Deuterium magnetic resonance study of the interaction between chondroitin sulfate and human plasma low density lipoproteins

[2H]Chondroitin sulfate was prepared by partial N-deacetylation of chondroitin sulfate (via hydrazinolysis) followed by treatment with [2H6]acetic anhydride. 2H NMR spectra of [2H]chondroitin sulfate in the presence of human plasma low density lipoprotein provide evidence for a soluble complex stoichiometry of 3 (and possibly 2) lipoproteins per polysaccharide molecule, and allow a rough estimation of the dissociation constant Kd.

On the structure of bovine articular cartilage high density proteoglycans. Isolation of the keratan sulfate and chondroitin sulfate side chains

The structure of adult bovine articular cartilage high density proteoglycans (PG-I) was studied by degradation with Pronase, chondroitinase ABC, and alkaline borohydride treatments and fractionation and analysis of the products. The keratan sulfate (KS) peptides were rich in glutamic acid, proline, and serine and had a low glycine content. The chondroitin sulfate (CS) peptides had a high content of serine, glycine, and glutamic acid and a much lower proline content than the KS peptides. The data indicate that the KS and CS chains occur in more distinct regions of the protein core(s) than in bovine nasal cartilage PG. After alkaline borohydride treatment there was an almost quantitative conversion of xylose to xylitol and galactosaminitol was the only hexosaminitol detected in KS fractions. The results obtained indicated that the alkali-labile bonds linking the CS and KS chains are the same as those reported to occur in other cartilage PGs. The Mr of the KS chains calculated from the glucosamine and galactosaminitol contents gave values of 6,000-7,000, although gel chromatography and light scattering measurements indicated considerable heterogeneity. The KS and CS chains were quantitatively precipitated by cetylpyridinium chloride and the KS and a portion (15%) of the CS chains were found to be soluble in 1% cetylpyridinium chloride. The abnormal solubility properties of the CS chains in the presence of 1% cetylpyridinium chloride is thought to be due to their low sulfate content. The molecular weight of the remainder of the CS chains, based on the ratio of xylitol to galactosamine, varied from 6,500 to 16,000. The low Mr CS chains were rich in 6-sulfated disaccharides whereas the higher Mr chains had a higher content of 4-sulfated disaccharides. The ratio of galactose to xylitol also varied with Mr. These results indicate similarities in the structure of the adult bovine articular cartilage PG-Is to other cartilage high density PGs. The heterogeneities observed in the composition of the KS and CS chains, and their occurrence in relatively distinct regions of the protein core(s) indicate, however, that there is still much to be learned about the structure of these complex macromolecules.

Biosynthesis and secretion of dermatan sulphate proteoglycans in cultures of human skin fibroblasts

Fibroblasts in culture were incubated with [3H]leucine and [35S]sulphate for 1-24 h. A large glucuronic acid-rich and a small iduronic acid-rich dermatan sulphate proteoglycan were isolated with the use of isopycnic density-gradient centrifugation, ion-exchange and gel chromatography. After 3 h the accumulation in the cell layer of the small proteoglycan reached a steady state, whereas the large one continued to increase, albeit more slowly. In the medium both proteoglycans accumulated 'linearly', although the large one appeared somewhat later than the small one. The composition of the polysaccharide chains and the size of the protein cores did not vary during the experiment. The two proteoglycans were synthesized at approximately similar rates, but were distributed differently in the culture. The small proteoglycan was mainly confined to the medium, whereas the large one was found in the medium as well as in a cell-associated pool. There was an intracellular accumulation of iduronic acid-rich dermatan sulphate as free polysaccharides.

