Isolation and structural characterization of sialic acid-containing glycopeptides of the O-GlycosidicType from the urine of two patients with an hereditary deliciency in α-N-acetylgalactosaminidase activity

Glycopeptides have been isolated fromthe urine of two patients, aged 5 and 6, with a newlysosomal storage disease characterized by a defi-ciency in α-Ν-acetylgalactosaminidase activity. Isola-tion of these glycopeptides was achieved using gel fil-tration and ion-exchange chromatography. Structuraldetermination was done using one- and two-dimen-sional 500 MHz 1H-NMR spectroscopy and FAB mass spectrometry of native and derivatized glyco-peptides. The following structures were inferred asbeing present: Glycopeptide A (up to 140 mg/l urine)(l)-(3)Neu5Acα2-3Galβ1-3(Neu5Acα2-6)GalNAcα1l- RAl:R = Ser A2:R=Thr A3:R=Thr-ProGlycopeptide Β (up to 80 mg/l urine)(4)-(6)Neu5Acα2-3Galβ1-4GlcNAcβ1-6(Neu5Acα2-3--Galβ1-3)GalNAcα1-R Bl:R = Ser B2:R=Thr B3: R =Thr-Pr