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

---

Query: EC:3.2.1.36 (hyaluronidase)
4,606 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The chemical nature of anionic sites located on both fronts of the endothelial cells (ECs) and in the basement membrane (BM) of mouse brain capillaries was studied using tissue sections embedded in Lowicryl K4M and cationic colloidal gold. Before labelling with cationic probe, the sections were digested with the following enzymes: trypsin, papain, pronase E, proteinase K, collagenase, chondroitinase ABC, hyaluronidase, heparinase, heparitinase, neuraminidase and endoglycosidase H. The results indicate that the negatively charged surface layer on the luminal front differs in chemical nature from that on the abluminal front of the EC. Anionic sites located on the luminal surface of the plasmalemma of the ECs are mainly contributed by sialic acid residues of acidic glycoproteins. On the contrary, the anionic domains on the abluminal front of the EC represent mixed proteoglycan and acid glycopeptides containing hydrophobic amino acids, sialic acid residues, and are rich in heparan sulphate-bearing glycosaminoglycans. The anionic sites of the BM are contributed in a substantial degree by chondroitin and heparan sulphate-rich glycosaminoglycans. The effect of endoglycosidase H suggests that glycopeptides containing oligomannosyl residues linked to N-acetylglucosamine contribute in small degree in maintenance of the negative charge in the BM, but not on the surfaces of the EC. These results show that brain endothelium bears surface anionic domains differing chemically from those described for some fenestrated and continuous endothelia. The distribution of anionic sites indicates that the discrimination against various negatively charged molecules takes place on both fronts of the ECs as well as in the BM of brain micro-blood vessels. The exact role of these domains in the function of the blood-brain barrier remains to be established.
...
PMID:Ultracytochemical characterization of anionic sites in the wall of brain capillaries. 274 7

Sodium hyaluronate (HA) protects the corneal endothelium during cataract surgery. Recently, HA receptors have been found on liver endothelial cells that play an important role in HA catabolism. It is unknown if similar receptors are present on the corneal endothelium. In this study we have used two different methods to follow the interaction of HA with corneal endothelial cells: (1) binding of 3H-HA to cells or intact corneas was determined in the presence or absence of unlabelled glycosaminoglycans after solubilization with KOH, and (2) the HA-binding region of bovine cartilage proteoglycan was used as a histochemical probe and visualized by an avidin-biotin method. 3H-HA bound both to intact rat corneas pretreated with Streptomyces hyaluronidase and to cultured monkey corneal endothelial cells. The fraction-bound 3H-HA increased with time and was saturable. Cultured endothelial cells were estimated to have 1700-2100 binding sites per cell with a binding constant of 5.6-8.5 X 10(9) liters/mol. Furthermore, unlabelled HA displaced the tritiated in a dose-dependent manner and the displacing efficiency was dependent on molecular weight. The histochemical method disclosed that HA forms a continuous layer on the endothelium. If Healon was injected into the anterior chamber, the thickness and staining intensity of this layer increased conspicuously.
...
PMID:Hyaluronate binding to intact corneas and cultured endothelial cells. 279 54