Pregnancy-related changes in the connective tissue of the ovine cervix

During the course of gestation, changes in the metabolism and chemical composition of the cervical connective tissue occur. The concentrations of collagen, proteoglycan and hyaluronate in the cervix decrease with time of pregnancy, while there is a small but significant increase in tissue hydration. The collagen network loses its dense, ordered appearance and assumes a loose, frayed, disoriented structure. A small molecular weight dermatan sulphate proteoglycan with Kav = 0.48 on Sepharose CL-4B has been isolated from pregnant and nonpregnant ovine cervix. Proteoglycans isolated from dilated cervix yield a second peak at the excluded volume of a Sepharose CL-4B column which may represent a new proteoglycan species, or represent a proteoglycan monomer with larger glycosaminoglycan constituents. The rate of synthesis of proteoglycan is enhanced during pregnancy, and doubles in the time between 140 days and term (dilated). The increased rate of proteoglycan synthesis in the presence of a diminishing hexuronate concentration in the pregnant cervix is indicative of enhanced proteoglycan turnover. This may provide some insight into the mechanism whereby a new matrix with altered mechanical properties is produced, since a rapid turnover of matrix components enables a remodeling of the connective tissue framework. This reorganization of the matrix is discussed with respect to parturition.

Protamine modulation of sulfotransferase activity from chicken embryo epiphyseal cartilages changes with the degree of sulfation of the acceptor

The affinity of a chicken embryo epiphyseal cartilage sulfotransferase, whose endogenous acceptor has been removed by protamine, was 10 times greater for partially sulfated chondroitins than for totally desulfated chondroitins, suggesting that the sulfation of these glycosaminoglycans increased sharply after the addition of the first sulfate groups to the polysaccharide. This sulfotransferase was activated by protamine, presenting Michaelis-Menten kinetics when transferring [35S]sulfate from [35S]3'-phosphoadenosine 5'-phosphosulfate to the totally desulfated chondroitin, whereas sigmoidal kinetics was observed when partially sulfated chondroitin 6-sulfate was employed as substrate. This sigmoidal kinetics was attributed to the combined effect of protamine that both activated the enzyme and removed the sulfate acceptor from solution. The effect of other basic substances on the activity of the sulfotransferase was also reported.

Incorporation of 35S-sulfate and 3H-glucosamine into heparan and chondroitin sulfates during the cell cycle of B16-F10 cells

Changes in glycosaminoglycan composition occurring during the cell cycle were determined in B16-F10 cells sorted flow cytometrically with respect to DNA content. Incorporation of 35S-sulfate into heparan sulfate and chondroitin sulfate of unsorted and G1,S, and G2 +M sorted cells was determined following chondroitinase ABC or nitrous acid treatment; the incorporation into surface material was measured as the difference between the radioactivity of control and trypsin-treated cells. Incorporation of 35S-sulfate and 3H-glucosamine into cetyl pyridinium chloride (CPC)-precipitable material was characterized before and after chondroitinase or nitrous acid treatment by Sephadex G50 chromatography. Long-term (48 h) and short-term (1 h) labeling studies demonstrate that (a) the amount of total cellular chondroitin sulfate is greater than that of heparan sulfate, with larger amounts of unsulfated heparan than chondroitin being present; (b) the rate of turnover of heparan sulfate is greater than that of chondroitin sulfate; (c) greatest short-term incorporation of 3H-glucosamine into CPC-precipitable material occurs during S phase; and (d) the rate of turnover of both heparan sulfate and chondroitin sulfate is decreased in S phase relative to G1 and G2 + M.

Heparan sulfate and dermatan sulfate from the liver of a patient with Hurler syndrome: high performance liquid chromatography of their degradation products after incubation with alpha-L-iduronidase-deficient fibroblasts

Using a high performance liquid chromatography method, degradation products of heparan sulfate (HS) and dermatan sulfate (DS) were investigated after incubation of control and alpha-L-iduronidase-deficient fibroblasts with HS or DS. Characteristic elution profiles of the degradation products were obtained from the respective alpha-L-iduronidase-deficient fibroblasts. Moreover, alpha-L-iduronidase in control fibroblasts was resolved into two distinct components, forms A and B, on DEAE-cellulose column chromatography. Form A alpha-L-iduronidase could degrade HS, but not DS. Conversely, form B alpha-L-iduronidase could not degrade HS, but could degrade DS.

