Sinapine esterase that catalyzes that hydrolysis of sinapine, releasing choline and sinapate. Sinapine (O-sinapoylcholine) is the predominant phenolic compound in a complex group of sinapate esters in seeds of oilseed rape (B.napus). Sinapine has antinutritive activity and prevents the use of seed protein for food and feed. Shows broad substrate specificity towards various other choline esters, including phosphatidylcholine. H2O + O-sinapoylcholine = choline + E-sinapate + H(+) Inhibited by PMSF. Expressed in most tissues or organs of the mature seedlings. Not expressed in roots of mature seedlings. Expressed during reproductive growth and strongly expressed during seed germination. Expression is not detected until 3 days after germination, and subsequently becomes stronger. Not present in root of seedlings growing at different stages. Overexpression in seeds induces a strong decrease of sinapine levels together with an increase of choline. Seeds display higher weight, size and water content and a fraction of seeds display morphological alterations, characterized by large cavities near the embryonic tissue. Seed quality parameters, such as fiber and glucosinolate levels, and agronomically important traits, such as oil and protein contents, differ only slightly, except that amounts of hemicellulose and cellulose are higher. Seedlings are larger and young seedlings exhibit longer hypocotyls. Metabolic profiles of transgenic seeds indicate that, besides suppression of sinapine accumulation, other differences in primary and secondary metabolism are observed. Belongs to the 'GDSL' lipolytic enzyme family.