Heterogeneity of protein–polysaccharides of porcine articular cartilage. The chondroitin–sulphate proteins associated with collagen

Pig articular cartilage, from which protein-polysaccharides soluble in iso-osmotic sodium acetate had been removed, was extracted in three further stages with 8m-urea in 2m-sodium acetate and with tris-HCl buffer after bacterial collagenase digestion, followed by the same urea-sodium acetate solution, thus leaving only 2% of the original uronic acid in the tissue. The histological appearance of the cartilage was unaltered until after collagenase digestion. The collagenase used did not affect the viscosity or molecular size of a protein-polysaccharide preparation obtained previously. The protein-polysaccharides in each extract differed in size, amino acid composition and protein content, but protein and keratan sulphate contents were not related to hydrodynamic size, in contrast with protein-polysaccharides extracted previously before collagenase digestion. Hydroxyproline could not be removed from those obtained by the first urea-sodium acetate extraction until degraded by heat. The galactosamine/pentose molar ratio agreed closely with the galactosamine/serine molar ratio that was destroyed on treatment with 0.5m-sodium hydroxide, showing that chondroitin sulphate was attached only to serine residues. From these molar ratios the chondroitin sulphate chains were calculated to be of the same average length in protein-polysaccharides in all three extracts although somewhat shorter than in protein-polysaccharides extracted previously. Some threonine residues were also destroyed on alkali treatment suggesting that keratan sulphate may be attached to threonine. These findings together with previous results show that differences in size, composition and physical state extend to all the protein-polysaccharides in cartilage.     

Studies on protein–polysaccharides from pig laryngeal cartilage. Extraction and purification

1. Protein-polysaccharides of chondroitin sulphate were extracted from fresh laryngeal cartilage at pH6.8 by two procedures. Procedure I consisted of brief low-speed homogenization in 0.15m (iso-osmotic) sodium acetate and procedure II consisted of longer homogenization followed by prolonged extraction in 10% calcium chloride solution. 2. The protein-polysaccharides in both extracts were isolated and purified by precipitation with 9-aminoacridine hydrochloride. They were free from serum proteins, collagen and nucleic acids and also of degradative enzymes. The absence of such enzymes was shown by viscosity measurements on solutions of protein-polysaccharides incubated for up to 24hr. at pH4 and 6.8. 3. Mannose, glucose or fucose were not detected by paper chromatography and only traces of sialic acid were present. 4. The yield with procedure II was twice that with procedure I and the products differed in their protein and glucosamine contents. 5. Hyaluronic acid was unlikely to have been precipitated at an acid pH, so the glucosamine was attributed to keratan sulphate, as serum proteins were absent. There was no free keratan sulphate in the preparation. 6. Both preparations were heterogeneous in the ultracentrifuge, showing at least three components.     

Characterization of protein–polysaccharides of articular cartilage from mature and immature pigs

Protein-polysaccharides of femoral articular cartilage from pigs of ages 9 months and 5 weeks were compared after extraction at pH6.8 with iso-osmotic sodium acetate followed by 0.63m-calcium acetate. The cartilage from the younger animals had a higher moisture content and contained considerably larger amounts of protein-polysaccharide, but less than half as much collagen/g. dry weight, than cartilage from the older pigs. There was notably less keratan sulphate in the fractions from the less mature animals. After gel filtration on 6% agarose, elution profiles of the calcium acetate extracts were similar to those of the sodium acetate extracts of the same tissue. Chemical analyses, however, showed that in both age-groups the extraction procedure had achieved a sequential solubilization of protein-polysaccharides in that the initial extracts contained a higher proportion of keratan sulphate than those that were extracted subsequently. Both extracts from the older animals contained up to 25% of a relatively small protein-polysaccharide that was retarded on 6% agarose and that had a lower protein content and less keratan sulphate than the larger protein-polysaccharides. In contrast, in extracts from the less mature cartilage only about 5% of the protein-polysaccharides were small enough to be retarded by 6% agarose, suggesting that the small components may not be precursors of the larger. The average length of chondroitin sulphate chains, as calculated from the analytical data, was the same in the smaller protein-polysaccharides as in the larger.     

