Flavonol-3-O-glucoside L-rhamnosyltransferase () is an enzyme that catalyzes the general chemical reaction
UDP-L-rhamnose + a flavonol 3-O-D-glucoside UDP + a flavonol 3-O-[beta-L-rhamnosyl-(1->6)-beta-D-glucoside]
The two substrates of this enzyme are UDP-L-rhamnose and a flavonol 3-O-D-glucoside. Its products are uridine diphosphate (UDP) and the corresponding flavonol 3-O-[beta-L-rhamnosyl-(1->6)-beta-D-glucoside].
For example, the enzyme converts isoquercetin to rutin by adding an L-rhamnose sugar unit from UDP-L-rhamnose. It has been characterised from tulip and Arabidopsis thaliana.
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-L-rhamnose:flavonol-3-O-D-glucoside 6''-O-L-rhamnosyltransferase. Other names in common use include uridine diphosphorhamnose-flavonol 3-O-glucoside, rhamnosyltransferase, and UDP-rhamnose:flavonol 3-O-glucoside rhamnosyltransferase.
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