PURIFICATION OF LIMONOID GLUCOSYLTRANSFERASE FROM NAVEL ORANGE ALBEDOTISSUES

UDP-D-glucose:limonoid glucosyltransferase was purified from albedo ti ssues of navel orange (Citrus sinensis) cultivars, Frost and Newhall, by a combination of (NH4)(2)SO4 fractionation, UDP-glucuronic acid aff inity chromatography and DEAE ion exchange HPLC. This procedure result ed in a 452-fold increase in enzyme purification. This enzyme catalyse d the glucosylation of both nomilin and limonin. SDS-PAGE showed a M-r of 56-58 k for the enzyme. The enzyme displayed a peak of activity be tween pH 6.5 and 9.0 with an optimum at 8.0. Mn2+ stimulated enzyme ac tivity by 66% over basal activity observed with EDTA. Activity was los t when the purified enzyme was frozen and stored in Tris-HCl buffer at pH 8.0. Published by Elsevier Science Ltd.