Fig. 3.

Structures of the substrates for 3-O-sulfotransferases. (A) The heptasaccharide substrate used for 3-OST-1 crystallization and mutational analysis. (B) The tetrasaccharide used for the crystallization of the ternary complex of 3-OST-3/PAP/tetrasaccharide (9). (C) The octasaccharide substrate used for analyzing 3-OST-3 wild-type and mutant proteins described in this study. The tetrasaccharide and the octasaccharide were purified from heparin lyase-degraded heparin (15), whereas the heptasaccharide was enzymatically synthesized (8). The 3-O-sulfation site in each substrate is indicated by an arrow. The identical trisaccharide regions between the heptasaccharide and tetrasaccharide are depicted in a dashed box. All substrates are shown with the nonreducing end on the left and the reducing end on the right.