The hypobranchial mucin of the whelk Buccinum undatum L. The polysaccharide sulphate component

1. A polysaccharide sulphate has been isolated from the hypobranchial mucin of the whelk Buccinum undatum. 2. The molecular weight of this polysaccharide, which is a glucan carrying one ester sulphate group per monosaccharide residue, is 1.7x10(5). 3. Some investigations bearing on the location of the ester sulphate groups are reported. 4. The viscosity of the whole mucin has been shown to depend mainly on the glucan sulphate.     

Heterogeneity of protein–polysaccharides of porcine articular cartilage. The sequential extraction of chondroitin sulphate–proteins with iso-osmotic neutral sodium acetate

Protein-polysaccharides of knee-joint cartilage of 9-month-old pigs were extracted sequentially with neutral iso-osmotic sodium acetate after five repeated homogenizations. One-third of the uronic acid originally present in the tissue was brought into solution, about half being in the first extract. The protein-polysaccharides, which were purified by precipitation with 9-aminoacridine, were heterogeneous in size on gel chromatography. The smallest (retarded by 6% agarose) were the most easily extracted since they were most prevalent in the initial extracts and absent from later ones, whereas the proportion of larger molecules increased progressively in successive extracts. Nevertheless a small proportion of the largest molecules (excluded from Sepharose 2B) was present even in the first extract. None of the protein-polysaccharide preparations contained hydroxyproline, and the analyses of their constituent sugars were the same, although there was a progressive increase in the protein content and in the glucosamine/galactosamine molar ratio of successive extracts. In each preparation this molar ratio was invariably greater in larger than in smaller molecules separated by gel filtration. From galactosamine/pentose molar ratios it appeared that the chondroitin sulphate chains were on average about 29 disaccharide units in length in the protein-polysaccharides of each extract, although gel-chromatography and cetylpyridinium chloride elution profiles showed that a somewhat higher proportion of shorter chondroitin sulphate chains occurred in the larger protein-polysaccharides. In the last extract, where the largest molecules predominated, about half could be reversibly dissociated by urea, whereas this had no effect on the protein-polysaccharides of earlier extracts even though these contained some large molecules.     

Characterization of a polysaccharide-protein complex from Ganoderma tsugae mycelium by size-exclusion chromatography combined with laser light scattering

A water-soluble polysaccharide-protein complex (GM3) extracted from the mycelium of Ganoderma tsugae was characterized using size-exclusion chromatography combined with laser light scattering (SEC-LLS). Two peaks coded as fractions I and II appeared in the SEC pattern of GM3 in 0.5 M NaCl aqueous solution, corresponding to the weight-average molecular mass (M(w)) of 355 x 10(4) and 6.3 x 10(4), respectively. The relationship between the radius of gyration ((z)(1/2)) and M(w) showed that molecules of fraction I exhibited more compact coil conformation than that of fraction II in 0.5 M NaCl aqueous solution at 25 degrees C. To clarify the component of polysaccharide and protein in each fraction, the sample GM3 was treated with 0.2 M NaOH aqueous solution to degrade polysaccharide and trypsin to hydrolyze protein. The obtained products were analyzed by SEC combined with detectors such as UV, differential refractive index (DRI) and LLS. The results indicated that both the fractions I and II were protein-bound polysaccharide, but had different protein content and degree of branching, resulting in the difference of the chain conformation.     

Endocytosis and degradation of chondroitin sulphate by liver endothelial cells.

Intravenously administered chondroitin sulphate, chemically labelled by [3H]acetylation of partially deacetylated polysaccharide, was taken up and degraded by the non-parenchymal cells of the liver. Studies using primary monolayer cultures of pure Kupffer cells, liver endothelial cells and parenchymal cells revealed that [3H]chondroitin sulphate was taken up and degraded by the liver endothelial cells only. Binding studies at 4 degrees C with [3H]chondroitin sulphate and 125I-chondroitin sulphate proteoglycan indicated that the glycosaminoglycan and the proteoglycan are recognized by the same binding sites on the liver endothelial cells. The ability of hyaluronic acid to compete with the labelled ligands for binding suggested that the binding site is identical with the recently described hyaluronate receptor on the liver endothelial cells [Smedsrød, Pertoft, Eriksson, Fraser & Laurent (1984) Biochem. J. 223, 617-626]. Fluorescein-labelled chondroitin sulphate proteoglycan accumulated in perinuclear vesicles of the liver endothelial cells, indicating that the proteoglycan is internalized and transported to the lysosomes. The finding that [3H]chondroitin sulphate and 125I-chondroitin sulphate proteoglycan were degraded by the liver endothelial cells to low-molecular-mass radioactive products suggested that both the polysaccharide chain and the core protein were catabolized by the cells.     

