RESUMO
The parotoid gland of bufonids is characterized as a specialized integument region, formed by different gland types. The secretion elaborated by the largest glandular alveoli has been related to animal chemical defense and is constituted by granular protein content, associated with a basophilic and alcianophilic material with features of glycoconjugates. This study aimed to identify and characterize the glycoconjugates in the secretion of the largest granular gland of the parotoid gland of Rinella icterica by histochemical and immunohistochemical techniques at light microscopy, biochemical methods, and nuclear magnetic resonance spectroscopy. Our results showed that the glycoconjugate content contains a mixture of chondroitin6sulfate (C6S) and chondroitin-non-sulfate (C0S). Thus, chondroitin sulfate probably plays an important role in gland physiology, probably protecting the protein content while inside the secretory portion.
Assuntos
Acetilgalactosamina/química , Bufonidae/metabolismo , Sulfatos de Condroitina/química , Ácido Glucurônico/química , Glicoconjugados/química , Glândula Parótida/química , Acetilgalactosamina/isolamento & purificação , Animais , Brasil , Bufonidae/anatomia & histologia , Sequência de Carboidratos , Sulfatos de Condroitina/isolamento & purificação , Ácido Glucurônico/isolamento & purificação , Glicoconjugados/isolamento & purificação , Masculino , Glândula Parótida/anatomia & histologia , Glândula Parótida/fisiologiaRESUMO
Biological functions of nuclear proteins are regulated by post-translational modifications (PTMs) that modulate gene expression and cellular physiology. However, the role of O-linked glycosylation (O-GalNAc) as a PTM of nuclear proteins in the human cell has not been previously reported. Here, we examined in detail the initiation of O-GalNAc glycan biosynthesis, representing a novel PTM of nuclear proteins in the nucleus of human cells, with an emphasis on HeLa cells. Using soluble nuclear fractions from purified nuclei, enzymatic assays, fluorescence microscopy, affinity chromatography, MS, and FRET analyses, we identified all factors required for biosynthesis of O-GalNAc glycans in nuclei: the donor substrate (UDP-GalNAc), nuclear polypeptide GalNAc -transferase activity, and a GalNAc transferase (polypeptide GalNAc-T3). Moreover, we identified O-GalNAc glycosylated proteins in the nucleus and present solid evidence for O-GalNAc glycan synthesis in this organelle. The demonstration of O-GalNAc glycosylation of nuclear proteins in mammalian cells reported here has important implications for cell and chemical biology.
Assuntos
Acetilgalactosamina/biossíntese , Acetilgalactosamina/química , Núcleo Celular/metabolismo , Polissacarídeos/química , Transporte Ativo do Núcleo Celular , Linhagem Celular Tumoral , Glicosilação , Humanos , Lamina Tipo B/metabolismo , N-Acetilgalactosaminiltransferases/metabolismo , Polipeptídeo N-AcetilgalactosaminiltransferaseRESUMO
Lectins are proteins able to interact specifically and reversibly with carbohydrates. They are present in all living beings, particularly in legume seeds, which have many biological functions. The aim of this study was to isolate, characterize and verify antioxidant, anti-hemolytic, antitumor and gastroprotective activities in a lectin present in seeds of Phaseolus lunatus L. var. cascavel (PLUN). The isolation of lectin was performed by size exclusion chromatography on Sephadex G-100, which was isolated from a protein capable of agglutinating only human erythrocytes type A, being this the only inhibited haemagglutination n-acetyl-d-galactosamine. Its weight was estimated by PAGE is 128kDa. The lectin is thermostable up to 80°C and is active between pH 2-11. As 8M urea was able to denature the lectin. PLUN is a glycoprotein consisting of 2% carbohydrate and has antioxidant action with ascorbic acid equivalent antioxidant capacity (µMAA/g) of 418.20, 326 and 82.9 for total antioxidant activity, ABTS radical capture and capture of DPPH radical, respectively. The lectin has antitumor activity against melanoma derived cells at doses of 100 and 50mg/ml, reducing up to 83% tumor cells, and gastroprotective action, reducing up to 63% damaged area of ââthe stomach induced by ethanol.