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PubMed1991

Sulfate homeostasis. IV. Probenecid-induced alterations of inorganic sulfate in rats.

Homeostasis of inorganic sulfate is maintained by the capacity-limited renal reabsorption of sulfate in the proximal tubule. The purpose of the present investigation was to determine if probenecid, the classical inhibitor of renal organic anion secretion, may affect sulfate renal clearance. Two groups of rats were administered in a randomized crossover design, an i.v. bolus dose (20.6 or 92.4 mg/kg) and 4-hr infusion (0.28 or 0.59 mg/min/kg) of probenecid or vehicle, and blood and urine samples were collected. At a steady-state serum concentration of 0.45 mM, probenecid had no significant effect on the serum concentrations or renal clearance of inorganic sulfate, whereas at a serum concentration of 1.4 mM, probenecid treatment caused a significant decrease in serum sulfate concentrations (0.57 +/- 0.11 vs 0.96 +/- 0.19 mM in controls, mean +/- SD, n = 6, P less than 0.001) due to an increase in the renal clearance of sulfate (3.88 +/- 1.18 vs 2.13 +/- 0.84 ml/min/kg in controls, P less than 0.01). The fraction of the filtered sulfate that was reabsorbed was significantly decreased (0.38 +/- 0.23, vs 0.74 +/- 0.09 in controls, P less than 0.01). Therefore, probenecid treatment results in the inhibition of the renal reabsorption of inorganic sulfate in rats in vivo.

Animals↗
PubMed1991

Sulfate homeostasis. III. Effect of chronic naproxen or sulindac treatment on inorganic sulfate disposition in arthritic patients with renal impairment.

The purpose of the present investigation was to examine the influence of chronic naproxen (500 mg twice daily) or sulindac (200 mg twice daily) therapy on the disposition of inorganic sulfate in arthritic subjects with impaired renal function. Subjects were studied during a control period (after a 7-day NSAID washout) and after 14 days of treatment with either naproxen or sulindac. During the control period subjects in this investigation exhibited higher serum sulfate concentrations and lower sulfate renal clearance values than reported for younger subjects with normal renal function. Treatment with either sulindac or naproxen significantly decreased creatinine clearance. Sulindac therapy also increased the serum sulfate concentration and decreased the clearance of sulfate; a similar trend was observed after naproxen therapy but the average change was smaller and not statistically significant. There were significant correlations between the creatinine and the sulfate clearances or serum concentrations. The glomerular filtration rate of inorganic sulfate was not altered by drug treatment and there was no impairment of reabsorption. The serum concentrations and renal clearance of other electrolytes (sodium, potassium, magnesium, calcium, phosphorus) were largely unaffected. Therefore, chronic treatment with naproxen or sulindac decreases the renal clearance of endogenous sulfate in humans: this appears to be a consequence of the decrement in renal function observed in subjects with preexisting mild renal impairment.

Aged↗
PubMed2006

Rat spongiotrophoblast-specific protein is predominantly a unique low sulfated chondroitin sulfate proteoglycan.

We have previously demonstrated that the human placenta contains a uniquely low sulfated extracellular aggrecan family chondroitin sulfate proteoglycan (CSPG). This CSPG is a major receptor for the adherence of Plasmodium falciparum-infected red blood cells (IRBCs) in placentas, causing pregnancy-specific malaria. However, it is not known whether such low sulfated CSPGs occur in placentas of other animals and, if so, whether IRBCs bind to those CSPGs. In this study, we show that rat placenta contains a uniquely low sulfated extracellular CSPG bearing chondroitin sulfate (CS) chains, which comprise only approximately 2% 4-sulfated and the remainder nonsulfated disaccharides. Surprisingly, the core protein of the rat placental CSPG, unlike that of the human placental CSPG, is a spongiotrophoblast-specific protein (SSP), which is expressed in a pregnancy stage-dependent manner. The majority of rat placental SSP is present in the CSPG form, and only approximately 10% occurs without CS chain substitution. Of the total SSP-CSPG in rat placenta, approximately 57% is modified with a single CS chain, and approximately 43% carries two CS chains. These data together with the previous finding on human placental CSPG suggest that the expression of low sulfated CSPG is a common feature of animal placentas. Our data also show that the unique species-specific difference in the biology of the rat and human placentas is reflected in the occurrence of completely different CSPG core protein types. Furthermore, the rat SSP-CSPG binds P. falciparum IRBCs in a CS chain-dependent manner. Since IRBCs have been reported to accumulate in the placentas of malaria parasite-infected rodents, our results have important implications for exploiting pregnant rats as a model for studying chondroitin 4-sulfate-based therapeutics for human placental malaria.

