Modification with galactose oxidase

Fetuin. — After introduction of aldehyde groups at C-7 of neuraminic acid residues in fetuin, an amine-containing spectroscopic probe has been attached to the molecule by reductive amination. The spin-label has also been introduced into asialofetuin after modification of the glycoprotein with either D-galactose oxidase or sodium periodate. 

Chemical modification e.g. periodate oxidation and then reduction) or loss of the terminal N-acetylneuraminic acid residues of human-plasma a,-antitrypsin did not destroy its ability to inhibit either trypsin or chymotrypsin neither did oxidation of the exposed D-galactopyranosyl residues in the desialylated glycoprotein with D-galactose oxidase. However, enzymic oxidation of the D-galactopyranosyl residues increased the survival time of the modified glycoprotein in plasma towards that exhibited by fully sialylated a -antitrypsin, whereas the desialylated glycoprotein was rapidly cleared following injection into rats. Contrary to previous evidence, there appears to be little or no difference between the carbohydrate compositions of the M and Z variants of human-plasma a,-antitrypsin. ... 

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