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Antioxidantes/farmacologia , Fármacos Gastrointestinais/farmacologia , Phaseolus/química , Lectinas de Plantas/farmacologia , Úlcera Gástrica/tratamento farmacológico , Acetilgalactosamina/química , Animais , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Antioxidantes/química , Antioxidantes/isolamento & purificação , Benzotiazóis/antagonistas & inibidores , Benzotiazóis/química , Compostos de Bifenilo/antagonistas & inibidores , Compostos de Bifenilo/química , Linhagem Celular Tumoral , Eritrócitos/efeitos dos fármacos , Etanol , Fármacos Gastrointestinais/química , Fármacos Gastrointestinais/isolamento & purificação , Testes de Hemaglutinação , Humanos , Masculino , Camundongos , Peso Molecular , Picratos/antagonistas & inibidores , Picratos/química , Lectinas de Plantas/química , Lectinas de Plantas/isolamento & purificação , Desnaturação Proteica , Sementes/química , Extração em Fase Sólida/métodos , Estômago/efeitos dos fármacos , Estômago/patologia , Úlcera Gástrica/induzido quimicamente , Úlcera Gástrica/patologia , Ácidos Sulfônicos/antagonistas & inibidores , Ácidos Sulfônicos/química , Ureia/químicaRESUMO
Plant lectins have been studied as histological markers and promising antineoplastic molecules for a long time, and structural characterization of different lectins bound to specific cancer epitopes has been carried out successfully. The crystal structures of Vatairea macrocarpa (VML) seed lectin in complex with GalNAc-α-O-Ser (Tn antigen) and GalNAc have been determined at the resolution of 1.4Å and 1.7Å, respectively. Molecular docking analysis of this new structure and other Tn-binding legume lectins to O-mucin fragments differently decorated with this antigen provides a comparative binding profile among these proteins, stressing that subtle alterations that may not influence monosaccharide binding can, nonetheless, directly impact the ability of these lectins to recognize naturally occurring antigens. In addition to the specific biological effects of VML, the structural and binding similarities between it and other lectins commonly used as histological markers (e.g., VVLB4 and SBA) strongly suggest VML as a candidate tool for cancer research.
Assuntos
Antígenos Glicosídicos Associados a Tumores/química , Antígenos Glicosídicos Associados a Tumores/metabolismo , Fabaceae/química , Lectinas de Plantas/química , Lectinas de Plantas/metabolismo , Acetilgalactosamina/química , Sítios de Ligação , Cristalografia por Raios X , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Simulação de Acoplamento Molecular , Mucina-2/química , Homologia Estrutural de Proteína , TermodinâmicaRESUMO
Lectins are carbohydrate-binding proteins that recognize and modulate physiological activities and have been used as a toll for detection and identification of biomolecules, and therapy of diseases. In this study we have isolated a lectin present in the latex of Euphorbia tirucalli, and named it Eutirucallin. The latex protein extract was subjected to ion exchange chromatography and showed two peaks with haemagglutinating activity. Polypeptides of 32 kDa protein extract strongly interacted with immobilized galactose (α-lactose > D-N-acetylgalactosamine). The Eutirucallin was obtained with a yield of 5.6% using the α-lactose column. The lectin domain has 32 kDa subunits and at least two of which are joined by disulfide bridges. The agglutinating capacity for human erythrocytes A(+), B(+) and O(+) is inhibited by D-galactose. The haemagglutinating activity of Eutirucallin was independent of Ca(2+) and maintained until the temperature of 55°C. Eutirucallin presented biological activities such as neutrophils recruitment and cytokine prodution by macrophages. The analysis of the trypsin-digested Eutirucallin by ms/ms in ESI-Q-TOFF resulted in nine peptides similar to type 2 ribosome-inactivating protein (type-2 RIP). It's partial sequence showed a similarity of 67.4 - 83.1% for the lectin domain of type-2 RIP [Ricin and Abrin (83.1%), Viscumin, Ebulin, Pulchellin, Cinnamomin, Volkensin and type-2 RIP Iris hollandica]. Our data suggest that Eutirucallin is a new member of type 2 ribosome-inactivating protein and presents biotechnological potential.
