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Biochimie. 2008 May;90(5):781-9. doi: 10.1016/j.biochi.2007.12.004. Epub 2007 Dec 28.

Biochemical and molecular characterization of a quercetinase from Penicillium olsonii.

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Laboratoire BiosCiences FRE CNRS 3005, case 432, Faculté des Sciences et Techniques de Saint Jérôme, Aix-Marseille Université, avenue Escadrille Normandie-Niemen, 133397 Marseille Cedex 20, France.


Quercetinase (quercetin 2,3-dioxygenase, EC is produced by various filamentous fungi when grown on rutin as the sole carbon and energy source. From a rutin based liquid culture of Penicillium olsonii, we purified a quercetinase with a specific activity of 175U mg(-1). The enzyme is a monomeric glycoprotein of approximately 55 kDa, containing 0.9+/-0.1 copper atoms per protein. Its substrate specificity is restricted to the flavonol family of flavonoids. It is completely inhibited by diethyldithiocarbamate at a concentration of 100 nM and 1H-2-benzyl-3-hydroxy-4-oxoquinolin is a competitive inhibitor with a K(I) of 4 microM. The cDNA poquer1 was cloned and sequenced. It encodes a 365 amino acids long enzyme with a strong sequence identity with the Aspergillus japonicus quercetinase (Q7SIC2). Like the enzyme from A. japonicus, only one of the two cupin domains of the Penicillium olsonii quercetinase is able to bind a metal atom.

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