Methanolysis products of asparagine-linked N-acetylglucosamine and a new method for determination of N- and O-glycosidic N-acetylglucosamine in glycoproteins that contain asparagine-linked carbohydrates

✍ Scribed by Tomohiro Mega; Tokuji Ikenaka

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 630 KB
• Volume: 119
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(82)90659-5

✦ Synopsis

Amino acid analyzer and gas chromatographic analyses of methanolysates of model compounds of N-glycosidic and 0-glycosidic N-acetylglucosamine shows that the main product of N-glycosidic N-acetylglucosamine is glucosamine and that of 0-glycosidic N-acetylglucosamine is methyl a-glucosaminide. The amounts of N-acetylglucosamine in glycoproteins determined by methanolysis followed by gas-liquid chromatography represent the amount of 0glycosidic N-acetylglucosamine. A new method was developed to determine O-glycosidic and N-glycosidic N-acetylglucosamine in glycoproteins. Glucosamine and methyl a-glucosaminide in the methanolysates of glycoproteins are determined in an amino acid analyzer using the buffer system that is usually used for analysis of basic amino acids in the twocolumn system. The contents of O-and N-glycosidic N-acetylglucosamine of Taka-amylase A, ovalbumin, and egg white and yolk flavoproteins determined by the method agree reasonably well with the values calculated from the carbohydrate structures or compositions of the compounds. Therefore, this method can be used to determine the number of N-glycosidically linked carbohydrate chains together with the amount of O-glycosidic N-acetylglucosamine in glycoproteins.