Rabbit corneal proteoglycans were labeled by intrastromal injection of 3H-glucosamine and 35S-sulfate 1 and 2 weeks after partial-thickness radial scalpel incisions. Proteoglycans were extracted with guanidine-HCl and purified by ion exchange chromatography. Wounding caused a marked decrease in the total incorporation of labeled precursors into proteoglycans. The labeled proteoglycans were more readily extracted with guanidine-HCl after wounding. Labeled proteoglycans from wounded corneas had a larger molecular size on gel filtration chromatography than did proteoglycans from control corneas, a result of an increased amount of keratan sulfate in the large molecular size fractions. Analysis of labeled glycosaminoglycan (GAG) from guanidine-extracted proteoglycans and from the corneal tissue after guanidine-HCl extraction showed an increase in the relative amount of heparan sulfate and keratan sulfate after wounding, and a decrease in relative amount of dermatan sulfate. The 35S:3H ratio of heparan and dermatan sulfates increased after wounding, and that of keratan sulfate decreased, suggesting changes in sulfation. Degradation of labeled dermatan sulfate with hyaluronidase and with periodate revealed a 2-fold increase in iduronic acid content and 2-4-fold increase in hyaluronidase-resistant dermatan sulfate in the wounded corneas. Reduction in proteoglycan content, reduced sulfation of keratan sulfate, and accumulation of a high-sulfate, high-iduronic acid dermatan sulfate are previously reported properties of proteoglycan in scar tissue from perforating corneal wounds. Demonstration of these properties in proteoglycan after wounds similar to radial keratotomy incisions suggests that deposition of scar tissue can result from wounds which do not damage Descemet's membrane.
...
PMID:Proteoglycans of rabbit corneas with nonperforating wounds. 292 15

Monoclonal antibody-producing cell lines were derived from BALB/c mice immunized with a testicular hyaluronidase digest of tryptic fragments of bovine nasal cartilage proteoglycan. Sera and hybridoma culture supernatants were screened by solid-phase immunoassay for reactivity against a chondroitinase ABC digest of the same proteoglycan fragment fraction. Antibody specificity was determined by competitive inhibition with purified proteoglycan fragment subfractions and their enzymatically modified derivatives. Two monoclonal antibodies were produced which reacted with keratan sulfate-rich fragments from bovine nasal and human articular cartilage proteoglycan. One, monoclonal LC8.13, is directed against keratan sulfate itself, but differs from 5-D-4, a previously described monoclonal antibody to keratan sulfate, in its lesser reactivity with keratanase-treated fragments. The second, monoclonal F1.2, appears to be directed against a conformation-dependent determinant on the core protein of this segment of the cartilage proteoglycan monomer. Monoclonal F1.2 does not react with the keratan sulfate species in human and fetal calf serum and can therefore detect the production of keratan sulfate-bearing proteoglycan by chondrocytes cultured in serum-containing media.
...
PMID:Monoclonal antibodies reactive with keratan sulfate-bearing tryptic fragments of bovine nasal cartilage proteoglycan. 295 51

Corneas from mouse, rat and rabbit were analysed quantitatively and/or qualitatively for collagen and acid glycosaminoglycans. They were examined by light and electron microscopy, using Alcian blue and Cupromeronic blue, in critical electrolyte concentration methods, with or without digestion by hyaluronidase, chondroitinases and keratanase, for their sulphated glycosaminoglycan distributions. Glycosaminoglycan patterns were very different in the three species. Mouse lacked chemically detectable keratan sulphate, which was present in considerable amounts in rat and rabbit stroma. Mouse corneal stroma proteoglycan filaments were located predominantly at the gap zone of the collagen fibrils, mainly at the d band, with few at the a and c bands. Rat and rabbit micrographs were more complicated, with many proteoglycan filaments at the a and c, as well as the d and e bands. These findings support the proposal that the a and c bands were specific binding sites for keratan sulphate proteoglycan (Scott & Haigh, 1985b). Evidence from studies on cornea and cartilage suggests that keratan sulphate, rather than chondroitin sulphate is produced in conditions of O2 lack. Metabolic mechanisms which could account for this balance are proposed The production of uridine diphosphate glucuronic acid is the key step, which is sensitive to hypoxia, lactate and NAD:NADH ratios.
...
PMID:Keratan sulphate and the ultrastructure of cornea and cartilage: a 'stand-in' for chondroitin sulphate in conditions of oxygen lack? 297 65

