Alternative definition : KEGG: Keratan sulfate (KS) is a glycosaminoglycan with the basic disaccharide unit
of N-acetyllactosamine, Gal(b1-4)GlcNAc(b1-3), with sulfate esters at C-6 of GlcNAc
and Gal residues. There are two types of KS distinguished by the protein linkage:
type I for N-linked via the N-glycan core structure and type II for O-linked via the
O-glycan core 2 structure.;