Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.2.2.7 (heparinase)
1,270 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A very high molecular weight mucin-like glycoprotein was isolated by gel filtration of interphotoreceptor matrix (IPM) from fresh bovine eyes and purified to apparent homogeneity by cesium chloride/guanidine hydrochloride (GuHCl) equilibrium density gradient centrifugation. Although a molecular weight in excess of 10(7) Da is suggested by gel filtration, the presence of SDS or GuHCl did not alter its elution position, indicating that the large size was not simply due to aggregation. Treatment of this material with disulfide reagents, however, led to a decrease in molecular size. On a relative basis, substantially more of this glycoprotein is present in IPM prepared from retina than from retinal pigment epithelium. While the carbohydrate and amino acid composition are not those of a true 'mucin', the large size and many other properties are quite 'mucin-like'. The carbohydrate composition suggests the presence of both N- and O-glycosidically linked sugar chains. The presence of a mucin-type O-glycosidic linkage is indicated by its susceptibility to alkaline cleavage, with concomitant loss of serine and threonine and increase in 240 nm absorbance; production of a fluorescent product upon reaction with cyanoacetamide; lectin binding properties; and production of N-acetylgalactosaminitol upon alkaline borohydride elimination. This glycoprotein was digested by pronase and trypsin, confirming its protein nature, but was resistant to digestion with chondroitin ABC lyase, hyaluronidase and heparinase, as well as RNAase, indicating that these components were not present to any appreciable extent. ELISA for cartilage keratan sulfate was also negative. Centrifugation in CsCl/GuHCl gradients indicated a density much lower than that of a proteoglycan or nucleic acid as well. In vitro biosynthetic studies suggest that both retina and retinal pigment epithelium may be major sources of material in the IPM. The elution patterns of radioactivity were strikingly similar to the UV elution patterns of IPM. The medium from retinal incubations contained very high molecular weight material which was resistant to enzymes which hydrolyse glycosaminoglycans, suggesting that retina may be the source of this high molecular weight, mucin-like glycoprotein.
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PMID:High molecular weight mucin-like glycoproteins of the bovine interphotoreceptor matrix. 154 29

Hemodynamic forces continuously act on endothelial cell lining of blood vessels. Blood flow, perfusing pressure, and shear stress are known to induce the release of bioactive substances from the endothelium. Furthermore, coronary flow (CF) is a well-known stimulant of myocardial contraction. Our concern was whether other Ca(2+)-dependent responses like glycolytic flux (Gf) were also CF dependent. For this purpose, isolated guinea pig hearts were perfused with a medium containing 5 mM 3-[3H]glucose, and the 3H2O released during perfusion was measured as an index of Gf. Changes in CF within the 3- to 25-ml/min range resulted in linear increase of Gf. This stimulatory effect of CF was also observed in K(+)-arrested hearts. In addition, increasing shear stress on addition of dextran to the perfusing solution (5% and 10% wt/vol), while keeping CF constant, also stimulated Gf. We hypothesized that endothelial cell membrane glycocalyx may act as sensor to this stimuli. Thus one would expect that substances acting on these structures (enzymes heparinase, hyaluronidase, or chondroitinase or the lectin concanavalin A) when added to the perfusate might inhibit the CF-induced Gf. The results showed that concanavalin A and heparinase inhibited the Gf-CF-induced response, whereas chondroitinase and hyaluronidase had no effect. These findings suggest that there may be a selective effect of these agents affecting the Gf response to CF. Our data suggest that CF stimulates Gf through shearing forces acting on specific endothelial glycocalyx component(s). Therefore, deformation of these components could result in the transduction of physical signals into release of chemical messengers that act on the biochemical machinery of underlining parenchymal cells.
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PMID:Regulation of glycolytic flux by coronary flow in guinea pig heart. Role of vascular endothelial cell glycocalyx. 175 May 47

