Characterization of the Subunits and Sugar Moiety of Human Placental and Leukemicβ-Glucuronidase

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Abstract
Beta-Glucuronidase purified from human placenta and chronic myelogenous leukemic cells was composed of three components of 18, 64 and 80 kDa, though the relative contents of the components were different between the sources. Analysis of their N-terminal amino-acid sequences showed that the 18-kDa and 64-kDa components were derived from the 80-kDa component by cleavage between Val159 and Gly160. Furthermore, the enzyme was found to be glycosylated at Asn173 and Asn420 with high mannose-type oligosaccharides, based on the electrophoretic mobility of the components as well as the endopeptidic peptides before and after endoglycosidase treatment. The enzyme purified from leukemic cells was poorly phosphorylated by N-acetylglucosamine 1-phosphotransferase as compared to the placental enzyme.