Heparin proteoglycans synthesized by mouse mastocytoma contain chondroitin sulphate.
Proteoglycans (PGs), biosynthetically labelled with [35S]sulphate, were isolated from mouse mastocytoma tissue. Chromatography on antithrombin (AT)-Sepharose resulted in the separation of the 35S-labelled PGs into three fractions: PGs with no affinity for the gel (NA-PGs), PGs with low affinity (LA-PGs), and PGs with high affinity (HA-PGs) for antithrombin. Whereas NA-PGs contained almost exclusively chondroitin sulphate (CS), the AT-binding PGs contained 80-85% heparin and 15-20% CS. [35S]CS-containing macromolecules obtained from the HA-PG fraction after removal of the heparin polysaccharide chains were rechromatographed on AT-Sepharose. A majority of these 35S-labelled macromolecules no longer showed affinity for AT. These experiments indicate that the [35S]CS recovered in the AT-binding PGs is present in hybrid PGs. Polysaccharide chain-length determination demonstrated that the heparin chains were somewhat larger (M(r) approximately 30,000) than the CS chains in the NA-PGs (M(r) approximately 25,000). CS chains in the hybrid PGs were slightly smaller (M(r) approximately 20,000). Characterization of the sulphated CS disaccharides from NA- and HA-PGs showed that they contained similar amounts (20%) of disulphated disaccharides of [GlcA-GalNAc(4,6-di-OSO3)] type. The monosulphated CS-disaccharides were O-sulphated at C-4 of the galactosamine units. Analysis by gel chromatography of the [35S]CS components isolated from HA-PGs after heparinase treatment showed that a major portion of these contained one CS chain only. Calculations of the number of CS and heparin chains in AT-binding PGs, based on polysaccharide composition and polysaccharide chain length, indicate that all heparin-containing PGs are hybrids.
Lidholt
K
K
Department of Medical and Physiological Chemistry, University of Uppsala, Sweden.
Eriksson
I
I
Kjellén
L
L
D000818:Animals; D002240:Carbohydrate Sequence; D002809:Chondroitin Sulfates / Q000032:analysis*; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D004187:Disaccharides / Q000032:analysis; D006493:Heparin / Q000031:analogs & derivatives* / Q000032:analysis / Q000096:biosynthesis; D006863:Hydrogen-Ion Concentration; D012515:Mast-Cell Sarcoma / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011509:Proteoglycans / Q000032:analysis / Q000096:biosynthesis*; D013431:Sulfates / Q000378:metabolism; D013462:Sulfur Radioisotopes
D004187:Disaccharides; D011509:Proteoglycans; D013431:Sulfates; D013462:Sulfur Radioisotopes; C036090:heparin proteoglycan; D006493:Heparin; D002809:Chondroitin Sulfates