Assuntos
Euphorbia/química , Inflamação/induzido quimicamente , Látex/química , Extratos Vegetais/química , Lectinas de Plantas/química , Acetilgalactosamina/química , Cálcio/química , Dissulfetos/química , Eritrócitos/efeitos dos fármacos , Galactose/química , Humanos , Lactose/química , Lectinas/química , Macrófagos/efeitos dos fármacos , Peptídeos/química , Estrutura Terciária de Proteína , Ribossomos/química , Espectrometria de Massas por Ionização por Electrospray , TemperaturaRESUMO
This work addresses the synthesis and biological evaluation of glycosyl diketopiperazines (DKPs) cyclo[Asp-(αGalNAc)Ser] 3 and cyclo[Asp-(αGalNAc)Thr] 4 for the development of novel anti-trypanosomal agents and Trypanosoma cruzi trans-sialidase (TcTS) inhibitors. The target compounds were synthetized by coupling reactions between glycosyl amino acids αGalNAc-Ser 7 or αGalNAc-Thr 8 and the amino acid (O-tBu)-Asp 17, followed by one-pot deprotection-cyclisation reaction in the presence of 20% piperidine in DMF. The protected glycosyl amino acid intermediates 7 and 8 were, in turn, obtained by α-selective, HgBr2-catalysed glycosylation reactions of Fmoc-Ser/Thr benzyl esters 12/14 with αGalN3Cl 11, being, subsequently, fully deprotected for comparative biological assays. The DKPs 3 and 4 showed relevant anti-trypanosomal effects (IC50 282-124 µM), whereas glycosyl amino acids 1 and 2 showed better TcTS inhibition (57-79%) than the corresponding DKPs (13-25%).
Assuntos
Acetilgalactosamina/química , Acetilgalactosamina/farmacologia , Dicetopiperazinas/química , Dicetopiperazinas/farmacologia , Tripanossomicidas/química , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Acetilgalactosamina/síntese química , Animais , Linhagem Celular , Células Cultivadas , Doença de Chagas/tratamento farmacológico , Doença de Chagas/parasitologia , Dicetopiperazinas/síntese química , Glicoproteínas/antagonistas & inibidores , Glicoproteínas/metabolismo , Glicosilação , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Mucinas/química , Mucinas/farmacologia , Neuraminidase/antagonistas & inibidores , Neuraminidase/metabolismo , Tripanossomicidas/síntese química , Trypanosoma cruzi/enzimologiaRESUMO
Lectins are able to recognize specific carbohydrate structures through their carbohydrate recognition domain (CRD). The lectin from the mushroom Agaricus bisporus (ABL) has the remarkable ability of selectively recognizing the TF-antigen, composed of Galß1-3GalNAc, Ser/Thr linked to proteins, specifically exposed in neoplastic tissues. Strikingly, the recently solved crystal structure of tetrameric ABL in the presence of TF-antigen and other carbohydrates showed that each monomer has two CRDs, each being able to bind specifically to different monosaccharides that differ only in the configuration of a single hydroxyl, like N-acetyl-d-galactosamine (GalNAc) and N-acetyl-d-glucosamine (GlcNAc). Understanding how lectin CRDs bind and discriminate mono and/or (poly)-saccharides is an important issue in glycobiology, with potential impact in the design of better and selective lectin inhibitors with potential therapeutic properties. In this work, and based on the unusual monosaccharide epimeric specificity of the ABL CRDs, we have performed molecular dynamics simulations of the natural (crystallographic) and inverted (changing GalNAc for GlcNAc and vice-versa) ABL-monosaccharide complexes in order to understand the selective ligand recognition properties of each CRD. We also performed a detailed analysis of the CRD local solvent structure, using previously developed methodology, and related it with the recognition mechanism. Our results provide a detailed picture of each ABL CRD specificity, allowing a better understanding of the carbohydrate selective recognition process in this particular lectin.