Properties of fractionated chondroitin sulphate from ox nasal septa

1. Chondroitin sulphate was isolated from bovine nasal septa by precipitation with cetylpyridinium chloride after digestion of the tissue with papain. 2. The material was divided into two portions, one of which was partially degraded with testicular hyaluronidase. 3. Untreated and hyaluronidase-digested material were fractionated into a total of eleven subfractions by gel chromatography on Sephadex G-200 and Sephadex G-100 respectively. 4. Chemical analyses indicated that the composition of all the fractions was similar to that of chondroitin sulphate. However, electrophoresis revealed a charge-inhomogeneity in the low-molecular-weight fractions obtained after hyaluronidase digestion. 5. The physicochemical properties of the subfractions were investigated by sedimentation-velocity, diffusion and sedimentation-equilibrium studies, osmometry, viscometry and gel chromatography. The individual fractions were essentially monodisperse and showed molecular weights ranging from 2400 to 36000. 6. The relationship between the intrinsic viscosity and the molecular weight was [eta]=5.0x10(-6)xM(1.14), indicating that the chondroitin sulphate molecules assume a shape intermediate between that of a random coil and a stiff rod. 7. The relationship between the sedimentation constant and the molecular weight (>10(4)) was s(0) (20,w)=2.3x10(-2)xM(0.44).     

The characterization of a protein–polysaccharide isolated from Kurloff cells of the guinea pig

Kurloff cells of guinea pigs increase in number and accumulate in the spleen on oestrogen treatment. Because they contain metachromatic inclusions and are considered to be lymphocytes they were examined as a possible model for mucopolysaccharidoses like Hurler's syndrome, where some lymphocytes are also metachromatic. Oestrogen treatment produced a large increase in a glycosaminoglycan resembling chondroitin 4-sulphate in chemical analysis, chromatographic behaviour and i.r. spectrum but with an additional strong band at 805cm(-1). Material isolated without proteolysis behaved on gel chromatography as a multiple-chain protein-polysaccharide whose molecular size was decreased by proteolysis. It contained xylose and galactose in molar proportions with serine, compatible with the presence of the same linkage region as in cartilage chondroitin 4-sulphate proteins and which likewise underwent alkaline beta-elimination. Kurloff glycosaminoglycan chains were significantly longer than chondroitin sulphate chains of cartilage protein-polysaccharides as assessed by gel chromatography and the molar ratios of galactosamine to xylose or to serine. Kurloff cells thus contain intact rather than partially degraded protein-polysaccharide and hence are not analogous to Hurler cells, and their electron micrographs were also different. The purified Kurloff protein-polysaccharide and glycosaminoglycan isolated here has been shown by Marshall, Swettenham, Vernon-Roberts & Revell (1970) to be toxic specifically to macrophages at extremely low concentrations in vitro, unlike chondroitin sulphate of protein-polysaccharides from cartilage. The toxic constituent may account for the i.r.-absorption band at 805cm(-1). Although active incorporation of [(35)S]sulphate occurs at early stages of Kurloff-cell induction (Marshall et al. 1970), the fully developed Kurloff cell studied here showed very low incorporation in vitro and in vivo, suggesting that the inclusions are specialized for the storage of the toxic material.     

Components and antioxidant activity of the polysaccharide from Streptomyces virginia H03

A polysaccharide was isolated from the broth of cultured Streptomyces virginia H03 which was treated by ethanol deposition and savage method to remove the protein, and was purified using Sephadex G-150 column chromatography. The components of the polysaccharide were determined by gas chromatography. The purified polysaccharide was made up of mannose, glucose and galactose, in a 2:1:1 proportion. Its average apparent molecular weight was 3.76 x 10(4) Da which was determined by gel permeation chromatography. In addition, several antioxidant assays were adopted to investigate the antioxidant activity of the polysaccharide in vitro. The results indicated that the purified polysaccharide showed significant antioxidant activity against superoxide anion, hydrogen peroxide and 1,1-diphenyl-2-picrylhydrazyl radical, and lipid peroxidation as with standard antioxidants such as vitamin C. Furthermore, the polysaccharide had a better heat stability than vitamin C, which suggested that the polysaccharide might be a potent useful antioxidant.     

