GALLOTANNIN BIOSYNTHESIS - PURIFICATION OF BETA-GLUCOGALLIN - 1,2,3,4,6-PENTAGALLOYL-BETA-D-GLUCOSE GALLOYLTRANSFERASE FROM SUMAC LEAVES

An enzyme from leaves of staghorn sumac (Rhus typhina) that catalysed the galloylation of 1,2,3,4, 6-penta-O-galloyl-beta-D-glucose to the g allotannin, -digalloyl-1,2,4,6-tetra-O-galloyl-beta-D-glucose, was pur ified more than 500-fold to apparent homogeneity. beta-Glucogallin (1- O-galloyl-beta-D-glucopyranose) served as activated acyl donor in this conversion. For the native enzyme, a M-r value of 170,000 was determi ned by gel filtration, while a single polypeptide band of M-r 42,000 w as detected by SDS-PAGE. The acyltransferase had pH and temperature op tima of 4-4.5 and 25 degrees, respectively, and was most stable betwee n pH 3 and 4.5. Besides the major substrate, pentagalloylglucose, also 1,2,3,6-tetragalloylglucose and hexa- to nona-substituted gallotannin s were accepted as minor substrates by this new enzyme for which the s ystematic name ''beta-glucogallin: 1,2,3,4,6-pentagalloyl-beta-D-gluco se (3-O-galloyl)-galloyltransferase'' (EC 2.3.1.-) is proposed. (C) 19 98 Elsevier Science Ltd. All rights reserved.