Animals↗
PubMed1998

Substrate specificity of human monoamine (M)-form phenol sulfotransferase: preparation and analysis of Dopa 3-O-sulfate and Dopa 4-O-sulfate.

Upon two-dimensional thin-layer separation, the sulfated L-3, 4-dihydroxyphenylalanine (L-DopaS) generated enzymatically was found to co-migrate with only one of the two ninhydrin-stained spots corresponding to the two sulfated forms (3-O-sulfate and 4-O-sulfate) of synthetic L-DopaS. To clarify precisely the identity of the enzymatically generated L-DopaS, the two sulfated forms of synthetic L-DopaS were separated and purified using high performance liquid chromatography. Purified L-Dopa 3-O-sulfate and L-Dopa 4-O-sulfate were identified by 1H-nuclear magnetic resonance (NMR) spectrometry and used as standards in the analysis of the L-DopaS generated during metabolic labeling of HepG2 human hepatoma cells or enzymatic assay using recombinant human monoamine (M)-form phenol sulfotransferase. The results obtained demonstrated unequivocally the generation of L-Dopa 3-O-sulfate, indicating the specificity of the M-form phenol sulfotransferase being for the meta-hydroxyl group of L-Dopa.

Arylsulfotransferase↗
PubMed1990

Chondroitin sulfates in developing mouse tooth germs. An immunohistochemical study with monoclonal antibodies against chondroitin-4 and chondroitin-6 sulfates.

The role of glycosaminoglycans and proteoglycans during ontogenesis is not known. The developing tooth offers a potentially important model for studies of structure-function relationships. In this study, we have analysed the temproal and spatial expression of chondroitins of differing sulfation patterns in embryonic molars and incisors. For this purpose, we have used monoclonal antibodies (Mabs) specific for unsulfated, 4-sulfated, and 6-sulfated forms of chondroitin in conjunction with indirect immunofluorescence or immunoperoxidase labeling. Unsulfated chondroitin was not detected in embryonic teeth. Chondroitin 4- and chondroitin 6-sulfates were present in the stellate reticulum but otherwise they were confined to the dental mesenchyme. The 3B3 and MC21C-epitope, which are markers of 6-sulfated chondroitin, were uniformly distributed in the dental mesenchyme during the bud stage; they disappeared from the dental papilla of the cusps and of the anterior region of the incisor as development proceeded. These epitopes were absent from the basement membrane and from the predentin. In the odontoblastic cell lineage, the 3B3 and MC21C-epitopes were detected only between preodontoblasts at an early stage of differentiation. The monoclonal antibody 2B6 served as a probe to localize chondroitin 4-sulfate. This glycosaminoglycan was detected as early as the dental lamina stage but its expression was restricted to the basement membrane of the teeth until the late bell stage. After the onset of cusp formation, strong staining was also observed over the occlusal region of the dental papilla while the cervical region of the dental papilla remained 2B6-negative. Incisors at the bell stage exhibited a decreasing gradient of immunostaining by 2B6 from their anterior region to their posterior end. The extracellular matrix surrounding preodontoblasts reacted with 2B6 and the predentin, produced by the odontoblasts, was also intensely labeled with this antibody. Comparison between immunostaining with 3B3 and 2B6, on consecutive sections revealed a mutually exclusive pattern of distribution of the corresponding epitopes during odontogenesis. Furthermore, in the continuously growing incisor, a striking positive correlation was found between the immunostaining patterns produced by 3B3 and MC21C and the mitotic indices along the anterior-posterior axis of the tooth. Hence, sulfation of chondroitin seems developmentally regulated. We postulate that changes in the sulfation pattern of chondroitin might play a role in ontogenesis by locally altering the functional properties of the extracellular matrix.

Animals↗
PubMed2004

Phosphomannopentaose sulfate (PI-88): heparan sulfate mimetic with clinical potential in multiple vascular pathologies.

