Ellagitannin biosynthesis: laccase-catalyzed dimerization of tellimagrandin II to cornusiin E in Tellima grandiflora.
An enzyme has been purified from leaves of the weed Tellima grandiflora (fringe cups, Saxifragaceae) that catalyzed the O2-dependent oxidation of the monomeric ellagitannin, tellimagrandin II, to a dimeric derivative, cornusiin E. The apparently homogeneous enzyme preparation had a Mr of ca. 160,000 (with four subunits of Mr 40,000), a pH-optimum and an isoelectric point at pH 5.2, and was most stable at pH 4.3. Inhibition studies revealed that this new enzyme, for which the systematic name 'tellimagrandin II: O2 oxidoreductase' is proposed, is a member of the laccase (EC 1.10.3.2) family of phenol oxidases. The properties of this enzyme differed from that of a related laccase that catalyzed the transition of 1,2,3,4,6-pentagalloylglucopyranose to tellimagrandin II, the preceding step in the biosynthetic route to cornusin E.
Niemetz
Ruth
R
Molekulare Botanik, Universität Ulm, D-89069 Ulm, Germany.
Gross
Georg G
GG
D002384:Catalysis; D019281:Dimerization; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D005960:Glucosides / Q000737:chemistry / Q000378:metabolism*; D047348:Hydrolyzable Tannins / Q000031:analogs & derivatives* / Q000378:metabolism; D042845:Laccase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D018515:Plant Leaves / Q000378:metabolism; D031995:Saxifragaceae / Q000201:enzymology / Q000378:metabolism*; D013634:Tannins / Q000096:biosynthesis* / Q000378:metabolism*
D004791:Enzyme Inhibitors; D005960:Glucosides; D047348:Hydrolyzable Tannins; D013634:Tannins; C480119:cornusiin E; C013515:ellagitannin; C473299:tellimagrandin II; C435084:pentagalloylglucose; D005707:Gallic Acid; D042845:Laccase