Some structural features of a new sulphated heteropolysaccharide from Padina pavonia

An acid-extractable, water-soluble, polysaccharide sulphate, isolated from Padina pavonia, comprised variable proportions of glucuronic acid, galactose, glucose, mannose, xylose, and fucose in addition to a protein moiety. Partial acid hydrolysis and autohydrolysis of the free acid polysaccharide yielded several oligosaccharides. Evidence from periodate oxidation studies indicated that the inner polysaccharide portion is composed of (1 → 4)-linked β-D-glucuronic acid, (1 → 4)-linked β-D-mannose and (1 → 4)-linked β-D-glucose residues. The heteropolymeric partially sulphated exterior portion is attached to the inner part and comprises various ratios of (1 → 4)-linked β-D-galactose, β-D-galactose-3-sulphate residues, (1 → 4)-linked β-D-glucose residues, (1 → 2)-linked α-L-fucose 4-sulphate residues and (1 → 3)-linked β-D-xylose residues.     

The effect of beta-D-xylosides on chondroitin sulphate biosynthesis in embryonic chicken cartilage in the absence of protein synthesis inhibitors.

Incorporation of [35S]]sulphate, [3H]glucose and [3H]serine into glycosaminoglycans and proteoglycans of embryonic-chicken sternum was measured in vitro in incubation medium containing 4-methylumbelliferyl beta-D-xyloside or p-nitrophenyl beta-D-xyloside at low concentrations, and in the absence of inhibitors of protein synthesis. Incorporation of sulphate was decreased by 80% in incubations in which 1mM-4-methylumbelliferyl beta-xyloside or 2.5 mM-p-nitrophenyl beta-xyloside was present; under these conditions, serum factors stimulated incorporation to only a small extent. When the concentration of the xyloside was decreased tenfold, incorporation of sulphate was inhibited by 60-70%, but when normal human serum or L-3,3',5-tri-iodothyronine or both were also added to the incubation medium, incorporation was markedly stimulated. Experiments in which [35S]sulphate and [3H]glucose were incorporated simultaneously, and enzymic analysis of glycosaminoglycans formed in such experiments, indicated that chondroitin sulphate formed in the presence of 0.1 mM-4-methylumbelliferyl beta-xyloside contained 30-40% less sulphate than did chondrotin sulphate synthesized in the absence of xylosides. Similar experiments, with [3H]serine instead of [3H]glucose, suggested also a 20-30% decrease in chain length of the chondroitin sulphate; this was confirmed by direct gel filtration of labelled glycosaminoglycans on a calibrated column. Incorporation of [3H]glucose or [3H]serine was stimulated by serum and tri-iodothyronine in parallel with incorporation of sulphate. The changes seen in the total chondroitin sulphate were mirrored in the major proteoglycan fraction, purified by isopycnic centrifugation of salt-extracted proteoglycans. The labelling pattern of chondroitin sulphate from this proteoglycan indicated that decreased sulphation of chondroitin sulphate was largely due to the inferior ability of short polysaccharide chains to accept sulphate, with some direct interference with transfer of sulphate to all chains. The results also suggested that the action of serum factors on synthesis of proteochondroitin sulphate is exercised at the level of either protein synthesis or transport to the sites of initiation of polysaccharide synthesis.     

Mode of degradation of the chondroitin sulphate proteoglycan in rat costal cartilage

1. Chondroitin sulphate was isolated from different regions of rat costal cartilage after extensive proteolysis of the tissues. The molecular weight, determined by gel chromatography, of the polysaccharide obtained from an actively growing region (lateral zone) near the osteochondral junction was higher than that of the polysaccharide isolated from the remaining portion of the costal cartilage (medial zone). 2. In both types of cartilage the molecular weight of chondroitin sulphate, labelled with [(35)S]sulphate, remained unchanged in vivo over a period of 10 days, approximately corresponding to the half-life of the chondroitin sulphate proteoglycan. The molecular-weight distribution of chondroitin [(35)S]sulphate, labelled in vivo or in vitro, was invariably identical with that of the bulk polysaccharide from the same tissue. It is concluded that the observed regional variations in molecular-weight distribution were established at the time of polysaccharide biosynthesis. 3. In tissue culture more than half of the (35)S-labelled polysaccharide-proteins of the two tissues was released into the medium within 10 days of incubation. The released materials were of smaller molecular size than were the corresponding native proteoglycans. In contrast, the molecular-weight distribution of the chondroitin [(35)S]sulphate (single polysaccharide chains) remained constant throughout the incubation period. 4. A portion (about 20%) of the total radioactive material released from (35)S-labelled cartilage in tissue culture was identified as inorganic [(35)S]sulphate. No corresponding decrease in the degree of sulphation of the labelled polysaccharide could be detected. These findings suggest that a limited fraction of the proteoglycan molecules had been extensively desulphated. 5. It is suggested that the initial phase of degradation involves proteolytic cleavage of the proteoglycan, but the constituent polysaccharide chains remain intact. The partially degraded proteoglycan may be eliminated from the cartilage by diffusion into the circulatory system. An additional degradative process, which may occur intracellularly, includes desulphation of the polysaccharide, probably in conjunction with a more extensive breakdown of the polymer.     