The sulfated oligosaccharide PI-88 is a potent antiangiogenic, antitumor and anti-metastatic agent derived from yeast. It is primarily composed of sulfated phosphomannopentaose and phosphomannotetraose oligosaccharide units and is presently under evaluation in Phase II clinical trials for anticancer efficacy. PI-88 inhibits the heparan sulfate-degrading enzyme heparanase, exhibits antiangiogenic activity and has anticoagulant properties mediated by heparin cofactor II. It also inhibits vascular smooth muscle cell proliferation, kinase signalling and arterial intimal thickening following balloon injury. Many heparan sulfate-binding growth factors require heparan sulfate as a co-receptor in order to effectively deliver growth signals to cells. Thus, the antiangiogenic and antirestenotic activity of PI-88 may be at least partially due to this highly sulfated oligosaccharide competing with the interaction of growth factors, such as FGF-2 and VEGF, with cell surface heparan sulfate. This heparan sulfate mimetic has, therefore, multiple functions and therapeutic potential in a variety of vascular disorders.

Angiogenesis Inhibitors↗
PubMed1983

Monohydroxy bile salt sulfates: tauro-3 beta-hydroxy-5-cholenoate-3-sulfate induces intrahepatic cholestasis in rats.

The biologic effects of sulfation of tauro-3 beta-hydroxy-5-cholenoate and of taurolithocholate were compared. Equimolar amounts (100 nmol/min X 100 g body wt) of the following were administered intravenously to male Sprague-Dawley rats over a 180-min period: taurolithocholate, [14C]taurolithocholate-3-sulfate, tauro-3 beta-hydroxy-5-cholenoate, [14C]tauro-3 beta-hydroxy-5-cholenoate-3-sulfate, its combination with taurocholate, and a saline-albumin solution (control). Sulfation of taurolithocholate and of tauro-3 beta-hydroxy-5-cholenoate only prevented the cholestatic effect of the former. Bile flow during infusion of [14C]tauro-3 beta-hydroxy-5-cholenoate-3-sulfate was reduced by 80% at the end of the experiment. A dose-dependent bile flow reduction was demonstrated. Recovery of the administered bile acid was 3% in urine, 13% in serum, 23% in the liver tissue, and 52% in bile, respectively. Excretion of biliary cholesterol and phospholipids was significantly reduced during the first hour of infusion. Coadministration of taurocholate abolished the cholestatic effect and enhanced the renal excretion of the sulfated bile salt. These data suggest that (a) the cholestatic effect of tauro-3 beta-hydroxy-5-cholenoate-3-sulfate is comparable with or may even exceed the effect of taurolithocholate and (b) although sulfation renders some bile salts more water soluble, it does not prevent the cholestatic effect of all monohydroxy bile salts.

Animals↗
PubMed1994

Tagging secretory and membrane proteins with a tyrosine sulfation site. Tyrosine sulfation precedes galactosylation and sialylation in COS-7 cells.

Sulfation of proteins on tyrosines is a late Golgi modification that can be used to label proteins with [35S]sulfate for the analysis of post-Golgi transport. To extend the use of this modification to proteins not naturally sulfated, we fused a tyrosine sulfation site, the carboxyl-terminal nonapeptide of cholecystokinin precursor, to the carboxyl terminus of two normally unsulfated proteins: alpha 1-proteinase inhibitor, a secretory protein, and subunit H1 of the asialoglycoprotein receptor; a type II membrane protein. The tagged proteins were efficiently sulfated in transfected COS-7 and Madin-Darby canine kidney cells. Specifically in COS-7 cells, the proteins were sulfated before they were galactosylated and sialylated and were converted to the mature forms with a half-time of approximately 2-3 min. This is in contrast to other cell types in which tyrosine sulfation was found to be virtually the last modification of the Golgi apparatus. Our results suggest that tyrosine sulfation occurs before the trans-Golgi in transfected COS-7 cells.

Amino Acid Sequence↗
PubMed1998

Structure of heparan sulfate: identification of variable and constant oligosaccharide domains in eight heparan sulfates of different origins.

The use of specific enzymes (heparinase and heparitinases from Flavobacterium heparinum, endoglucuronidase, alphaN-acetylglucosaminidase and beta-glucuronidase from the mollusc Anomalocardia brasiliana) and chemical methods (nitrous acid degradation, hydrazine N-deacetylation and borohydride reduction), led to the proposal of the total sequence of a heparan sulfate derived from bovine pancreas and partial sequences of heparan sulfates from different origins (bovine: lung, liver, brain; hog: liver, brain; rabbit liver; dog liver). It was shown that all the heparan sulfates contain common structural features such as: a N-acetylated and a N-sulfated domain made of glucuronic acid-containing disaccharides and a more sulfated region made of iduronic acid-containing disaccharides. Separating the two domains a peculiar tetrasaccharide made of GlcNAc-(alpha1-4)-IdoUA-(alpha1-4)-GlcNS-(alpha1-4)-IdoUA was identified in all the heparan sulfates analyzed. It was also shown that the non-reducing ends of the heparan sulfates contain the monosaccharides glucosamine N-sulfate and/or glucosamine 2,6 disulfate.

