Increase of chondroitin 4-sulfate concentration in the endochondral ossification cartilage of normal dogs.

The absolute concentrations of chondroitin 4- and 6-sulfate are compared in articular and endochondral ossification cartilage from normal dogs. In newborn dogs, the absolute concentration of chondroitin 4-sulfate decreases nearly 3-fold from the deeper endochondral ossification cartilage to the articular surface, whereas that of chondroitin 6-sulfate does not change. In cartilage from the articular surface of the epiphysis in adults, where the ossification process is complete, the concentration of chondroitin 4-sulfate is also low. These observations suggest that chondroitin 4-sulfate may be important in the ossification process. The pathogenesis of heritable disorders involving the sulfation of chondroitin sulfate is discussed in view of these findings.

Occurrence of a unique fucose-branched chondroitin sulfate in the body wall of a sea cucumber.

The sulfated polysaccharides in the body wall of the sea cucumber occur as three fractions that differ markedly in molecular mass and chemical composition. The fraction containing a high molecular mass component has a high proportion of fucose and small amounts of galactose and amino sugars, whereas another fraction contains primarily a sulfated fucan. The third fraction (F-2), which represents the major portion of the sea cucumber-sulfated polysaccharides, contains approximately equimolar quantities of glucuronic acid, N-acetyl galactosamine, and fucose, and has a sulfate content higher than that in the other two fractions. The structure of fraction F-2 was examined in detail. This polysaccharide has an unusual structure composed of a chondroitin sulfate-like core, containing side chain disaccharide units of sulfated fucopyranosyl linked to approximately half of the glucuronic acid moieties through the O-3 position of the acid. These unusual fucose branches obstruct the access of chondroitinases to the chondroitin sulfate core of F-2. However, after partial acid hydrolysis, which removes the sulfated fucose residues from the polymer, fraction F-2 is degraded by chondroitinases into 6-sulfated and nonsulfated disaccharides.

Interaction of high molecular weight chondroitin sulfate from human aorta with plasma low density lipoproteins.

Aortic glycosaminoglycans were separated into fractions of increasing molecular weights containing heparan sulfate or chondroitin 4/6-sulfate + dermatan sulfate. When these fractions were added to plasma low density lipoproteins (LDL) in the presence of Ca2+, only chondroitin 4/6 sulfate + dermatan sulfate of high relative molecular weight produced turbidity. Treatment with testicular hyaluronidase abolished totally the formation of insoluble complex. When these glycosaminoglycans were applied to LDL-affinity columns in the presence of Ca2+, higher NaCl concentrations were necessary for the elution of the high relative molecular weight chondroitin sulfate. Heparan sulfate fractions did not produce turbidity when added to LDL solutions and were eluted from LDL-affinity columns at low NaCl concentrations. All these results suggest that besides the structure (or charge density), the molecular weight of the chondroitin sulfate chains is a relevant factor for the binding of this compound to LDL.

Distribution of chondroitin 4-sulfate and chondroitin 6-sulfate in human articular and growth cartilage.

The relative concentrations of chondroitin 4- and chondroitin 6-sulfate in different normal human cartilages are reported. Articular cartilages contained higher concentrations of chondroitin 6-sulfate, whereas growth cartilages contained nearly equal amounts of chondroitin 4- and chondroitin 6-sulfate. Adult cartilages, in which the calcification process is already complete, contained only chondroitin 6-sulfate. The results suggest that chondroitin 6-sulfate is related to the integrity of the articular surfaces, whereas chondroitin 4-sulfate seems to be an important factor in the calcification process. The pathogenesis of the bone and cartilage alterations that occur in patients affected by heritable disorders of the sulfation of chondroitin sulfate are discussed in view of these findings.

Intestinal mucosal mast cells from rats infected with Nippostrongylus brasiliensis contain protease-resistant chondroitin sulfate di-B proteoglycans.

