title: Gallotannin biosynthesis: beta-glucogallin: hexagalloyl 3-O-galloyltransferase from Rhus typhina leaves.
abstract: Leaves of staghorn sumac (Rhus typhina) contain several galloyltransferases that catalyze the beta-glucogallin dependent transformation of 1,2,3,4,6-pentagalloylglucose to gallotannins. Among these, an enzyme has been isolated that preferentially acylates the 3-position of the hexagalloylglucose, 3-O-digalloyl-1,2,3,4,6-tetra-O-galloylglucose, to afford the corresponding heptagalloylglucose being characterized by a 3-O-meta-trigalloyl side-chain. The enzyme, for which a M(r) of ca. 260,000 was determined, was purified to apparent homogeneity. SDS-PAGE suggested an alpha4beta4-conformation of the native enzyme. It had a pH-optimum and an isolelectric point at pH 5.6, was most stable at pH 4.0-4.3, and displayed excellent heat-stability and in particular an extreme cold-tolerance. We propose the systematic name "beta-glucogallin: hexagalloylglucose 3-O-galloyltransferase" for this new enzyme.
authors.affiliation: Molekulare Botanik, Universität Ulm, D-89069, Ulm, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Niemetz
authors.forename: G G
authors.initials: GG
authors.lastname: Gross
mesh_terms: D000215:Acylation; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D005960:Glucosides / Q000378:metabolism; D016695:Glycosyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D047348:Hydrolyzable Tannins / Q000378:metabolism*; D018515:Plant Leaves / Q000201:enzymology; D029045:Rhus / Q000201:enzymology*; D013379:Substrate Specificity / Q000502:physiology; D013634:Tannins / Q000378:metabolism*
chemical_list: C409902:3-O-digalloyl-1,2,4,6-tetra-O-galloylglucose; D005960:Glucosides; D047348:Hydrolyzable Tannins; D013634:Tannins; C435084:pentagalloylglucose; C060474:glucogallin; D005707:Gallic Acid; D016695:Glycosyltransferases; C448024:3-O-galloyltransferase