Biosynthesis of heparin. Relationship between the polymerization and sulphation processes.

Incubation of a mouse mastocytoma microsomal fraction with UDP-[3H]GlcA and UDP-GlcNAc yielded proteoglycans containing non-sulphated polysaccharide chains. Similar incubations performed in the presence of sulphate donor 3'-phosphoadenosine 5'-phosphosulphate (PAPS) produced both sulphated and non-sulphated proteoglycans, which were separated by chromatography on DEAE-cellulose Analysis by gel chromatography of single polysaccharide chains, released from the proteoglycans by alkali treatment, showed that the non-sulphated chains produced during incubation for 5 min or 25 min, either in the absence or in the presence of PAPS, were of fairly small molecular size, with an average peak Mr of approx. 10 x 10(3)-15 x 10(3). In contrast, the sulphated chains exceeded Mr 100 x 10(3) Pulse-chase experiments suggested that sulphated chains were capable of further elongation. These results indicate that sulphation promotes, by so far unknown mechanisms, further chain elongation. Sulphated proteoglycan (retarded on DEAE-cellulose chromatography) isolated after similar incubation of the microsomal fraction for 1 min only was found to contain a mixture of sulphated and virtually non-sulphated polysaccharide chains. However, when [35S]PAPS was included in the incubations, some 35S was found to be associated, essentially as N-sulphate groups, also with the latter type of chains, preferentially the high-Mr fraction. These results are interpreted in terms of a biosynthetic model by which the heparin proteoglycan is generated through transient interactions of macromolecular intermediates with distinctly separate complexes of membranebound enzymes.     

The identification and purification of multiple forms of theta-haemolysin (theta-toxin) of Clostridium perfringens type A.

The theta-haemolysin of Clostridium perfringens was purified from culture supernatant fluids of type A strains by fractional ammonium sulphate precipitation and isoelectric focusing in narrow pH 5 to 8 gradients. Four components detected on electrofocusing were designated theta-1(pI6-8to6-9),theta-2(pI6-5to6-6),theta-3(pI6-1to6-3) and theta-4(pI5-7to5-9). Specific activities ranged from 0-4 x 10-6 to 1-2 x 10-6 haemolytic units/mg protein and 2950 to 3600 LD-50/mg protein. Each haemolytic component was activated by cysteine hydrochloride, and inactivated by cholesterol, by addition of sheep erythrocyte ghosts and by heating at 60 degrees C for 10 min; mouse erythrocytes were more resistant than sheep erythrocytes to haemolysis. A reaction of identity was obtained between components in gel diffusion. Sodium dodecyl sulphate polyacrylamide discgel electrophoresis gave molecular weights in the range 59,000 to 62,000 for each component. A similar value was obtained for theta-1 on density gradient ultracentrifugation. Although the multiple forms were free of 11 factors present in culture supernatants, crossed immunoelectrophoresis and disc gel electrophoresis revealed minor contaminants. These studies reveal that theta-haemolysin has physical properties in common with other oxygen-labile haemolysins.     

Identification of the core proteins in proteoglycans synthesized by vascular endothelial cells.

