Glycosaminoglycans (GAGs) or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit. Textbook: Proteoglycans and Sulfated Glycosaminoglycans
Disaccharide Units of GAGs.
glycosaminoglycans
Heparin/HS and hyaluronic acid (HA) are ;
galactosaminoglycans
chondroitin-4-sulfate (C4S), chondroitin-6-sulfate (C6S) and dermatan sulfate (DS)
sulfated polylactosamine
keratan sulfate (KS)
Since heparin/HS structures are highly heterogeneous, only their most abundant disaccharide unit IdoA-GlcNSO3 is shown here.
{| class="wikitable"
| '''Name''' || '''Hexuronic acid / Hexose''' || '''Hexosamine''' || '''Linkage geometry between predominant monomeric units''' || '''Unique features'''
|-
|-valign="top"
| [[Chondroitin sulfate]] || GlcUA or GlcUA || GalNAc or GalNAc(4S) or GalNAc(6S) or GalNAc(4S,6S) || '''4'''GlcUA'''''β''1-3'''GalNAc'''''β''1''' || Most prevalent GAG
|-
|-valign="top"
| [[Dermatan sulfate]] || GlcUA or IdoUA or IdoUA || GalNAc or GalNAc(4S) or GalNAc(6S) or GalNAc(4S,6S) || '''4'''IdoUA'''''β''1-3'''GalNAc'''''β''1''' || Distinguished from chondroitin sulfate by the presence of [[iduronic acid]], although some hexuronic acid monosaccharides may be [[glucuronic acid]].[{{cite journal | author=Trowbridge JM, Gallo RL. | title=Dermatan sulfate: new functions from an old glycosaminoglycan | journal=Glycobiology | year=2002 | pages=117R–125R | volume=12 | issue=9 | pmid=12213784 | doi=10.1093/glycob/cwf066}}]
|-
|-valign="top"
| [[Keratan sulfate]] || Gal or Gal(6S) || GlcNAc or GlcNAc(6S) || '''3'''Gal(6S)'''''β''1-4'''GlcNAc(6S)'''''β''1''' || Keratan sulfate type II may be [[fucose|fucosylated]].[{{cite journal | author = Funderburgh JL. | title = Keratan sulfate: structure, biosynthesis, and function | journal = Glycobiology | year=2000 | volume=10 | issue =10 | pages=951–958 | pmid = 11030741 | doi = 10.1093/glycob/10.10.951}}]
|-
|-valign="top"
| [[Heparin]] || GlcUA or IdoUA || GlcNAc or GlcNS or GlcNAc(6S) or GlcNS || '''4'''IdoUA'''''α''1-4'''GlcNS'''''α''1''' || Highest negative charge density of any known biological molecule
|-
|-valign="top"
| [[Heparan sulfate]] || GlcUA or IdoUA or IdoUA || GlcNAc or GlcNS or GlcNAc(6S) or GlcNS || '''4'''GlcUA'''''β''1-4'''GlcNAc'''''α''1''' || Highly similar in structure to heparin, however heparan sulfates disaccharide units are organised into distinct sulfated and non-sulfated domains.[{{cite book | title=Proteoglycans: structure, biology and molecular interactions | author=Gallagher, J.T., Lyon, M. | chapter=Molecular structure of Heparan Sulfate and interactions with growth factors and morphogens | editor=Iozzo, M, V. | year=2000 | publisher=Marcel Dekker Inc. New York, New York | pages=27–59}}]
|-
|-valign="top"
| [[Hyaluronan]] || GlcUA || GlcNAc || '''4'''GlcUA'''''β''1-3'''GlcNAc'''''β''1''' || The only GAG that is exclusively non-sulfated
|}
