FIGURE 1.

Aniline-tagging of GAG disaccharides. A, the reducing form of each GAG disaccharide can form a Schiff base with the amine group of aniline. The resulting imine is then reduced with sodium cyanoborohydride resulting in a stable derivative. B, to determine the sensitivity and linear range of GRIL disaccharide analysis, D2S0 was labeled with either [¹²C₆]aniline or [¹³C₆]aniline. Differing amounts of [¹²C₆]aniline-labeled D2S0 (between 0.5 pmol and 1 nmol) were mixed in triplicate with 25 pmol of [¹³C₆]aniline-labeled D2S0 prior to LC/MS analysis. The measured amount (y-axis) is plotted against the amount of [¹²C₆]aniline-labeled disaccharide added (x-axis). The standard error was less than the diameter of the symbols and <5%.