Animals↗
PubMed1978

Sulfated glycosaminoglycans of cells grown in culture: dermatan sulfate disappearance in successive fibroblast subcultures.

Sulfated glycosaminoglycan content of primary cultures of guinea pig embryo fibroblast in reported. It is shown that changes of sulfated glycosaminoglycans occur in successive subcultures: 1) disappearance of dermatan sulfate and 2) a slight increase in the proportion of heparitin sulfate. The sulfated glycosaminoglycan composition of the mammalian cell established lines: VERO, SIRK, Hep-2, MK-2, BGM, IB-RS-11 (S6) and 3T6 is also reported. It is shown that chondroitin sulfate AC and/or heparitin sulfate are the main glycosaminoglycans of the established cell lines (except 3T6). A possible role of these glycosaminoglycans in cell biology is discussed.

Cell Line↗
PubMed2002

Enzymatic synthesis of chondroitin sulfate E by N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase purified from squid cartilage.

Chondroitin sulfate E (CS-E), a chondroitin sulfate isomer containing GlcAbeta1-3GalNAc(4,6-SO(4)) repeating unit, was found in various mammalian cells in addition to squid cartilage and is predicted to have several physiological functions in various mammalian systems such as mast cell maturation, regulation of procoagulant activity of monocytes, and binding to midkine or chemokines. To clarify the physiological functions of GalNAc(4,6-SO(4)) repeating unit, preparation of CS-E with a defined content of GalNAc(4,6-SO(4)) residues is important. We report here the in vitro synthesis of CS-E from chondrotin sulfate A (CS-A) by the purified squid N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST) which catalyzed transfer of sulfate from 3(')-phosphoadenosine-5(')-phosphosulfate to position 6 of GalNAc(4SO(4)) residues of CS-A and dermatan sulfate (DS). When CS-A was used as an acceptor, about half of GalNAc(4SO(4)) residues, on average, were converted to GalNAc(4,6-SO(4)) residues. Anion exchange chromatography of the CS-E synthesized in vitro showed marked heterogeneity in negative charge; the proportion of GalNAc(4,6-SO(4)) in the most negative fraction exceeded 70% of the total sulfated repeating units. GalNAc4S-6ST also catalyzed the synthesis of oversulfated DS with GalNAc(4,6-SO(4)) residues from DS. Squid GalNAc4S-6ST thus should provide a useful tool for preparing CS-E and oversulfated DS with a defined proportion of GalNAc(4,6-SO(4)) residues.

Animals↗
PubMed2002

Molecular cloning and expression of human chondroitin N-acetylgalactosaminyltransferase: the key enzyme for chain initiation and elongation of chondroitin/dermatan sulfate on the protein linkage region tetrasaccharide shared by heparin/heparan sulfate.

Based on sequence homology with the recently cloned human chondroitin synthase, we identified a novel beta1,4-N-acetylgalactosaminyltransferase, which consisted of 532 amino acids with a type II transmembrane protein topology. The amino acid sequence displayed 27% identity to that of human chondroitin synthase. The expression of a soluble form of the protein in COS-1 cells produced an active enzyme, which transferred beta1,4-N-acetylgalactosamine (GalNAc) from UDP-[(3)H]GalNAc not only to a polymer chondroitin representing growing chondroitin chains (beta-GalNAc transferase II activity) but also to GlcUAbeta1--3Galbeta1-O-C(2)H(4)NH-benzyloxycarbonyl, a synthetic substrate for beta-GalNAc transferase I that transfers the first GalNAc to the core tetrasaccharide in the protein linkage region of chondroitin sulfate. Hence, the enzyme is involved in the biosynthetic initiation and elongation of chondroitin sulfate and is the key enzyme responsible for the selective chain assembly of chondroitin/dermatan sulfate on the linkage region tetrasaccharide common to various proteoglycans containing chondroitin/dermatan sulfate or heparin/heparan sulfate chains. The coding region of this enzyme was divided into seven discrete exons and localized to chromosome 8. Northern blot analysis revealed that the chondroitin GalNAc transferase gene exhibited a ubiquitous but markedly differential expression in human tissues and that the expression pattern was similar to that of chondroitin synthase. Thus, more than two distinct enzymes forming the novel gene family are required for chain initiation and elongation in chondroitin/dermatan sulfate as in the biosynthesis of heparin/heparan sulfate.

