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Partial Purification and Some Properties of a Hydroxycinnamoyl Glucosyltransferase from Tomato Fruits

Fleuriet, A., Macheix, J. J., Suen, R., Ibrahim, R. K.
Zeitschrift für Naturforschung 2014 v.35 no.11-12 pp. 967-972
EDTA (chelating agent), ammonium sulfate, cherries, chromatography, divalent metals, esters, ferulic acid, fruits, glucose, glucose 1-phosphate, glucosides, metal ions, pH, tomatoes, uridine diphosphate
A glucosyltransferase was isolated from immature “cherry” tomatoes and was partially purified (200-fold) by ammonium sulphate precipitation and successive chromatography on Sephadex G-100 and DEAE-cellulose columns. The enzyme utilised the free hydroxycinnamic acids and UDP-glucose in the formation of their respective glucosides (pH 8.0) and glucose esters (pH 7.0); but did not accept the CoA thiolesters of HCAs in the presence of glucose-1-phosphate. The constant glucoside/glucose ester ratio observed during purification suggests that both reactions are catalysed by the same enzyme. The Kₘ values for ρ-coumaric, caffeic, ferulic and sinapic acids were 0.8, 1.5, 1.4 and 2.5 μᴍ, respectively. With ferulic acid as substrate, the Kₘ value for UDPG was 10 μᴍ. The enzyme required an -SH group for activity and the reaction was strongly inhibited by EDTA, divalent metal ions and UDP.