Mapping by monoclonal antibody detection of glycosaminoglycans in connective tissues

Chondroitin sulphate proteoglycans are widespread connective tissue components and chemical analysis of cartilage and other proteoglycans has demonstrated molecular speciation involving the degree and position of sulphation of the carbohydrate chains. This may, in turn, affect the properties of the glycosaminoglycan (GAG), particularly with respect to self-association and interactions with other extracellular matrix components. Interactions with specific molecules from different connective tissue types, such as the collagens and their associated glycoproteins, could be favoured by particular charge organizations on the GAG molecule endowed by the sulphate groups. So far, it has not been possible to identify and map chondroitins of differing sulphation in tissues, but we have now raised three monoclonal antibodies which specifically recognize unsulphated, 4-sulphated and 6-sulphated chondroitin and dermatan sulphate. These provide novel opportunities to study the in vivo distribution of chondroitin sulphate proteoglycans. We demonstrate that chondroitin sulphates exhibit remarkable connective tissue specificity and furthermore provide evidence that some proteoglycans may predominantly carry only one type of chondroitin sulphate chain.

The periphery of the developing collagen fibril. Quantitative relationships with dermatan sulphate and other surface-associated species

Dermatan sulphate, hydroxyproline and collagen fibril diameters were measured in flexor tendons from chick and calf limbs, from early in embryonic development to maturity. The collagen fibril is viewed as a long thin cylinder. A species X present at the periphery of the cylinder, regularly and specifically arrayed along the fibril, should then satisfy the relationship [X]/[collagen]r = k where [X] and [collagen] are tissue concentrations of X and collagen, and r is the fibril radius. Throughout the developmental period studied, dermatan sulphate (i.e.X) in chick, calf and rat tendons fits the relationship, implying that it is specifically, regularly and entirely associated with collagen fibrils, thus confirming and extended previous electron histochemistry [Scott & Orford (1981) Biochem. J. 197, 213-216]. This approach explains the pattern of change of dermatan sulphate content during development of the tendon. The findings imply that the dermatan sulphate proteoglycan-collagen interaction is evolutionarily highly conserved. The relationship [X]/[collagen]r = k is used to show that surface concentrations of covalently bound species, such as extension propeptides, can be easily assessed, given the data base described in paragraph 1 above.

Phosphorylation of chondroitin sulfate in proteoglycans from the swarm rat chondrosarcoma

Proteoglycans isolated from the Swarm rat chondrosarcoma were shown to contain 35 mol of phosphate/mol of proteoglycan. While 20% of this phosphate was released by digestion with dilute alkali in the presence of sodium borohydride and is presumably of the phosphoserine/phosphothreonine type, 78% of the phosphate copurified with the peptide-free chondroitin sulfate chains. When chondroitin sulfate chains purified by ethanol precipitation or Sephacryl S200 column chromatography were digested with chondroitinase AC and the digests chromatographed on Bio-Gel P-4, the phosphate co-migrated with a carbohydrate fragment that contained 2 glucuronic acid (one as delta 4,5-unsaturated sugar), 1-galactosamine, 2-galactose, and 1-phosphate residue/xylitol. A second fragment of similar composition but lacking phosphate was also recovered in a ratio of about 3 to 1 relative to the phosphorylated fragment. The phosphate in the chondroitin sulfate linkage region fragment had the alkaline phosphatase sensitivity as well as 31P NMR spectra of a monophosphate esterified to a secondary sugar alcohol. The phosphate was localized on the C-2 of the chain initiating xylose since these residues as xylitol showed a delayed release during acid hydrolysis and the xylitol was recovered intact after periodate oxidation. In the chondrosarcoma, 2-phosphoxylose appears to be a normal synthetic product since [32P]phosphate was readily incorporated into the proteoglycan and the incorporated isotope had similar biochemical properties as the unlabeled phosphate.

