M. Sue et al., Occurrence and characterization of a UDP-glucose : hydroxamic acid glucosyltransferase isolated from wheat (Triticum aestivum) seedlings, Z NATURFO C, 55(9-10), 2000, pp. 701-707
Citations number
16
Categorie Soggetti
Biochemistry & Biophysics
Journal title
ZEITSCHRIFT FUR NATURFORSCHUNG C-A JOURNAL OF BIOSCIENCES
Cyclic hydroxamic acid glucosides are present at high concentrations immedi
ately after germination in wheat (Triticum aestivum L.). Changes in the act
ivity of UDP-Glucose:cyclic hydroxamic acid glucosyltransferase (EC 2.4.1.-
) in wheat were investigated using the cyclic hydroxamic acids 2,4-dihydrox
y-1,4-benzoxazin-3-one (DIBOA) and its 7-methoxy derivative (DIMBOA) as sug
ar accepters. Glucosyltransferase activity on both substrates was detected
in dry seeds, with activity increasing after imbibition, peaking in shoots
and roots 36-45 hours after imbibition and decreasing thereafter. The trans
ience of glucosyltransferase activity was concurrent with the transient occ
urrence of the hydroxamic acid glucosides [Nakagawa E., Amano T., PIirai N.
, and Iwamura H. (1995) Phytochemistry 38, 1349-1354], suggesting that gluc
osyltransferases regulate the accumulation of hydroxamic acid glucosides in
wheat seedlings. Two peaks in activity of UDP-Glucose:DIMBOA glucosyltrans
ferase were detected using a Mono Q column, indicating the presence of at l
east 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 mo
lecular 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, wh
ich was also a monomeric enzyme with a molecular mass of 47 kDa, showed sim
ilar substrate specificity to that of the major peak enzyme.