Proteoglycans, metabolically labelled with [3H]leucine and 35SO4(2-), were isolated from the spent media and from guanidinium chloride extracts of cultured human umbilical-vein endothelial cells by using isopycnic density-gradient centrifugation, gel filtration and ion-exchange h.p.l.c. The major proteoglycan species were subjected to SDS/polyacrylamide-gel electrophoresis before and after enzymic degradation of the polysaccharide chains. The cell extract contained mainly a heparan sulphate proteoglycan that has a buoyant density of 1.31 g/ml and a protein core with apparent molecular mass 300 kDa. The latter was heterogeneous and migrated as one major and one minor band. After reduction, the apparent molecular mass of the major band increased to approx. 350 kDa, indicating the presence of intrachain disulphide bonds. The proteoglycan binds to octyl-Sepharose and its polysaccharide chains are extensively degraded by heparan sulphate lyase. The proteoglycans of the medium contained 90% of all the incorporated 35SO4(2-). Here the predominant heparan sulphate proteoglycan was similar to that of the cell extract, but was more heterogeneous and contained an additional core protein with apparent molecular mass 210 kDa. Furthermore, two different chondroitin sulphate proteoglycans were found: one 200 kDa species with a high buoyant density (approx. 1.45 g/ml) and one 100 kDa species with low buoyant density (approx. 1.3 g/ml). Both these proteoglycans have a core protein of molecular mass approx. 47 kDa.     

Structural characteristics of a bioactive polysaccharide from Sorghum arundinaceum

A polysaccharide, an alpha-D-glucan with an apparent molecular weight of 6.85 x 10(4), called PSa glucan, was isolated from fresh seeds of Sorghum arundinaceum by fractionation on Sephacryl S-300 HR and Sephadex G-25. Chemical and spectroscopic studies indicated that it has a highly branched glucan type structure composed of alpha-(1-->4) linked D-glucopyranose residues with (1-->3), (1-->6) branching points, and a significant amount of alpha-(1-->6) branching to alpha-(1-->3) linked D-glucopyranose residues. The anti-inflammatory activity of the polysaccharide was performed using the capillary permeability assay.     

Fermentation of bovine endothelial cells for preparation of endothelial cell-surface heparan sulphate

The polysaccharide chains of a proteoheparan sulphate located on the endothelial cell surface are responsible for athrombogenicity of blood vessel walls. Mass cultivation of endothelial cells is the only way to isolate adequate amounts of this proteoheparan sulphate. In order to establish a method for fermentation of bovine endothelial cells, colonization of microcarriers, growth phase and cultivation of confluent carriers were optimized. The colonization process was varied relative to the number of beads, number of cells, total volume and kind of vessel. Two basal media were tested at different serum contents by growth assays. The same basal media without serum were supplemented with mitogen, bovine lipoprotein, insulin and transferrin and tested by activity assays on confluent cultures. The best method yields more than 80% of the cells on microcarriers. During the fermentation glucose and lactate concentrations were measured at constant perfusion rate and glucose consumption and lactate production were determined. Under optimized conditions we achieved a final cell titre of 4 x 10(9) cells/l and a calculated cell density of 7-9 x 10(4) cells/cm2 offered substrate surface. The minimal doubling time of the cell culture was about 18 h under optimized fermentation conditions. Removal of the core-protein by enzymatic digestion or beta-elimination releases the endothelial cell surface heparan sulphate.     

Interactions of an intact proteoglycan and its fragments with basic homopolypeptides in dilute aqueous solution

The interactions between a proteoglycan and cationic polypeptides have been investigated by the use of circular-dichroism spectroscopy. The interaction produces an induced conformational change for poly(l-arginine) and poly(l-lysine), similar to the effects previously reported for mucopolysaccharide-polypeptide mixtures. For bovine nasal septum proteoglycan, the interactions are similar to those for chondroitin 4-sulphate, which comprises approximately 63% of the total polysaccharide. The results also suggest that the interactions produce a conformational change in the protein core. Similar studies for the Smith-degradation product show that the protein core can adopt a substantial alpha-helical content and is capable of interactions with poly-(l-arginine). The interactions for chondroitin sulphate ;doublets' are significantly different from those for the separated chains, indicating that the arrangement of the polysaccharide side chains in pairs (and larger groups) along the protein backbone contributes to the interaction properties of the intact proteoglycan.     

Structure of an α-D-galactosaminoglycan from Physarum polycephalum Spherule walls

The spherule walls Physarum polucephalum have been reexamined and found to contain 88% of galactosamine (as anhydrogalactosamine), 6.80% of protein, 4.7% of phosphate groups, and a small proportion of acetyl groups (0.5%). Methylation studies indicated that the spherule-wall polysaccharide is a long-chain galactosamino- glycan linked exclusively (1→4) and without phosphate linkages. The specific optical rotation of this unique glycan. [x]_D, + 118° (6_M HCI), indicated that it is α-D-linked.