Partial Purification and Some Properties of l-Sinapoylglucose: Choline Sinapoyltransferase (“Sinapine Synthase”) from Seeds of Raphanus sativus L. and Sinapis alba L

Hydroxycinnamoyltransferases which catalyze the formation of O-sinapoylcholine (sinapine) using l-0-sinapoyl-ß-D-glucose as acyl donor have been isolated from seeds of radish (Raphanus sativus L. var. sativus) and mustard (Sinapis alba L.) and purified 420and 293-fold, respectively. The enzymes (“sinapine synthase”) had apparent molecular weights of about 60,000 daltons and showed highest activities at pH 7.2 and 7.6, respectively, at 45 °C with apparent energies of activation at 53 kJ m ol-1. There were no requirements for divalent cations or sulfhydryl reagents. The apparent K m's of the radish and mustard enzymes were 0.48 and 0.71 m M for 1-sinapoylglucose and 5.3 and 6.5 mM for choline, respectively. The 1-feruloyland 1-p-coumaroylglucose were found to tard). 6-0-Sinapoylglucose, 3-0-sinapoylfructose, 1-0accepted as donors.