Isolation and structural studies of heparan sulfates and chondroitin sulfates from three species of molluscs

The isolation and some structural features of heparan sulfates and chondroitin sulfates from three species of molluscs (Pomacea sp., Tagelus gibbus, and Anomalocardia brasiliana) are reported. It is shown that heparan sulfates with structural similarities to the ones found in mammals are present in the three molluscs analyzed. All the heparan sulfates were degraded by heparitinases I and II to four distinct unsaturated disaccharides with the same properties as the ones present in heparan sulfates of mammalian origin. This suggests that these four disaccharide units are maintained through the evolution. Furthermore, the proportion of these units varied in the heparan sulfates according to the species of origin. The chondroitin sulfates, on the other hand, exhibit different structural features according to the species of origin. For instance, by the action of chondroitinase AC, 4- and nonsulfated disaccharides are produced from Pomacea chondroitin, whereas 4- and 6-sulfated disaccharides are formed from Tagelus and Anomalocardia. The possible role of these compounds in cell recognition and/or adhesiveness is discussed in view of the present findings.

Sulfated glycosaminoglycans inhibit hyaluronic acid synthesizing activity in mouse cumuli oophori

Prior to ovulation, the cumulus cells that surround the oocyte become embedded in a matrix containing hyaluronic acid (HA). Sulfated glycosaminoglycans (GAGs) prevent the hormonally stimulated deposition of this matrix in vitro. The goal of this project was to determine the effect of sulfated GAGs on the HA-synthesizing activity of the cumuli oophori. This activity was measured in lysates of mouse cumuli oophori after stimulation of isolated cumulus cell-oocyte complexes with follicle-stimulating hormone (FSH) in the presence or absence of sulfated GAGs. FSH treatment resulted in a 5-fold stimulation of HA-synthesizing activity by 3 h in vitro. This induction was inhibited in a dose-dependent manner by heparin and chondroitin sulfate B. However, addition of heparin or chondroitin sulfate B to the assay mixtures containing lysates of FSH-stimulated cumuli oophori had no effect on the HA-synthesizing activity. Heparin also suppressed HA-synthesizing activity stimulated by dibutyryl cyclic adenosine monophosphate. Heparin inhibited the continued increase in hyaluronic acid synthesizing activity when added to cultures after 3 h of FSH stimulation. Also, addition of heparin to cultures of cumuli oophori after 3 or 6 h of incubation in medium containing FSH resulted in only partial cumulus expansion. These results indicate that sulfated GAGs, which are found in ovarian follicular fluid and are a component of extracellular matrix, inhibit some cellular process(es) that results in increased HA-synthesizing activity. The sulfated GAGs also have the ability to suppress HA-synthesizing activity after it has been induced to levels that result in partial cumulus expansion. However, the sulfated GAGs are not direct enzyme inhibitors.

Chondroitin sulfate: an indicator of atresia in bovine follicles

Estrogen (E), progesterone (P), and chondroitin sulfate (CS) concentrations in follicular fluid from 172 small (5-mm), 213 medium (6- to 10-mm), and 91 large (11- to 20-mm) individual bovine follicles were measured. Follicular health was classified by three methods; 1) histological examination for mitotic and pyknotic granulosa cell nuclei, 2) follicular E concentrations, and 3) the ratio of E to P (E/P). All three methods were significantly correlated. The highest correlation existed between follicular E concentrations and E to P ratio. Atretic follicles contained significantly less E and greater concentrations of P and CS than healthy follicles. CS concentrations significantly decreased as follicle size increased. E and P values did not change in relation to follicle size regardless of follicle health. Concentrations of E were significantly negatively correlated to P and CS, but P and CS were significantly positively correlated among all follicles. Thus, healthy follicles had elevated concentrations of E with relatively low P and CS, whereas atretic follicles had low amounts of E with elevated P and CS.

