Purification and some properties of five anthraquinone specific glucosyltransferases from Cinchona succirubra cell suspension culture

Five anthraquinone-specific glucosyltransferases were partially purified from Cinchona succirubra cell suspension culture by fractional precipitation with ammonium sulphate, gel filtration and chromatofocusing on a fast protein liquid chromatography system. Five, distinct glucosylating activities were resolved with apparent pI values of 5.3, 4.8, 4.5, 4.3 and 4.1. They accepted emodin, anthrapurpurin, quinizarin, 2,6-dihydroxy anthraquinone and 1,8- dihydroxy anthraquinone as the best substrates, respectively. These enzymes exhibited similar characteristics as to pH optimum (pH 7) in histidine/HCl buffer, M, 50 000, had no cation requirement and were inhibited by various SH-group reagents. The K m value of the respective anthraquinones for either of the five enzymes was 10 μM. The physiological role of these novel enzymes is discussed in relation to the biosynthesis of anthraquinone glucosides in this tissue.