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Glycoproteins and Proteoglycans. Proteins conjugated to saccharides lacking a serial repeat unit. Glycoproteins. Protein >> carbohydrate. Proteins conjugated to polysaccharides with serial repeat units. Proteoglycans. Carbohydrate >> protein. Glycosaminoglycans Mucopolysaccharides.
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Glycoproteins and Proteoglycans Proteins conjugated to saccharides lacking a serial repeat unit Glycoproteins Protein >> carbohydrate Proteins conjugated to polysaccharides with serial repeat units Proteoglycans Carbohydrate >> protein Glycosaminoglycans Mucopolysaccharides Repeat unit HexN and HexUA
Glycopeptide bonds Asn Glc NAc Type I N-Glycosyl linkage to Asn Ser HOLys Glc Glc NAc Type II O-Glycosyl linkage to Ser (Thr) Type III O-Glycosyl linkage to 5-HOLys
β-1,3 β-1,4 Glycosaminoglycans GlcUA GlcNAc No protein link No sulfate β-1,3 glycosidic linkage Hyaluronate
β-1,3 β-1,4 Glycosaminoglycans GlcUA GalNAc GlcUA-Gal-Gal-Xyl-O-Ser link Sulfate at 4 or 6 C of GalNAc β-1,3 glycosidic linkage Chondroitin sulfate
β-1,3 β-1,4 Glycosaminoglycans IdUA GalNAc IdUA with some GlcUA Sulfate at 4 or 6 C of GalNAc β-1,3 glycosidic linkage Dermatan sulfate
α-1,4 α-1,4 Glycosaminoglycans GlcUA GlcNAc GlcN and GlcUA or IdUA N and O sulfate (C2,3,6) α-1,4 glycosidic linkage Heparin > NAc < N and O sulfate Heparan sulfate
β-1,4 β-1,3 Glycosaminoglycans GlcUA GlcNAc GlcNAc and Gal (no UA) Sulfate on C6 of Gal or HexN β-1,4 glycosidic linkage Keratan sulfate I Keratan sulfate II GalNAc-O-Ser or Thr