N-acetylneuraminic acid residues

In the trisialoglycolipid from D. nipon hepatopancreas, some of the N-acetylneuraminic acid residues are in the form of the 8-O-methyl derivative, whose structure was proved by mass spectrometry.192... 

The more-polar sialoglycolipid is a disialoglycolipid having a linear octasac-charide chain. Both N-acetylneuraminic acid residues are situated inside the chain and glycosylated at 0-4 by galactosyl residues.207... 

The N-acetylneuraminic acid residue situated closer to the nonreducing end of the chain is present in the form of its 8-O-methyl derivative. 

Influence of oe-(2— 3)-linked and -(2— 6)-linked, Terminal N-Acetylneuraminic Acid Residues on the Chemical Shift of Anomeric and N-Acetyl Protons of Other Monosaccharide Residues Present in a Dianteunary Clycari 4 1 ... 

The surfaces of human RBCs are negatively charged, mainly owing to the carboxyl group of the N-acetylneuraminic acid residue of the... 

The Four Different, N-Acetylneuraminic Acid Residues in the Native Polysaccharide Antigen of Group C Neisseria meningitidis. 

The first enzymatic step involves the covalent attachment of the first carbohydrate unit to the side chain of a specific amino acid residue. Further sugar residues are added in sequential order by specific glycosyltransferases for each of the sugar residues. It appears that specific multienzyme systems are required for the biosynthesis of each type of polymer (153). Frequently the carbohydrate chain terminates with an N-acetylneuraminic acid residue. 

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. ... 

In the other two oligosaccharide units, one of the two N-acetylneuraminic acid residues is lacking in each case. 

---