Rats infected with the helminth Nippostrongylus brasiliensis were injected i.p. with 2 mCi of [35S] sulfate on days 13, 15, 17, and 19 after infection. The intestines were removed from animals on day 20 or 21 after infection, the intestinal cells were obtained by collagenase treatment and mechanical dispersion of the tissue, and the 35S-labeled mucosal mast cells (MMC) were enriched to 60 to 65% purity by Percoll centrifugation. The cell-associated 35S-labeled proteoglycans were extracted from the MMC-enriched cell preparation by the addition of detergent and 4 M guanidine HCl and were partially purified by density gradient centrifugation. The isolated proteoglycans were of approximately 150,000 m.w., were resistant to pronase degradation, and contained highly sulfated chondroitin sulfate side chains. Analysis by high-performance liquid chromatography of chondroitinase ABC-treated 35S-labeled proteoglycans from these rat MMC revealed that the chondroitin sulfate chains consisted predominantly of disaccharides with the disulfated di-B structure (IdUA-2SO4----GalNAc-4SO4) and disaccharides with the monosulfated A structure (G1cUA----GalNAc-4SO4). The ratio of disaccharides of the di-B to A structure ranged from 0.4 to 1.6 in three experiments. Small amounts of chondroitin sulfate E disaccharides (GlcUA----GalNAc-4,6-diSO4) were also detected in the chondroitinase ABC digests of the purified rat MMC proteoglycans, but no nitrous acid-susceptible heparin/heparan sulfate glycosaminoglycans were detected. The presence in normal mammalian cells of chondroitin sulfate proteoglycans that contain such a high percentage of the unusual disulfated di-B disaccharide has not been previously reported. The rat intestinal MMC proteoglycans are the first chondroitin sulfate proteoglycans that have been isolated from an enriched population of normal mast cells. They are homologous to the chondroitin sulfate-rich proteoglycans of the transformed rat basophilic leukemia-1 cell and the cultured interleukin 3-dependent mouse bone marrow-derived mast cell, in that these chondroitin sulfate proteoglycans as well as rat serosal mast cell heparin proteoglycans are all highly sulfated, protease-resistant proteoglycans.

Proteoglycans and chondroitin sulfates from human multiple chondroma (enchondromatosis).

1. This paper reports the structural analysis of proteoglycans and mucopolysaccharides extracted from a human multiple enchondroma (enchondromatosis), a benign cartilage tumor, where growth, but no calcification takes place. The tumors were located inside the phalanges of both hands of a 22-year-old patient and were obtained after surgery. 2. The proteoglycans of chondromas contain only a small amount of keratan sulfate (1.3% of total mucopolysaccharide) and the chondroitin sulfate is composed of 4- and 6-sulfated disaccharide units in approximately equivalent amounts, forming hybrid polymeric chains. Furthermore, the electrophoretic mobility of these proteoglycans in agarose-polyacrylamide large-pore gel indicates that they may occur as a single polydisperse component. This structural pattern is very similar to that of the proteoglycans present in the articular cartilage of normal human newborn and young. In contrast, the proteoglycans of adult articular cartilage contain higher amounts of keratan sulfate (25% of the total mucopolysaccharide) and very small amounts of 4-sulfated disaccharide units (7%) in the chondroitin sulfate molecules. The multiple zones observed in agarose/polyacrylamide large-pore gel electrophoresis indicate the presence of more than one polydisperse component. These findings suggest a correlation between the structural characteristics of the proteoglycans and the occurrence of growth in the cartilage tissue. 3. Although the amounts of proteoglycans extractable from chondromas and from normal young and adult articular cartilages were almost the same, the chondroma proteoglycans interacted with hyaluronic acid to a lesser extent than those from the normal cartilages. This effect may be due to structural changes in the hyaluronic acid-binding region of the proteoglycan monomers.

Chondroitin sulfates of the epiphysial cartilages of different mammals.

1. The distribution chondroitin 4- and 6-sulfates in the epiphysial cartilages of several mammals are reported. 2. Chondroitin 6-sulfate is present in higher relative proportion in articular surfaces of young and adult epiphysial cartilages in most of the mammals studied. 3. Exception to this was found in some species of the order Rodentia in which chondroitin 4-sulfate was almost the only chondroitin present in young and adult cartilages. 4. These and other results suggest that chondroitin 4-sulfate may be an important component for the calcification process, whereas chondroitin 6-sulfate seems to be related to the integrity of the articular surfaces.