Journal of Plant Biochemistry & Physiology
Open Access
ISSN: 2329-9029
ISSN: 2329-9029
Plant Biochemistry Laboratory, Department of Biology, Concordia University, 7141 Sherbrooke Street West, Montréal, Québec, H4B 1R6, Canada
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 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