title: Occurrence and characterization of a UDP-glucose:hydroxamic acid glucosyltransferase isolated from wheat (Triticum aestivum) seedlings.
abstract: Cyclic hydroxamic acid glucosides are present at high concentrations immediately after germination in wheat (Triticum aestivum L.). Changes in the activity of UDP-Glucose:cyclic hydroxamic acid glucosyltransferase (EC 2.4.1.-) in wheat were investigated using the cyclic hydroxamic acids 2.4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) and its 7-methoxy derivative (DIMBOA) as sugar acceptors. Glucosyltransferase activity on both substrates was detected in dry seeds, with activity increasing after imbibition, peaking in shoots and roots 36-48 hours after imbibition and decreasing thereafter. The transience of glucosyltransferase activity was concurrent with the transient occurrence of the hydroxamic acid glucosides [Nakagawa E., Amano T., Hirai N., and Iwamura H. (1995) Phytochemistry 38, 1349-1354], suggesting that glucosyltransferases regulate the accumulation of hydroxamic acid glucosides in wheat seedlings. Two peaks in activity of UDP-Glucose:DIMBOA glucosyltransferase were detected using a Mono Q column, indicating the presence of at least two isozymes of this glucosyltransferase. The enzyme in the major peak was purified about 1500-fold and shown to be in a monomeric form with a molecular mass of 47 or 49 kDa. The enzyme reacted strongly with DIMBOA, less so with DIBOA. The enzyme of the minor peak on the Mono Q chromatogram, which was also a monomeric enzyme with a molecular mass of 47 kDa, showed similar substrate specificity to that of the major peak enzyme.
authors: Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University. sue@kais.kyoto-u.ac.jp
authors: M
authors: M
authors: Sue
authors: A
authors: A
authors: Ishihara
authors: H
authors: H
authors: Iwamura
mesh_terms: D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005964:Glucosyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D018520:Plant Shoots / Q000201:enzymology; D013379:Substrate Specificity; D014908:Triticum / Q000201:enzymology* / Q000254:growth & development
chemical_list: D005964:Glucosyltransferases; C420973:UDP-glucose hydroxamic acid glucosyltransferase