Figure 2. Structure of low-pH nitrous acid digestion-generated oligosaccharides.

A nitrous acid digestion-generated oligosaccharide can be considered as a combination of one HexA-aMan_R, numbers of internal GlcA-GlcNAc and GlcA-GlcNH₂ and sulphates. p, number of internal disaccharides; q, number of sulphates; n, number of free amino groups; z, number of negative charges on the molecule. The linkage between the non-reducing end uronic acid and the next glucosamine residue is not specified since the uronic acid could be either GlcA or IdoA.