Epigallocatechin gallate 7-O-alpha-D-glucopyranoside (EGCG-G1), as a novel compound with a higher water solubility and stability and similar antioxidant effect when compared with epigallocatechin gallate (EGCG), was produced from sucrose as a glucose donor and EGCG as a glucose acceptor by a glucosyltransferase from Leuconostoc mesenteroides. The pH and temperature for maximum EGCG-G1 production by the glucosyltransferase were 5.0 and 25 degrees C, respectively. The enzyme and substrates concentrations to produce maximum EGCG-G1 were 3.78 units/mL, 25 mM sucrose, and 1.5 mM EGCG, respectively. Under these conditions, the glucosyltransferase produced 1.0 mM EGCG-G1 from 1.5 mM EGCG at a reaction time of 180 min, corresponding to formation of 67% product on a mole basis.