Purification and characterization of gentisic acid glucosyltransferase from the cultured cells of Catharanthus roseus

A 41 kDa glucosyltransferase was isolated from the cultured cells of Catharanthus roseus. The enzyme specifically catalyzed the monoglucosylation of phenolic compounds, such as hydroxybenzoic acid and hydroxycoumarins. The enzyme activity was optimal at pH 8.0 and 37 °C and was strongly inhibited by divalent cations, such as Mn2+, Co2+, Zn2+ and Fe2+. Gentisic acid was the best substrate with a Km value of 9 μM. The enzyme glucosylates regioselectively 5-hydroxyl group of 2,5-dihydroxybenzoic acid (gentisic acid) by the transfer of glucose from UDP-glucose (UDPG).