Journal of Plant Biochemistry & Physiology
Open Access

Amira Moheb

Publications

• Research Article
  Tobacco Ntomt2 Revisited: Multiple O-Methylation of Quercetin is Catalyzed by a Single Gene Product
  Author(s): Jian-Min Zhou, Amira Moheb and Ragai K IbrahimJian-Min Zhou, Amira Moheb and Ragai K Ibrahim
  
  Tobacco NtOMT2 was previously reported as an inducible, o-diphenol O-methyltransferase (OMT) that exhibits similar preferences towards quercetin and caffeic acid as substrates. In this report, we further examine the substrate specificity of  NtOMT2 based on enzyme assays, kinetic data and phylogenetic analysis. We demonstrate that NtOMT2 is a flavonol OMT that catalyzes multiple O-methylation of the flavonol quercetin giving rise to its mono-, di- and trimethyl ether derivatives. Mono-methylation of quercetin on the 3-, 3′-/4′- and 7-hydroxyl groups occurs in a random fashion according to the physio-chemical properties of their hydroxyl groups, together with their similar binding energies in the NtOMT2 binding pocket. Homology modeling of NtOMT2 with the Medicago sativa COMT as a template indicates that the H-bonding network between the functional hydrox.. View More»
  DOI: 10.35248/2090-7214.13.1.107

  Abstract PDF

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