We have isolated cDNA clones that code for a proteoglycan-related polypeptide with unique properties. A lambda gt11 expression library made from human fibroblast mRNA was screened with an antiserum made against a proteoglycan fraction from human fetal membranes. One group of positive clones revealed an open reading frame coding for 685 amino acids from the COOH terminus of a polypeptide. This amino acid sequence contains a domain that is strongly homologous with the COOH-terminal core protein domain of the large aggregating cartilage proteoglycan. This domain also contains sequences that are homologous with vertebrate lectins that bind terminal galactosyl, N-acetyl-glucosaminyl or mannosyl residues. On the NH2-terminal side of the lectin-like domain the cDNA-derived amino acid sequence contains two epidermal growth factor-related segments. The cDNA clones were shown to belong to a chondroitin sulfate proteoglycan by using antisera made against two peptides predicted from the cDNA sequence. These antisera were reactive with a proteoglycan fraction from fibroblasts after chondroitinase treatment of the fraction but not after treatment with heparinase or no treatment. Among the several polypeptides reactive with the anti-peptide antibodies the largest one, corresponding to a molecular weight of about 400,000, is likely to be the intact core protein, whereas the smaller polypeptides may be processing products or products of artifactual proteolysis. These results show that the amino acid sequence belongs to a proteoglycan core protein, and the sequence, therefore, provides a molecular definition to this proteoglycan. The lectin-related and growth factor-like sequences in the core protein of this proteoglycan suggest that it may play a role in intercellular signaling.
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PMID:A fibroblast chondroitin sulfate proteoglycan core protein contains lectin-like and growth factor-like sequences. 282 Sep 64

Glucosamine-labeled glycopeptides from control and virus-transformed BHK fibroblasts were characterized by size, lectin affinity, charge, and composition. As already demonstrated, on the basis of elution position on a column of Sephadex G-50, transformed cells contained a greater proportion of large glycopeptides than did control cells. Transformed cells also contained a larger proportion of glycopeptides which do not bind to Con A-Sepharose. By sequential chromatography on Sephadex G-50, Con A-Sepharose, and DEAE-Sephadex, approximately 40 individual peaks were partially or completely resolved. If sialic acid was removed from the glycopeptides prior to analysis by ion-exchange chromatography, 95% of the glycopeptides from control cells and 85% of the glycopeptides from transformed cells were no longer bound by DEAE-Sephadex. It was concluded that the DEAE-Sephadex elution properties of the glycopeptides are determined almost entirely by the sialic acid content of the molecules. A comparison of the profiles of control and transformed cell glycopeptides simultaneously eluting from columns of DEAE-Sephadex revealed that the differences between the two cells were largely quantitative; however, the possibility of the existence of qualitative differences as well cannot be excluded. In particular, there was one component present on the surface of transformed cells that was virtually absent in control cells. It was degraded by nitrous acid hydrolysis and heparinase and appeared to be heparan sulfate like material. After fractionation, each isolated glycopeptide population was analyzed for carbohydrate and, in some cases, amino acid content. The apparently larger glycopeptides, group A, the dominant population in transformed cells, were found to contain 3 to 4 mannose residues/glycopeptide when the sugars were normalized to sialic acid content. On the basis of the same criteria, group B glycopeptides contained 4-6 mannose residues/glycopeptide. The carbohydrate and amino acid compositions of the glycopeptides from transformed cells were, with a few exceptions, similar to those from control cells. Some isolated glycopeptides appeared to contain both O-glycosidic anad N-glycosidic linkages on the same oligopeptide.
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PMID:Comparison of glycopeptides from control and virus-transformed baby hamster kidney fibroblasts. 625 May 68

We report here that interleukins have a dramatic effect on extracellular matrix production by cultured endothelial cells. Human umbilical vein endothelial cells incubated with growth media conditioned by lectin-activated human peripheral blood mononuclear leukocytes undergo marked changes in cell shape and elaborate a highly organized extracellular material that is not detectable in untreated cultures. This material has the following characteristics: (a) it is not recognizable by electron microscopy unless the cationic dye, Alcian blue, is added to the fixative; (b) it is visualized as a network of branching and anastomosing fibrils of various thickness that can be resolved into bundles of fine filaments; (c) it is associated with the cell surface, extends between contiguous cells, and coats the culture substrate; (d) it is removed by digestion with glycosaminoglycan-degrading enzymes, such as crude heparinase and chondroitinase ABC. These results demonstrate that soluble factors released by activated peripheral blood mononuclear leukocytes (interleukins) stimulate cultured human umbilical vein endothelial cells to produce a highly structured pericellular matrix containing glycosaminoglycans (probably chondroitin sulfate and/or hyaluronic acid) as a major constituent. We speculate that this phenomenon corresponds to an early step of angiogenesis as observed in vivo as a consequence of interleukin release.
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PMID:Leukocyte interleukins induce cultured endothelial cells to produce a highly organized, glycosaminoglycan-rich pericellular matrix. 633 26

