Analysis of oligosaccharide structures from the reducing end terminal by combining partial acid hydrolysis and a two-dimensional sugar map.

A new sensitive and convenient method for the structural analysis of oligosaccharides was developed, in which partial acid hydrolysis was combined with two-dimensional sugar mapping of pyridylamino (PA)-oligosaccharides. A PA-oligosaccharide was partially hydrolyzed, the acid hydrolysis conditions being optimized so as to obtain various PA-oligosaccharide fragments with high yields from different types of PA-oligosaccharides. The acid hydrolyzates were then fractionated every 1 glucose unit by size-fractionation HPLC, and each fraction was analyzed by reversed-phase HPLC. The structure of each PA-oligosaccharide fragment was identified on a two-dimensional sugar map prepared with standard PA-sugar chains, after which the original PA-oligosaccharide was reconstructed from the reducing end terminal based on the obtained structures of the PA-oligosaccharide fragments. The method was successfully applied to resolving the structure of an N-linked sugar chain.