Identification, properties, and genetic control of UDP-glucose: cyanidin-3-rhamnosyl-(1 leads to 6)-glucoside-5-O-glucosyltransferase isolated from petals of the red campion (Silene dioica).
An enzyme catalyzing the transfer of the glucosyl moiety of UDP-glucose to the 5-hydroxyl group of cyanidin-3-rhamnosyl-(1 leads to 6)-glucoside has been demonstrated in petal extracts of Silene dioica plants. This glucosyltransferase activity was not detectable in green parts of these plants. The enzyme activity is controlled by a single dominant gene M; no glucosyltransferase activity could be demonstrated in petals of m/m plants. The enzyme was purified eightyfold by PVP and Sephadex G50 chromatography. The glucosyltransferase had a pH optimum of 7.4, had a molecular weight of about 55,000, was stimulated by divalent metal ions, and had a "true Km" values of 0.5 x 10(-3) M for UDP-glucose and 3.6 x 10(-3) M for cyanidin-3-rhamnosylglucoside. Pelargonidin-3-rhamnosylglucoside also could serve as acceptor. The enzyme did not catalyze the glucosylation of the 5-hydroxyl group of cyanidin-3-glucoside, although in petals of M/- n/n mutants cyanidin-3,5-diglucoside is present. ADP-glucose could not serve as a glucosyl donor.
D000872:Anthocyanins / Q000096:biosynthesis; D002850:Chromatography, Gel; D005799:Genes, Dominant; D005960:Glucosides / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics* / Q000302:isolation & purification; D008626:Mercuribenzoates / Q000494:pharmacology; D008970:Molecular Weight; D010944:Plants / Q000235:genetics*
D000872:Anthocyanins; D005960:Glucosides; D008626:Mercuribenzoates; D005964:Glucosyltransferases