Selective hydrolysis of chondroitin sulfates by hyaluronidase

Chondroitin 4-sulfate and chondroitin 6-sulfate were incubated with testicular hyaluronidase in the presence of excess beta-glucuronidase. The beta-glucuronidase caused rapid removal of the nonreducing terminal beta-D-glucuronosyl residues from the oligosaccharides formed by the action of the hyaluronidase, destroying the oligosaccharide acceptors required for the transglycosylation activity of hyaluronidase and releasing free D-glucuronic acid at a rate that was equal to the rate of the hyaluronidase-catalyzed hydrolysis. When hyaluronidase was assayed at 37 degrees C in the presence of 0.05 M NaCl, 0.05 M Na2SO4, and 0.1 M sodium acetate at pH 5, chondroitin 4-sulfate was hydrolyzed at 1.5 times the rate found for chondroitin 6-sulfate. When hyaluronidase was assayed at 45 degrees C in 0.06 M sodium acetate at pH 6, chondroitin 4-sulfate was hydrolyzed at 8 times the rate observed for chondroitin 6-sulfate. Under the pH5 conditions, the chondroitin 4-sulfate was converted to a mixture of tri- and pentasaccharides, while the chondroitin 6-sulfate was converted primarily to a mixture of penta- and heptasaccharides, with only a small amount of trisaccharide. Under the pH 6 conditions, the chondroitin 4-sulfate was converted to a mixture of penta- and heptasaccharides, with only a small amount of trisaccharide, but the products from chondroitin 6-sulfate were a mixture of oligosaccharides ranging in degree of polymerization from 7 to 25 monosaccharides per oligosaccharide. End-group analyses of the products formed at pH 6 showed that both substrates were cleaved preferentially at the glycosidic bonds of the 4-sulfated disaccharides.(ABSTRACT TRUNCATED AT 250 WORDS)

Biosynthesis of dermatan sulfate. II. Substrate specificity of the C-5 uronosyl epimerase

Epimerization of D-glucuronosyl residues to L-iduronosyl ones during biosynthesis of dermatan sulfate involves an abstraction of the C-5 hydrogen of the target sugar residue. After inversion, a hydrogen from the medium is reinserted into the uronosyl residue. In the present study, microsomal enzyme prepared from cultured embryonic skin fibroblasts was incubated with dermatan or chondroitin in the presence of 3H2O of high specific activity. Incubation resulted in incorporation of tritium on C-5 of uronosyl residues of the substrates. The rate of the reaction was highest for dermatan. Incubation of the products with chondroitinase ABC released essentially all the tritium. Dermatan sulfate and chondroitin sulfate were inactive as substrates, which indicates that epimerization takes place before sulfation. Analyses of the product obtained after incubation of chondroitin in 3H2O-containing medium for different incubation times showed that tritium accumulated first in L-iduronosyl residues. Later, tritium was also found in D-glucuronosyl residues. The reverse situation was observed when dermatan was used as substrate. After extended incubation times, the ratio of D-[3H]glucuronic acid to L-[3H]iduronic acid in both dermatan and chondroitin reached a value of 85/15, which may reflect the equilibrium value. Digestion of labeled chondroitin with chondroitinase AC and oxidation of labeled dermatan with periodate showed that after 96 h of incubation with the epimerase and 3H2O, most of the uronic acid residues had been involved in the reaction. Both products were composed of long blocks of D-glucuronic acid-containing disaccharides interrupted by a few L-iduronic acid-containing disaccharides arranged singly of in clusters of two to three. Reincubation of the 3H-labeled products originating from dermatan or chondroitin with the epimerase resulted in release of tritium, which was linear with time and with increasing protein concentration.

