Sequencing analysis of the major minimal PTN-binding SS-CS/DS hexasaccharide fraction. The major fraction (M) of the minimal PTN-binding hexasaccharides, which was eluted at 69.8 min under supplemental Fig. S3, was analyzed. The disaccharide composition of fraction M was determined by comparing the elution positions of the 2-AB-labeled unsaturated disaccharides produced by CSases ABC (B) and B (C) with those of authentic 2-AB-derivatized unsaturated CS disaccharides indicated by arrows (A). 1, ΔO; 2, ΔC; 3, ΔA; 4, ΔD; 5, ΔB; 6, ΔE; and 7, ΔT (Δ4,5HexUA(2S)α1–3GalNAc(4S,6S)). For the abbreviations, ΔO, ΔA, ΔB, ΔC, ΔD, and ΔE, see Table 1 and Ref. 11. The sequencing analysis was achieved by digestion with various CSases, followed by anion exchange HPLC on an amine-bound silica PA-03 column using a NaH2PO4 gradient. Fraction M was labeled with 2-AB, and digested with CSase AC-II (D), ABC (E), or B (F), and each digest was analyzed by anion exchange HPLC. The CSase ABC digest was labeled with 2-AB again to determine the disaccharide located at the non-reducing end of the hexasaccharide.