Sinapoylglucose: malate sinapoyltransferase activity in seeds and seedlings of rape.

Protein preparations from seeds and seedlings (cotyledons) of rape (Brassica napus subsp. napus [L.] DC.) catalyzed the transfer of sinapic acid from 1-Osinapoyl-β-glucose to malate in the formation of O-s-inapoylmalate. The enzyme involved, 1-O-sinapoyl-β-glucose: L-malate O-sinapoyltransferase (SMT; EC 2.3.1), catalyzes the key step in the overall conversion of the seed constituent sinapine (O-sinapoylcholine) to the accumulating O-sinapoylmalate by way of the intermediate 1-O-sinapoyl-β-glucose. The present paper describes this phenomenon focussing on SMT activity.