Linamarin synthase () is an enzyme that catalyzes the chemical reaction

The two substrates of this enzyme characterised from flax (Linum usitatissimum) are acetone cyanohydrin and UDP-glucose. Its products are linamarin and uridine diphosphate (UDP).

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-glucose:2-hydroxy-2-methylpropanenitrile beta-D-glucosyltransferase. Other names in common use include uridine diphosphoglucose-ketone glucosyltransferase, uridine diphosphate-glucose-ketone cyanohydrin, beta-glucosyltransferase, UDP glucose ketone cyanohydrin glucosyltransferase, UDP-glucose:ketone cyanohydrin beta-glucosyltransferase, and uridine diphosphoglucose-ketone cyanohydrin glucosyltransferase.

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