Assuntos
Lectinas/química , Acetilgalactosamina/química , Acetilglucosamina/química , Agaricus/química , Agaricus/metabolismo , Antígenos Glicosídicos Associados a Tumores/metabolismo , Sítios de Ligação , Configuração de Carboidratos , Ligação de Hidrogênio , Lectinas/metabolismo , Simulação de Dinâmica Molecular , Ligação Proteica , TermodinâmicaRESUMO
Lectins have been classified into a structurally diverse group of proteins that bind carbohydrates and glycoconjugates with high specificity. They are extremely useful molecules in the characterization of saccharides, as drug delivery mediators, and even as cellular surface makers. In this study, we present camptosemin, a new lectin from Camptosema ellipticum. It was characterized as an N-acetyl-D-galactosamine-binding homo-tetrameric lectin, with a molecular weight around 26 kDa/monomers. The monomers were stable over a wide range of pH values and exhibited pH-dependent oligomerization. Camptosemin promoted adhesion of breast cancer cells and hemagglutination, and both activities were inhibited by its binding of sugar. The stability and unfolding/folding behavior of this lectin was characterized using fluorescence and far-UV circular dichroism spectroscopies. The results indicate that chemical unfolding of camptosemin proceeds as a two-state monomer-tetramer process. In addition, small-angle X-ray scattering shows that camptosemin behaves as a soluble and stable homo-tetramer molecule in solution.
Assuntos
Fabaceae/química , Lectinas de Plantas/química , Acetilgalactosamina/química , Neoplasias da Mama/química , Carboidratos/química , Adesão Celular , Linhagem Celular Tumoral , Dicroísmo Circular , Feminino , Gleiquênias , Hemaglutinação , Humanos , Concentração de Íons de Hidrogênio , Peso Molecular , Lectinas de Plantas/genética , Lectinas de Plantas/isolamento & purificação , Ligação Proteica , Conformação Proteica , Multimerização Proteica , Estabilidade Proteica , Espalhamento a Baixo Ângulo , Homologia de Sequência de Aminoácidos , Espectrometria de Fluorescência , Raios Ultravioleta , Difração de Raios XRESUMO
Amaranthus leucocarpus syn. hypochondriacus lectin (ALL) has been shown to be specific for N-acetyl-D-galactosamine (GalNAc). In this work, we determined a value of 1.0 x 10(-2) M for the association constant of ALL for GalNAc, calculated using fluorescence spectroscopy assays. Using neoglycopeptides obtained by in vitro O-glycosylation, we determined the main features of O-glycopeptides recognized by ALL using molecular dynamics simulations, capillary electrophoresis, and ELISA. Neo-glycopeptides were obtained by in vitro O-glycosylation reaction using microsomal preparations of murine thymocytes, human gastric fundus and colonic mucosa. ELISA assays were performed with peroxidase-labeled murine monoclonal IgG2, kappa light chain (5D4) antibodies against ALL. Among the in vitro neoglycopeptides, only those of TTSAPTTS containing GalNAc at Thr in #2 and #6 reacted with ALL. Neither the TTSAPTTS glycopeptide, containing a unique GalNAc residue at Thr in #2, nor others (with more than two GalNAc residues) interacted with the lectin. Computational docking assays of the lower energy conformers for interactions between glycopeptides and lectins confirmed that ALL recognized GalNAc residues when they are spaced out in glycan structures, whereas GalNAc residues arranged in clusters prevented interaction with the lectin, indicating that ALL is specific for a special GalNAc-containing motif found in different O-glycoproteins.
Assuntos
Glicopeptídeos/química , Glicoproteínas/química , Lectinas de Plantas/química , Acetilgalactosamina/química , Amaranthus , Sequência de Aminoácidos , Animais , Eletroforese Capilar , Feminino , Glicopeptídeos/metabolismo , Glicosilação , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Microssomos/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Conformação Proteica , Espectrometria de Fluorescência , Timo/metabolismoRESUMO
Fucosylated chondroitin sulfate is a glycosaminoglycan from sea cucumber, made up of alternating beta-D-glucuronic acid and N-acetyl-beta-D-galactosamine units, like mammalian chondroitin sulfate. But the beta-D-glucuronic acid residues have branches of sulfated fucose, which confer high anticoagulant and antithrombotic properties on this compound. We have now compared the anticoagulant, bleeding and antithrombotic effects of this fucosylated chondroitin sulfate and its carboxyl-reduced derivative. Both compounds have similar anticoagulant action, mostly due to acceleration of thrombin inhibition in the presence of heparin cofactor II. The native glycosaminoglycan shows a correlation among anticoagulant, bleeding and antithrombotic effects. Inhibition of thrombosis in an arterio-venous shunt occurs at low doses, which are almost ineffective in modifying the anticoagulant activity of plasma. In a venous experimental model, on the contrary, antithrombotic activity requires high doses and occurs concomitantly with an increase in the anticoagulant activity of plasma. The action of fucosylated chondroitin sulfate on thrombosis is apparently unrelated to its effect on platelet aggregation. The carboxyl-reduced derivative of fucosylated chondroitin sulfate prevented thrombosis in the arterio-venous shunt, but not in the venous experimental model. This derivative did not increase bleeding, in spite of its potent anticoagulant activity. Therefore, our results reveal a dissociation of the anticoagulant, bleeding and antithrombotic effects of the glycosaminoglycan. Furthermore, we demonstrate that a polysaccharide may be a potent inhibitor of one type of thrombotic episode, but inactive on another. We propose that the different effects of fucosylated chondroitin sulfate and its carboxyl-reduced derivative on venous thrombosis may be related to adherence of the glycosaminoglycan to the vessel wall.
