Purification and properties of UDP-glucose: Coniferyl alcohol glucosyltransferase from suspension cultures of Paul's scarlet rose

Abstract

UDP-glucose:coniferyl alcohol glucosyltransferase was isolated from 10-day-old, darkgrown cell suspension cultures of Paul's scarlet rose. The enzyme was purified 120-fold by (NH 4) 2SO 4 fractionation and chromatography on DEAE-cellulose, hydroxyapatite, and Sephadex G-100. The enzyme has a pH optimum of 7.5 in Tris-HCl buffer, required an -SH group for activity, and is inhibited by ϱ-chloromercuribenzoate and EDTA. Its molecular weight is estimated to be 52,000. The enzyme is specific for the glucosylation of coniferyl alcohol ( K m 3.3 × 10 −6 M) and sinapyl alcohol ( K m 5.6 × 10 −6 M). With coniferyl alcohol as substrate the apparent K m value for UDP-glucose is 2 × 10 −6 m. The enzyme activity can be detected in a number of callus-tissue and cell-suspension cultures. The role of this enzyme is believed to be to catalyze the transfer of glucose from UDPG to coniferyl (or sinapyl) alcohol as storage intermediates in lignin biosynthesis.