Purification of limonoid glucosyltransferase from navel orange albedo tissues

Abstract UDP- d -glucose: limonoid glucosyltransferase was purified from albedo tissues of navel orange ( Citrus sinensis ) cultivars, Frost and Newhall, by a combination of (NH 4 ) 2 SO 4 fractionation, UDP-glucuronic acid affinity chromatography and DEAE ion exchange HPLC. This procedure resulted in a 452-fold increase in enzyme purification. This enzyme catalysed 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 between pH 6.5 and 9.0 with an optimum at 8.0. Mn 2+ stimulated enzyme activity by 66% over basal activity observed with EDTA. Activity was lost when the purified enzyme was frozen and stored in Tris-HCl buffer at pH 8.0. Published by Elsevier Science Ltd