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Molecular characterization and functional expression of flavonol 6-hydroxylase


Molecular characterization and functional expression of flavonol 6-hydroxylase

Anzellotti, Dominique and Ibrahim, Ragai K. (2004) Molecular characterization and functional expression of flavonol 6-hydroxylase. BMC Plant Biology, 4 (20). ISSN 1471-2229

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Official URL: http://dx.doi.org/10.1186/1471-2229-4-20


Flavonoids, one of the major groups of secondary metabolites, play important roles in the physiology, ecology and defence of plants. Their wide range of activities is the result of their structural diversity that encompasses a variety of functional group substitutions including hydroxylations. The aromatic hydroxylation at position 6 of flavonols is of particular interest, since it is catalyzed by a 2-oxoglutarate-dependent dioxygenase (ODD), rather than a cytochrome P450-dependent monooxygenase. ODDs catalyze a variety of enzymatic reactions implicated in secondary metabolite biosynthesis.

A cDNA fragment encoding an ODD involved in the 6-hydroxylation of partially methylated flavonols, flavonol 6-hydroxylase (F6H), was isolated and characterized from Chrysosplenium americanum using internal peptide sequence information obtained from the native plant protein. This novel clone was functionally expressed in both prokaryotic and eukaryotic expression systems and exhibited ODD activity. The cofactor and cosubstrate requirements of the recombinant proteins are typical for ODDs, and the recombinant enzymes utilize 3,7,4'-trimethylquercetin as the preferred substrate. The genomic region encoding this enzyme possesses two introns at conserved locations for this class of enzymes and is present as a single copy in the C. americanum genome.

Recombinant F6H has been functionally expressed and characterized at the molecular level. The results demonstrate that its cofactor dependence, physicochemical characteristics and substrate preference compare well with the native enzyme. The N-terminal region of this protein is believed to play a significant role in catalysis and may explain the difference in the position specificity of the 6-hydroxylation reaction.

Divisions:Concordia University > Faculty of Arts and Science > Biology
Item Type:Article
Authors:Anzellotti, Dominique and Ibrahim, Ragai K.
Journal or Publication:BMC Plant Biology
Date:December 2004
  • Natural Sciences and Engineering Research Council of Canada
  • Fonds de recherche sur la nature et les technologies
Digital Object Identifier (DOI):10.1186/1471-2229-4-20
ID Code:6777
Deposited By: Danielle Dennie
Deposited On:13 Jul 2010 15:43
Last Modified:18 Jan 2018 17:29


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