Asparagine-linked oligosaccharides were quantitatively released by hydrazinolysis from an alkaline phosphatase, Kasahara isozyme, which was purified from FL amnion cells. Almost all of the oligosaccharides (98%) were acidic components, all of which can be converted to neutral oligosaccharides upon sialidase digestion. Structural analysis of the oligosaccharides by sequential exoglycosidase digestion in combination with methylation analysis revealed that the alkaline phosphatase of FL cells contains sialylated mono-, bi-, tri-, and tetraantennary complex type sugar chains with the Galβ1→4GlcNAcβ1→ outer chains. Some of the tetraantennary sugar chains contain a single Galβ1→4GlcNAcβ1→3Galβ1→4GlcNAcβ1→ outer chain on their Manα1→6 arm. Both fucosylated and nonfucosylated trimannosyl cores were found in the sugar chains. However, it is of interest that the core portion of monoantennary oligosaccharide was not fucosylated and that of the tetraantennary oligosaccharide with a tetrasaccharide outer chain was completely fucosylated.

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This study was supported in part by a Grant-in-Aid for Special Project Research (Cancer-Bioscience) from the Ministry of Education, Science and Culture of Japan.

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