Using the sialic acid-specific lectin, limulin (LPA; from Limulus polyphemus hemolymph), the distribution and nature of sialoglycoconjugates on the surface of rat pancreatic cells has been investigated. Binding of rhodaminated LPA (Rh-LPA) or horseradish peroxidase-conjugated LPA (HRP-LPA) to fixed-frozen sections of adult rat pancreas resulted in intense linear staining of the apical surface of acinar cells with fainter staining on the basal but not the lateral cell surfaces. LPA binding was specific in that it could be abolished by 1) pretreatment of tissue sections with neuraminidase or periodic acid; 2) competition with sialic acid; and 3) incubation in Ca2+ -free buffers. Pretreatment of sections with proteases abolished LPA binding to the apical surfaces of acinar cells and also enhanced LPA binding to the lateral cell surface. Lipid extraction of sections following protease treatment markedly reduced LPA binding to the acinar cell periphery. These results suggest that LPA binding sites on the acinar cell apical surface may be primarily sialoglycoproteins, while those on the basolateral surfaces may consist in part of gangliosides. Electron microscopy of collagenase-dispersed acini exposed to HRP-LPA confirmed binding of LPA to the basal plasmalemma and, in addition, revealed staining of basal lamina when present. LPA binding to the acinar cell surface was not affected by digestion of tissue sections with hyaluronidase, heparinase, collagenase, or 6 M guanidine-HCl. Control experiments indicated that rat pancreatic secretory proteins contain undetectable amounts of sialoglycoproteins and thus that the apical localization of LPA is not due to adherent secretory proteins. Islets of Langerhans were always uniformly and heavily stained with LPA conjugates; this staining was protease insensitive. Appearance of LPA binding sites was examined on embryonic pancreatic epithelia. At day 15 of gestation, Rh-LPA stained the entire periphery of the epithelial cells, including the lateral cell surface, although more intense staining was already noted on the apical surface. This pattern persisted through day 17 of gestation, but by day 19 an adult staining pattern was observed with loss of staining of the lateral cell surfaces.
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PMID:Distribution of sialoglycoconjugates on acinar cells of the mammalian pancreas. 675 68

The ability of the Lyme disease spirochete to attach to host components may contribute to its ability to infect diverse tissues. We present evidence that the Lyme disease spirochete expresses a lectin activity that promotes agglutination of erythrocytes and bacterial attachment to glycosaminoglycans. Among a diverse collection of 21 strains of Lyme disease spirochete, hemagglutinating activity was easily detected in all but 3 strains, and these three strains were noninfectious. The ability to agglutinate erythrocytes was associated with the ability of the spirochete to bind to the sulfated polysaccharide dextran sulfate and to mammalian cells. Soluble dextran sulfate was a potent inhibitor of both hemagglutination and attachment to mammalian cells, while dextran had no effect on either activity, suggesting that dextran sulfate may inhibit attachment by mimicking host cell glycosaminoglycans. Consistent with this, the spirochete bound to immobilized heparin, and soluble heparin inhibited bacterial adhesion to mammalian cells. The bacterium did not bind efficiently to Vero cells treated with heparinase or heparitinase or to mutant CHO cell lines that are deficient in proteoglycan synthesis. Sulfation of glycosaminoglycans was critical for efficient bacterial recognition, as Vero cells treated with an inhibitor of sulfation, or a mutant CHO cell line that produces undersulfated heparan sulfate, did not mediate maximal spirochetal binding. Binding of the spirochete to extracellular matrix also appeared to be dependent upon this attachment pathway. These findings suggest that a glycosaminoglycan-binding activity which can be detected by hemagglutination contributes to the attachment of the Lyme disease spirochete to host cells and matrix.
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PMID:Hemagglutination and proteoglycan binding by the Lyme disease spirochete, Borrelia burgdorferi. 753 28

L-Selectin is a calcium-dependent mammalian lectin that mediates lymphocyte trafficking by recognizing sialylated ligands on high endothelial venules in lymph nodes. Although L-selectin probably mediates neutrophil extravasation into nonlymphoid tissues, no corresponding ligand has been characterized. Staining of cultured endothelial cells with an L-selectin chimera (LS-Rg) showed an internal pool of ligands. Metabolic labeling with sulfur-35-labeled sulfate revealed heparin lyase-sensitive ligands that bound LS-Rg in a calcium-dependent, sialic acid-independent manner. A fraction of commercial heparin bound to LS-Rg and LS-Rg bound to heparin-agarose, both in a calcium-dependent manner. Thus, L-selectin recognizes endothelial heparin-like chains, which could be physiological ligands mediating leucocyte trafficking.
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PMID:Calcium-dependent heparin-like ligands for L-selectin in nonlymphoid endothelial cells. 768 82

