporium. The mechanism by which lignin peroxidase (LiP) interacts with the lignin polymer involves veratrole alcohol , which is a secondary metabolite of white rot fungi that acts as a cofactor for the enzyme.
Phenylalanine and tyrosine are the precursors used in the phenylpropanoids biosynthesis. The phenylpropanoids are then used to produce the flavonoids, coumarins, tannins and lignin. The first enzyme involved is phenylalanine ammonia-lyase (PAL) that converts L-phenylalanine to trans-cinnamic acid and ammonia.
It is the precursor to ferulic acid, coniferyl alcohol, and sinapyl alcohol, all of which are significant building blocks in lignin. [2] The transformation to ferulic acid is catalyzed by the enzyme caffeate O-methyltransferase. Caffeic acid and its derivative caffeic acid phenethyl ester (CAPE) are produced in many kinds of plants. [14] [15] [16]