TAILIEUCHUNG - Báo cáo khoa học: Flavonol 3-O-glycoside hydroxycinnamoyltransferases from Scots pine (Pinus sylvestris L.)

Flavonol 3-O-glucosides esterified with ferulic or p-coumaric acid at posi-tions 3¢¢ and 6¢¢ are the major UV-B screening pigments of the epidermal layer of Scots pine (Pinus sylvestris) needles. The last steps in the biosyn-thesis of these compounds are catalyzed by enzymes that transfer the acyl part of hydroxycinnamic acid CoA esters to flavonol 3-O-glucosides. A newly developed enzyme assay revealed three flavonol 3-O-glucoside hydroxycinnamoyltransferases (HCTs) in Scots pine needles with specifici-ties for positions 3¢¢,4¢¢ or 6¢¢. . | ềFEBS Journal Flavonol 3-O-glycoside hydroxycinnamoyltransferases from Scots pine Pinus sylvestris L. Florian Kaffarnik1 z Werner Heller1 Norbert Hertkorn2 and Heinrich Sandermann Jr1 1 Institute of BiochemicalPlant Pathology GSF-Research Center for Environment and Health Neuherberg Germany 2 Institute of EcologicalChemistry GSF-Research Center for Environment and Health Neuherberg Germany Keywords hydroxycinnamoyl-CoA flavonol3-O-glycoside hydroxycinnamoyltransferases diacylated flavonol3-O-glycosides Scots pine Pinus sylvestris Correspondence W Heller Institute of BiochemicalPlant Pathology GSF-Research Center for Environment and Health D-85764 Neuherberg Germany Fax 49 89 3187 3383 Tel 49 89 3187 3041 E-mail heller@ Website http Forschung Institute Present address Sainsbury Laboratory John Innes Centre Norwich NR4 7UH UK Received 24 November 2004 revised 14 January 2005 accepted 19 January 2005 Flavonol 3-ơ-glucosides esterified with ferulic or p-coumaric acid at positions 3 and 6 are the major UV-B screening pigments of the epidermal layer of Scots pine Pinus sylvestris needles. The last steps in the biosynthesis of these compounds are catalyzed by enzymes that transfer the acyl part of hydroxycinnamic acid CoA esters to flavonol 3-ơ-glucosides. A newly developed enzyme assay revealed three flavonol 3-ơ-glucoside hydroxycinnamoyltransferases HCTs in Scots pine needles with specificities for positions 3 4 or 6 . The positions of the acyl groups were identified by cochromatography with reference compounds and by NMR spectroscopy. The enzymes were characterized by molecular mass isoelectric point and also pH and temperature optima. Substrate specificities for flavonol glycosides and hydroxycinnamic acid CoA esters as well as kinetic properties of 3 - and 6 HCT suggested that acylation preferably occurs with glucosides and p-coumaroyl-CoA. In addition acylation takes place in a well-defined order beginning at position 6 followed by

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