Assuntos
Sulfatos de Condroitina/administração & dosagem , Sulfatos de Condroitina/química , Pepinos-do-Mar/química , Trombose Venosa/tratamento farmacológico , Acetilgalactosamina/química , Animais , Anticoagulantes/administração & dosagem , Anticoagulantes/química , Coagulação Sanguínea/efeitos dos fármacos , Artérias Carótidas/metabolismo , Artérias Carótidas/patologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Fucose/química , Ácido Glucurônico/química , Hemorragia/tratamento farmacológico , Heparina , Cofator II da Heparina/metabolismo , Masculino , Ratos , Ratos Wistar , Trombose Venosa/metabolismo , Trombose Venosa/patologiaRESUMO
Dermatan sulfate (DS) is a member of the family of structurally complex, sulfated, linear heteropolysaccharides called glycosaminoglycans (GAGs). It has a similar structure to heparin and heparan sulfate (HS), but with acetylgalactosamine replacing glucosamine, and the uronic acid moiety, mainly iduronic, joined 1-->3 to the hexosamine. We are studying the relationships between structure and activities of dermatan sulfate, in particular those associated with the thrombin inhibition mediated by heparin cofactor II (HCII). As we have demonstrated with heparin, a small fraction of dermatan sulfate was isolated by precipitation with the first component of the complement system, under very specific conditions of low ionic strength, and the presence of calcium ions. The sulfate content and the anticoagulant activity of the dermatan sulfate fraction isolated in the precipitate were three and four times greater respectively than the starting material. Our in vivo studies showed that this fraction has threefold higher thrombolytic activity than the DS. All these results suggest that this fraction could be used as a therapeutic agent for thrombi dissolution.
Assuntos
Anticoagulantes/química , Anticoagulantes/farmacologia , Complemento C1/metabolismo , Dermatan Sulfato/química , Dermatan Sulfato/farmacologia , Acetilgalactosamina/química , Animais , Anticoagulantes/isolamento & purificação , Anticoagulantes/metabolismo , Cálcio/química , Precipitação Química , Complemento C1/química , Complemento C1/isolamento & purificação , Dermatan Sulfato/isolamento & purificação , Dermatan Sulfato/metabolismo , Fibrinolíticos/farmacologia , Hexosaminas/química , Ácido Idurônico/química , Masculino , Concentração Osmolar , Ratos , Ratos Wistar , Relação Estrutura-Atividade , Sulfatos/químicaRESUMO
Most Trypanosoma cruzi O-glycans are linked to Thr/Ser residues via N-acetylglucosamine. We report that the mucin-type carcinoma-associated sialyl-Tn antigen (NeuAc-GalNAc-O-Ser/Thr) is expressed by T. cruzi. A specific MAb allowed us to localize the antigen on the surface of epimastigotes and to identify reactive components in parasite lysates (32, 60, and 94kDa). In addition, ppGalNAc-T activity was characterized in epimastigotes, and direct evidence was obtained for the in vitro incorporation of GalNAc to a synthetic peptide derived from a T. cruzi mucin. These results add an as yet unknown complexity to the pathways of O-glycan biosynthesis in this protozoan parasite.
