Synthesis of PEG40-GSnP-6 (P-G6). P-selectin antagonist GSnP-6 is modeled after the N terminus of human PSGL-1, including sialyl Lewis^X (N-acetylneuraminic acid)–containing hexasaccharide and sulfopeptide epitopes responsible for high-affinity binding to P-selectin. A linear 40-kDa mPEG-SVA was conjugated to the ε-amino residue of the N terminal lysine of GSnP-6 affording P-G6. The glycan short form (A) and full chemical structure (B) of P-G6 are shown.