In enzymology, a sinapoylglucose---choline O-sinapoyltransferase (EC 2.3.1.91) is an enzyme that catalyzes the chemical reaction

1-O-sinapoyl-beta-D-glucose + choline ${\displaystyle \rightleftharpoons }$ D-glucose + sinapoylcholine

Thus, the two substrates of this enzyme are 1-O-sinapoyl-beta-D-glucose and choline, whereas its two products are D-glucose and sinapoylcholine (sinapine).

This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is 1-O-(4-hydroxy-3,5-dimethoxycinnamoyl)-beta-D-glucose:choline 1-O-(4-hydroxy-3,5-dimethoxycinnamoyl)transferase. This enzyme is also called sinapine synthase. This enzyme participates in phenylpropanoid biosynthesis.