Abnormal urinary excretion of sialoglycoconjugates in patients with mucolipidosis.
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Low molecular sialoglycoconjugates were isolated by the charcoal adsorption method from the urines of patients with mucolipidosis (one patient with mucolipidosis type I variant and three patients with mucolipidosis type II). The sialoglycoconjugates were fractionated into two major fractions (SG-1 and SG-2) by Sephadex G-25 gel filtration, and a strikingly increased excretion of the SG-1 fraction was observed in patients with these diseases. The SG-1 fraction from each type of mucolipidosis was fractionated into four subfractions by Sephadex G-50 gel filtration, and the fraction with the lowest molecular weight (SG-1-III) was found to contribute to the increase in the levels of SG-1. The SG-1-III fraction was further fractionated into 7 to 8 subfractions by ion-exchange chromatography. The comparison of the amounts and the chemical compositions of the subfractions suggested that the increase in SG-1 was dependent upon the increase in excretion of mannose-containing sialooligosaccharides with the structures closely related to the carbohydrate units of glycoproteins with an N-glycosidic linkage.