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Xanthine dehydrogenase and cytokinin metabolism

Laborato ř růstových regulátorů , PřF UP Olomouc a ÚEB AV ČR Laborato ry of Growth Regulators , Faculty of Science, Palacký University in Olomouc and Institute of Experimental Botany ASCR, Czech Republic. Xanthine dehydrogenase and cytokinin metabolism. Jitka Frébortová.

francesca-sereno
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Xanthine dehydrogenase and cytokinin metabolism

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  1. Laboratořrůstových regulátorů, PřF UP Olomouc a ÚEB AV ČRLaboratory of Growth Regulators, Faculty of Science, Palacký University in Olomouc and Institute of Experimental Botany ASCR, Czech Republic Xanthine dehydrogenase and cytokinin metabolism Jitka Frébortová Cytokinin meeting, Olomouc, September 8, 2011

  2. Xanthine oxidoreductase XO/XDH XO/XDH Hypoxanthine Xanthine Uric acid Werner and Witte (2011) Trends Plant Sci.16, 381-387.

  3. Cytokinins described also as inhibitors of bovine milk XO Conversion of cytokinins to 8-hydroxyderivatives confirmed also in rhizobacterium Serratia protemaculans Interaction of cytokinins with bovine milk xanthine oxidase XO XO lmax = 269 nm lmax = 275 nm lmax = 306 nm (pH 7, iP, tZ) Chen et al. (1975) Biochemistry14, 3088-3093. Sheu et al. (1996)Anticancer Res. 16, 3571-3576. Sheu et al. (1997)Anticancer Res. 17, 1043-1050. Taylor et al. (2006) Phytochemistry67, 1887-1894.

  4. Plant xanthine dehydrogenase and cytokinin metabolism • Is AtXDH1 converting cytokinins? • Are cytokinins substrates or inhibitors of XORs? • Are the relevant metabolites present in plants? • Biological activity of 8-OH and 2,8-OH cytokinins

  5. Cytokinin free bases are substrates of AtXDH1 and milk XO Kinetic constants for the oxidation of cytokinins and xanthine by AtXDH1 and milk XO Chromatographic analysis of t-zeatin oxidation by AtXDH1 275 nm 310 nm N9-ribosides, ribotides and glucosides are not oxidized

  6. N9-substituted cytokinins do not interact with AtXDH1 and milk XO Effect of N9–substituted cytokinins on xanthine oxidation by AtXDH1 and milk XO a Data taken from Sauer et al. (2002) Plant Physiol. Biochem.40, 393-400.

  7. Cytokinins may interfere with normal purine metabolism Inhibition of uric acid formation by AtXDH1 using cytokinins as inhibitors

  8. Plant xanthine dehydrogenase and cytokinin metabolism • Is AtXDH1 converting cytokinins? • Are cytokinins substrates or inhibitors of XORs? • Are the relevant metabolites present in plants? • Is there any physiological function for interaction of cytokinins with XDH? • Biological activity of 8-OH and 2,8-OH cytokinins

  9. Acknowledgements Palacký University Palacký University/ Institute of Experimental Botany Department of Biochemistry Laboratory of Growth Regulators Petr Tarkowski Pavel Jaworek Lukáš Spíchal Technische Universität Braunschweig Institut für Pflanzenbiologie Florian Bittner

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