Acetylgalactosamine↗
PubMed1993

Regulation of biosynthesis of the basic fibroblast growth factor binding domains of heparan sulfate by heparan sulfate-N-deacetylase/N-sulfotransferase expression.

Heparan sulfate-N-deacetylase/N-sulfotransferase catalyzes both the N-deacetylation and N-sulfation reactions that initiate the modification of the oligosaccharide backbone of heparan sulfate (HS). The glycosaminoglycan polymer appears to modulate the activity of growth factors by mediating their initial binding. To understand how the biosynthesis of these binding sites is regulated, a rat liver-derived cDNA encoding the above activities was overexpressed in a COS cell mutant (CM-15) that has reduced levels of the enzyme and binds poorly to immobilized basic fibroblast growth factor (bFGF). This resulted in increased synthesis of sulfated blocks of decasaccharide size or longer. These blocks exhibited high affinity binding to bFGF and contained a high content of 2-O-sulfated iduronate and at least five consecutive N-sulfated disaccharides. An increase in the synthesis of these high affinity blocks was not seen in transfected wild-type COS cells even though they showed a 4-fold increase of both enzyme activities, suggesting that once sufficient levels of highly sulfated blocks of saccharides with high affinity for bFGF are attained, no further synthesis of these domains occurs.

Amidohydrolases↗
PubMed2001

Sulfate Reduction Dynamics and Enumeration of Sulfate-Reducing Bacteria in Hypersaline Sediments of the Great Salt Lake (Utah, USA).

Bacterial sulfate reduction activity (SRA) was measured in surface sediments and slurries from three sites in the Great Salt Lake (Utah, USA) using radiolabeled 35S-sulfate. High rates of sulfate reduction (363 +/- 103 and 6,131 +/- 835 nmol cm-3 d-1) were measured at two sites in the moderately hypersaline southern arm of the lake, whereas significantly lower rates (32 +/- 9 nmol cm-3 d-1) were measured in the extremely hypersaline northern arm. Bacterial sulfate reduction was strongly affected by salinity and showed an optimum around 5-6% NaCl in the southern arm and an optimum of around 12% NaCl in the more hypersaline northern arm of the lake. High densities of sulfate-reducing bacteria (SRB) ranging from 2.2 x 107 to 6.7 x 108 cells cm-3 were determined by a newly developed tracer MPN-technique (T-MPN) employing sediment media and 35S-sulfate. Calculation of specific sulfate reduction rates yielded values comparable to those obtained in pure cultures of SRB. However, when using a conventional MPN technique with synthetic media containing high amounts of Fe(II), the numbers of SRB were underestimated by 1-4 orders of magnitude as compared to the T-MPN method. Our results suggest that high densities of slightly to moderately halophilic and extremely halotolerant SRB are responsible for the high rates of sulfate reduction measured in Great Salt Lake sediments.

Journal Article↗
PubMed1991

Sulfation of some chemically-modified heparins. Formation of a 3-sulfate analog of heparin.

A modified form of heparin containing residues of nonsulfated alpha-L-idopyranosyluronic acid (7) in place of the normal 2-sulfate (1) was sulfated with sulfur trioxide-trimethylamine in dimethylformamide at 0 and 25 degrees. Examination of the reaction products by n.m.r. spectroscopy showed that sulfation occurred selectively at C-3 of residue 7, to give a new polymer that may be described as a 3-sulfate analog of heparin. A slower substitution reaction led subsequently to sulfation at C-3 of 2-deoxy-2-sulfamino-alpha-D-glucopyranosyl 6-sulfate residues (2), although this was accompanied by partial N-desulfation of 2. An analogous pattern of O-sulfation-N-desulfation was observed for the residues of 2 in two other modified heparins, one containing residues of 2,3-anhydro-alpha-L-gulopyranosyluronic acid and the other residues of alpha-L-galactopyranosyluronic acid, in place of residues of 1. The galacto diastereomer exhibited relatively low regioselectivity, as it was found to be sulfated at C-2 or C-2.3, or both. Selective resulfation of free amino groups gave the products that were examined for anticoagulant activity and susceptibility to enzymolysis by heparinase. Antithrombin-binding affinity measurements were also carried out. Although none of the materials had significant anti-Xa activity, nor were they affected by heparinase, their patterns of binding to antithrombinagarose were not dissimilar to that of heparin.