Assuntos
Acetilgalactosamina/metabolismo , Antígenos Glicosídicos Associados a Tumores/metabolismo , Mucinas/metabolismo , N-Acetilgalactosaminiltransferases/metabolismo , Trypanosoma cruzi/metabolismo , Acetilgalactosamina/química , Sequência de Aminoácidos , Animais , Antígenos Glicosídicos Associados a Tumores/química , Ativação Enzimática , Técnica Direta de Fluorescência para Anticorpo/métodos , Concentração de Íons de Hidrogênio , Metaloendopeptidases , Dados de Sequência Molecular , Mucinas/química , N-Acetilgalactosaminiltransferases/química , Trypanosoma cruzi/químicaRESUMO
A dermatan sulfate-like glycosaminoglycan was isolated from the body of the ascidian Ascidia nigra (J. Biol. Chem. 270: 31027-31036, 1995). 1H NMR and fast atom bombardment mass spectrometry (FAB-MS) spectra of the tetra and disaccharides formed by chondroitin ABC lyase digestion support the proposed repeating disaccharide structure for this glycosaminoglycan, [-->4)-alpha-L-IdoA(2SO4)-(1-->3)-beta-D-GalNAc(6SO4)-(1-->] , which differ from mammalian dermatan sulfate in its sulfation at both 2-position of the alpha-L-iduronic acid and the 6-position of the N-acetyl-beta-D-galactosamine residue.
Assuntos
Condroitina Liases/metabolismo , Dermatan Sulfato/metabolismo , Urocordados/química , Acetilgalactosamina/química , Acetilgalactosamina/metabolismo , Animais , Dermatan Sulfato/química , Dermatan Sulfato/isolamento & purificação , Dissacarídeos/química , Dissacarídeos/metabolismo , Ácido Idurônico/química , Ácido Idurônico/metabolismo , Espectroscopia de Ressonância Magnética , Oligossacarídeos/química , Oligossacarídeos/metabolismo , Espectrometria de Massas de Bombardeamento Rápido de Átomos , Sulfatos/metabolismoRESUMO
The interaction of the vanadyl (IV) cation with N-acetyl-D-galactosamine, D-galactosamine, and D-glucuronic acid has been investigated by electron absorption spectroscopy at different metal to ligand ratios and pH values. In the case of D-glucuronic acid, a more detailed study was undertaken, using differential IR spectroscopy in solution. The results show that the cation interacts with the two nitrogenated molecules only at higher pH values, generating 2:1 ligand to metal complexes in which coordination occurs through two pairs of deprotonated OH groups of the rings. In the case of D-glucuronic acid, the IR-measurements allowed a wider insight into the structural characteristics of the complexes generated in acidic media. The involvement of the glycosidic oxygen atom in coordination, is suggested at pH = 3.
Assuntos
Acetilgalactosamina/química , Sulfatos de Condroitina/metabolismo , Galactosamina/química , Glucuronatos/química , Vanadatos/metabolismo , Acetilgalactosamina/metabolismo , Cátions Bivalentes , Sulfatos de Condroitina/química , Galactosamina/metabolismo , Glucuronatos/metabolismo , Ácido Glucurônico , Concentração de Íons de Hidrogênio , Ligantes , Espectrofotometria Atômica , Espectrofotometria Infravermelho , Vanadatos/químicaRESUMO
A dermatan sulfate, similar to the mammalian glycosaminoglycans but not identical with any of them, has been isolated from the body of the ascidian Ascidia nigra. Degradation with chondroitin ABC lyase, analysis of the disaccharide products by digestion with chondro-4- and -6-sulfatases, and 1H and 13C NMR data confirm that the predominant structure is [4-alpha-L-IdoA-(2SO4)-1-->3-beta-D-GalNAc(6SO4)-1]n. Mammalian dermatan sulfate is an anticoagulant due to its ability to potentiate inhibition of thrombin by heparin cofactor II. The structure in dermatan sulfate which binds to heparin cofactor II is [4-alpha-L-IdoA-(2SO4)-1-->3-beta-D-GalNAc(4SO4)-1]n, where n > or = 3. We have compared the ascidian dermatan sulfate with mammalian dermatan sulfate and with chemically oversulfated mammalian dermatan sulfate for anticoagulant activity as measured by the activated partial thromboplastin time assay and for its ability to potentiate heparin cofactor II. In spite of its high content of 2-O-sulfated alpha-L-iduronic acid residues, the ascidian compound had no discernible anticoagulant activity and had low ability to potentiate heparin cofactor II. These results suggest that 4-O-sulfation of the N-acetyl-beta-D-galactosamine residues is essential for the anticoagulant activity of dermatan sulfate.