Activation of heparin cofactor II by heparin and dermatan sulfate

Heparin cofactor II is a glycoprotein present in human plasma at a concentration of approximately 1.2 microM. It inhibits thrombin by forming a stable, 1:1 complex with the protease. The rate of complex formation is increased approximately 1,000-fold by heparin or dermatan sulfate. Heparin cofactor II appears to be the only thrombin inhibitor in plasma that can be activated by dermatan sulfate. Platelet factor 4 abolishes the activation of heparin cofactor II by dermatan sulfate, but plasma histidine-rich glycoprotein does not. Heparin cofactor II is activated by dermatan sulfate oligosaccharides that are at least 12-14 sugar residues in length and contain a high-affinity binding site for the inhibitor protein.

Isolation and characterization of peptidoglycans in urine from patients with mucopolysaccharidoses

Urinary dermatan sulfate (DS) and heparan sulfate (HS) were purified from mucopolysaccharidosis patients. DS shows average mol. wt 8600-12,000 (approx. one half of tissue DS), iduronic acid content 99.1-99.6% (81.8% in tissue DS), core peptide mostly di- or tri-peptide (--Ser--Gly--or--Ser--Gly--Glu--). Molecular weight of HS ranged from 2500 to 20,000, averaging about 5000. Highly sulfated HS was found in the low molecular weight fraction, and no bound core peptide. By contrast, HS in the high molecular weight fraction bound one sulfate per repeating unit, which include core peptide.

Effects of chondroitin sulfate on metabolism of trabecular meshwork

Glycosaminoglycans are believed to play a role in the physiological functions of trabecular meshwork. The effects of chondroitin sulfate on the metabolism of trabecular meshwork were studied by replacing the aqueous humor in the right eye (experimental eye) of 12 albino rabbits with 0.3 ml of chondroitin-4-sulfate solution (10 mg ml-1 in glucose-supplemented phosphate buffered saline). The aqueous humor in the left eye (control eye) was replaced with the phosphate buffered saline-glucose solution in the same manner. The intracameral procedures were performed twice a week for four weeks (initial injection period), and then discontinued for another four weeks (resting period). No significant or prolonged increase in the intraocular pressure was observed during either period in any eyes. Subsequent intracameral injections performed after the resting period, however, caused an intraocular pressure elevation in 10 of the 12 experimental eyes. During this second injection period, the injections were carried out whenever the intraocular pressure of experimental eyes dropped to the control value. The pressure generally remained 5-10 mmHg above that of the control eyes for periods ranging from two days to four weeks. In the eyes with elevated intraocular pressure, light microscopy showed that the trabecular beams were compact and sclerotic and the intertrabecular spaces were narrower. Chamber angle tissues obtained from the eyes with elevated intraocular pressure incorporated more radioactive precursors into glycosaminoglycans than those from the control eyes. The synthesis of glycosaminoglycans and the metabolism of trabecular meshwork seemed to be modified by the long-term chondroitin sulfate treatment.

Immunofluorescence studies of chondroitin sulfate proteoglycan biosynthesis: the use of monoclonal antibodies

Several monoclonal antibodies which recognize different antigenic determinants of chondroitin sulfate proteoglycan were used to study chondroitin sulfate proteoglycan biosynthesis in chicken chondrocyte cultures. The intracellular sites of synthesis and processing and extracellular deposition in matrix were localized by double immunofluorescence reactions. One rat monoclonal antibody, S103L , which recognizes an antigenic determinant of the core protein of the chicken cartilage chondroitin sulfate proteoglycan monomer, was used to identify both extracellular chondroitin sulfate proteoglycan and intracellular compartments containing chondroitin sulfate proteoglycan precursors. Intracellular staining with S103L was localized to perinuclear regions, and, in some chondrocytes, to a few other cytoplasmic vesicles as well. When chondrocytes were not fed for several days, intracellular chondroitin sulfate proteoglycan precursors were accumulated in larger compartments distributed throughout the cytoplasm. Polyclonal chondroitin sulfate proteoglycan antibodies displayed similar staining characteristics. In contrast, several of the monoclonal antibodies, including the rat monoclonals S11D and P100D , and the mouse monoclonals 1-B-5, 3-B-3 and 9-A-2, did not recognize native chondroitin sulfate proteoglycan, but reacted only with chondroitinase ABC-digested (and/or hyaluronidase-digested) chondroitin sulfate proteoglycan. These antibodies were particularly useful in the demonstration of the extracellular codistribution of chondroitin sulfate proteoglycan with either type II collagen or fibronectin. In other experiments, the monoclonal antibodies to chondroitin sulfate proteoglycan served to demonstrate that the perinuclear subset of intracellular compartments is uniquely involved in the addition of chondroitin sulfate oligosaccharides to the chondroitin sulfate proteoglycan core protein. Lastly, using the mouse monoclonal 5-D-4, which recognizes keratan sulfate determinants, the perinuclear region was identified as the site for keratan sulfate addition. Results suggest heterogeneity of keratan sulfate synthesis at the level of individual chondrocytes, even for cells apparently containing equivalent amounts of intracellular chondroitin sulfate proteoglycan.