Anticoagulants↗
PubMed1986

Sulfated LH subunits and a tyrosine-sulfated secretory protein (secretogranin II) in female rat adenohypophyses: changes with age and stimulation of release by LHRH.

Sulfated proteins are present in adenohypophyseal secretory granules but their function and structure are still largely unknown. We studied these proteins in homogenates from cow and rat adenohypophyses labeled in vitro with [35S]sulfate, by one-dimensional and two-dimensional polyacrylamide gel electrophoresis followed by fluorography. We found that the heterogeneous neutral-alkaline sulfated components of approximately 22-20 kDa and approximately 20-18 kDa previously described correspond to lutropin alpha and beta subunits sulfated on carbohydrates. During development sulfated lutropin subunits were found at highest levels in anterior pituitary glands of 14-day-old female rats. Secretogranin II, an acidic tyrosine-sulfated secretory protein, whose presence in granules of gonadotrophs has been recently described, had a similar distribution during development. In the 14-day-old female rat glands luteinizing hormone-releasing hormone stimulated the in vitro release of both sulfated lutropin subunits and secretogranin II. This finding further suggests that secretogranin II might be involved in the packaging of the gonadotrophin. Immature female rat adenohypophyses provide a useful approach for studying sulfation, both on carbohydrate and on tyrosine residues, of secretory proteins.

Aging↗
PubMed2006

Simultaneous determination of neomycin sulfate and polymyxin B sulfate by capillary electrophoresis with indirect UV detection.

A simple and rapid capillary electrophoresis method, with indirect UV detection, for the simultaneous determination of neomycin sulfate and polymyxin B sulfate in pharmaceutical formulations was developed. Critical parameters such as pH, buffer composition and concentration, voltage and injection time have been studied to evaluate, how they affect responses, such as resolution and migration times. Separation was performed on a fused silica capillary with 50 microm i.d. and 27 cm total length at an applied voltage of 6 kV with a 15 mM phosphate run buffer (pH 5.0) containing 40 mM N-(4-hydroxy-phenyl)acetamide and 50 mM tetradecylammonium bromide (TTAB). The detection wavelength was set at 280 nm. Quantitative analysis was validated by testing the reproducibility of the method, giving a relative standard deviation less than 0.4 and 2.4% for the repeatability of migration time and corrected peak area, respectively. Accuracy was tested by spiking eye-ear formulations with standards and the recoveries of neomycin sulfate and polymyxin B sulfate were found to be between 97.44-103.18% and 96.85-101.68%, respectively. Linearity of neomycin sulfate and polymyxin B sulfate were obtained in the ranges of 17-682 and 24-608 microg/mL, respectively, with r(2) values above 0.999. The established TLC-densitometric method was applied to evaluate the proposed CE method, and comparable results were obtained by using CE with much shorter analysis time and a small quantity of solvents consumed. The developed method is also the first report on the simultaneous determination of neomycin sulfate and polymyxin B sulfate in pharmaceutical preparations by CE.

Anti-Bacterial Agents↗
PubMed1999

Structure of the sulfated alpha-L-fucan from the egg jelly coat of the sea urchin Strongylocentrotus franciscanus: patterns of preferential 2-O- and 4-O-sulfation determine sperm cell recognition.

The egg jelly coats of sea urchins contains sulfated polysaccharides responsible for inducing the sperm acrosome reaction which is an obligatory event for sperm binding to, and fusion with, the egg. Here, we extend our study to the sea urchin Strongylocentrotus franciscanus. The egg jelly of this species contains a homofucan composed of 2- O -sulfated, 3-linked units which is the simplest structure ever reported for a sulfated fucan. This polysaccharide was compared with other sulfated alpha-L-fucans as inducers of acrosome reaction in conspecific and heterospecific sperm. Although all these fucans are linear polymers composed of 3-linked alpha-L-fucopyranosyl units, they differ in the proportions of 2-O- and 4-O-sulfation. The reactivity of the sperm of each species is more sensitive to the egg jelly sulfated fucan found in their own species. The reactivity of the sperm does not correlate with the charge density of the fucan, but with the proportion of 2-O- and 4-O-sulfation. The pattern of sulfation may be an important feature for recognition of fucans by the sperm receptor contributing to the species-specificity of fertilization.

Acrosome Reaction↗