Previous studies have suggested that mucin gene expression is tissue-specific; however, the relationship between unique mucin gene products and the biochemical properties of mucins is unknown. The purpose of this study was to determine the biochemical and molecular characteristics of mucin synthesized by adenocarcinoma cell lines derived from breast (ZR-75-1), stomach (MGC-803), pancreas (Capan-2), and lung (Chago K-1). Mucin was quantitated by [3H]glucosamine labeling and Sepharose CL-4B chromatography. The mucinous nature of the labeled high molecular weight glycoproteins (HMG) was verified by alkaline borohydride treatment, cesium chloride density gradient ultracentrifugation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Specific mucin gene expression was determined using cDNA probes for 2 distinct intestinal mucins (MUC-2 and MUC-3) and one breast cancer mucin (MUC-1). Specific core mucin proteins were confirmed by immunoblots using antibodies that recognize MUC-1, MUC-2, and MUC-3 core peptides. These experiments demonstrate that all cell lines contained HMG in the medium, cytosol, and membrane fractions. The HMG was mucinous in breast, pancreatic, and lung cell lines. In contrast, most of the HMG secreted by the gastric cell line was proteoglycan-like, due to its susceptibility to hyaluronidase, heparinase, and chondroitinase avidin-biotin complex. Ion-exchange (DEAE-Sephacel) chromatography of [3H]glucosamine-labeled HMG demonstrated that the acidic or basic nature of the mucin was different in all cancer cell lines tested. Despite these differences, mRNA and immunoblot analysis suggest that all cell lines predominantly express MUC-1 apomucin, small amounts of MUC-2 apomucin, and no MUC-3. Immunoprecipitation of MUC-1-type mucin using the 139H2 monoclonal antibody demonstrated that different sizes of mucin peptides were present in all cell lines, corresponding to the known length polymorphism of this mucin. The amount and nature of carbohydrate epitopes were analyzed by immunoblots using anti-T (peanut lectin), anti-Tn (91S8 monoclonal antibody), and anti-sialosyl Tn (JT10e monoclonal antibody). T and Tn antigens were significantly higher in breast and pancreatic cells as compared with lung and gastric cell lines. These findings correlated with increased activities of polypeptidyl N-acetylgalactosaminyl transferase and beta-1,3-galactosyltransferase.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Mucin synthesis and secretion in various human epithelial cancer cell lines that express the MUC-1 mucin gene. 844 22

Types and distribution patterns of glycoconjugates in antral ovarian follicles were investigated in the buffalo, using periodic-acid Schiff (PAS), high iron diamine (HID), low ion diamine (LID) and lectin histochemical staining methods. HID and LID staining procedures were preceded in some cases by digestion with testicular hyaluronidase, Streptomyces hyaluronidase, chondroitinase ABC and heparitinase (heparinase III). Lectin staining was performed with the use of 12 horseradish peroxidase (HRP) lectin conjugates. Some lectin staining procedures were preceded by neuraminidase digestion and saponification. Large amounts of isomeric chondroitin sulphates and a minor quantity of heparan sulphate and hyaluronic acid and/or chondroitin were found in follicular fluid. Lectin staining of buffalo follicular fluid revealed glycoconjugates with different glucidic determinants such as beta-N-acetylgalactosamine, beta-galactose-(1-3)-N-acetylgalactosamine, beta-galactose-(1-4)-N-acetylglucosamine, N-acetylglucosamine, alpha-fucose and alpha-glucose/alpha-mannose, and sialic acid residues. Glycosaminoglycans were absent in the zona pellucida of oocytes in small antral follicles. Acidic glycoconjugates in the zona pellucida were caused by sulphated groups and sialic acid residues. Our data show few internal glucidic residues, such as N-acetylglucosamine in the buffalo zona pellucida but many subterminal beta-N-acetylgalactosamine, alpha- and beta-galactose determinants masked by sialic acids. These findings demonstrate that buffalo follicular fluid has a very heterogeneous composition that is similar to that found in small and large bovine follicles. No differences in composition of the follicular fluid were observed in the follicles examined.
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PMID:Glycoconjugates in small antral ovarian follicles of the river buffalo (Bubalus bubalis L.). 971 61


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