The NH2-terminal amino acid sequence of bovine skin proteodermatan sulfate

Deglycosylation of bovine skin proteodermatan sulfate with chondroitinase ABC yielded a protein core with an apparent molecular weight of about 45,000. The amino acid sequence of this preparation was determined up to position 24. This region was enriched in acidic amino acids and proline compared with the whole protein core and it was predicted to be highly folded. The amino acid sequence determined in these experiments has a gap at position 4. Results obtained after beta-elimination-sulfite addition showed that residue 4 was an O-substituted hydroxyamino acid. The latter was identified as serine by sequencing the NH2-terminal region of the protein core (Mr approximately 43,000) isolated after a more complete deglycosylation of the proteoglycan with anhydrous HF. Serine 4 may be an attachment site for one of the few dermatan sulfate chains present in the proteoglycan.

Histochemical identification of sulfation position in chondroitin sulfate in various cartilages

The ability of chondrocytes to synthesize chondroitin-4-sulfate (C4S) as opposed to chondroitin-6-sulfate (C6S) is a phylogenetically related phenomenon seen among adult higher vertebrates and developmentally during the embryogenesis of these vertebrates. While the embryonic cartilage may be initially a C6S matrix, C4S synthesis is seen to develop with time. We have histochemically localized these differences in sulfation with the cationic carbocyanine dye, Stains-all, in a spectrum of cartilages that vary in the sulfation position of their chondroitin sulfate. Cartilages from the rat and rabbit that are predominantly C4S stained magenta at pH 4.3, while the C6S-rich cartilage matrices from the regenerating rabbit ear and lamprey cranium stained blue. Embryonic chicken cartilages develop a gradient of magenta matrix with age, with increased concentration toward the articular surface. Both magenta and blue matrices were absent after pretreatment with chondroitinase ABC but were present after Streptomyces hyaluronidase digestion. The magenta staining was a property of the cartilage matrix as a whole, since isolated C4S and C6S stained blue. The differential staining was seen at pH 4.3, but not at pH 8.8, suggesting an interaction between the chondroitin sulfate and the adjacent tissue proteins.

The effect of fasting and time of day on the urinary excretion of chondroitin 4/6 sulphate, dermatan sulphate and four chondroitinase ABC resistant glycosaminoglycans

The present investigation confirmed a former report of a diurnal variation with an increased urinary excretion rate of total glycosaminoglycans in the daytime [4]. Fractionation showed that this increase was solely due to three electrophoretic fractions which resisted degradation with chondroitinase ABC. Fasting in the daytime had no influence on the increased excretion of one of these fractions, whereas it prevented the increased excretion of the other two (probably both heparan sulphates). The excretion rates of chondroitin 4/6 sulphate, dermatan sulphate and a fourth chondroitinase ABC resistant glycosaminoglycan (heparan sulphate) were uninfluenced by time of day and fasting. This was contrary to the excretion of hydroxyproline which decreased during the fasting period.