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Proanthocyanidin Biosynthesis in Plants
Leucoanthocyanidin reductase (LAR) catalyzes the synthesis of catechin, an initiating monomer of condensed tannin or proanthocyanidin (PA) synthesis, from 3,4-cis-leucocyanidin and thus is the first committed step in PA biosynthesis. The enzyme was purified to near homogeneity from PA-rich leaves of...
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Published in: | The Journal of biological chemistry 2003-08, Vol.278 (34), p.31647-31656 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Leucoanthocyanidin reductase (LAR) catalyzes the synthesis of catechin, an initiating monomer of condensed tannin or proanthocyanidin (PA) synthesis, from 3,4-cis-leucocyanidin and thus is the first committed step in PA biosynthesis. The enzyme was purified to near homogeneity from PA-rich leaves of the legume Desmodium uncinatum (Jacq.) DC, partially sequenced and the corresponding cDNA cloned. The identity of the enzyme was confirmed by expressing active recombinant LAR in Escherichia coli and in tobacco and white clover. The enzyme is a monomer of 43 kDa (382 amino acids) and is most active synthesizing catechin (specific activity of ∼10 μmol min+1 mg of protein+1) but also synthesizes afzelechin and gallocatechin. LAR is most closely related to the isoflavone reductase group of plant enzymes that are part of the Reductase-Epimerase-Dehydrogenase (RED) family of proteins. Unlike all other plant isoflavone reductase homologues that are about 320 amino acids long, LAR has an additional 65-amino acid C-terminal extension whose function is not known. Curiously, although Arabidopsis makes PA, there is no obvious LAR orthologue in the Arabidopsis genome. This may be because Arabidopsis seems to produce only an epicatechin, rather than a dual catechin/epicatechin-based PA similar to many other plants. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M302783200 |