Hyaluronan was substituted with tyramine-cellobiose on amino residues exposed after hydrazinolytic N-deacetylation of the polysaccharide. Nonsubstituted amino groups were reacetylated, and the carboxylic hydrazides were removed by treatment with HIO3. The adduct was labeled with 125I before or after coupling to hyaluronan. N-deacetylation increased with prolonged pretreatment with hydrazine, which also reduced the chain length of hyaluronan. Hydrazinolysis for 30 min produced hyaluronan with Mr 2.2-2.9 x 10(5). This material was substituted with varying amounts of tyramine-cellobiose (from 1 per 20 to 1 per 130 disaccharides). Hyaluronan labeled in this way was recognized by Streptomyces hyaluronidase, hyaluronan affinity protein of cartilage proteoglycan, and receptors for specific endocytosis of hyaluronan in liver endothelial cells. Since tyramine-cellobiose is nondegradable and therefore is arrested intralysosomally at the site of uptake, turnover studies of hyaluronan can be easily carried out with this ligand.
...
PMID:Preparation of biologically intact radioiodinated hyaluronan of high specific radioactivity: coupling of 125I-tyramine-cellobiose to amino groups after partial N-deacetylation. 307 Nov 84

Rabbit annulus fibrosus and nucleus pulposus were analysed for hydroxyproline, chondroitin sulphate, keratan sulphate and dermatan sulphate. Tissue proteoglycans were stained for electron microscopy with Cupromeronic blue, used in the critical electrolyte concentration mode, with and without prior digestion by chondroitinase AC or ABC, hyaluronidase or keratanase. Collagen bands, a-e were demonstrated with UO2++. A chondroitin sulphate proteoglycan was found orthogonally associated with loosely packed collagen fibrils in annulus fibrosus at the d and e bands. The close metabolic and structural analogies with the dermatan sulphate proteoglycans previously shown to be located at collagen d-e bands in tendon, skin, etc. (Scott and Haigh (1985) Biosci. Rep. 5:71-81), are discussed. Tightly packed annulus collagen fibrils were surrounded by axially oriented proteoglycan filaments, mostly without specific locations.
...
PMID:Proteoglycan-collagen interactions in intervertebral disc. A chondroitin sulphate proteoglycan associates with collagen fibrils in rabbit annulus fibrosus at the d-e bands. 310 6

A histochemical investigation was carried out on proteoglycans of bovine intervertebral disc. Samples obtained from the "annulus fibrosus" (A.F.) and "nucleus pulposus" (N.P.) were treated with Alcian blue (AB) diluted in solutions of MgCl2 at critical electrolyte concentrations (CEC); some samples were incubated in testicular hyaluronidase before AB treatment. At least four types of elongated AB-proteoglycan particles were recognized: a) in A.F. lamellae and N.P., 1 nm rod-like particles were arranged orthogonally to the collagen fibrils and spaced at a distance equivalent to the fibril D-period (Figs. 1-5); b) within the A.F. lamellae, other 16-20 nm particles formed a close network among the collagen fibrils (Figs. 1,2,3,5); c) in the A.F. interlamellar crevices, 30-50 nm leaf-like particles were present (Fig. 6); d) in the N.P.Z., 20-30 nm leaf-like particles formed a wide-mesh (Fig. 4). The alcianophylic particle sizes suggest they may correspond to proteoglycan monomers in the A.F. lamellae and mostly proteoglycan aggregates in A.F. interlamellar crevices and N.P.. Both alcianophylia degrees at MgCl2 CEC solutions and enzymatic susceptibility indicate the presence of chondroitin sulphate and keratan sulphate and that the large particles in the A.F. interlamellar crevices are the keratan sulphate richest proteoglycans. The features of the observed AB-proteoglycan particles are consistent with previous morphological data reported for other tissues as well as some biochemical data for the intervertebral disc and may be correlated to the composite mechanical properties of this tissue.
...
PMID:Localization of different alcian blue-proteoglycan particles in the intervertebral disc. 322 64

This paper examines the role of the extracellular matrix (ECM) in the development of the cornea. After a brief summary of the corneal structure and ECM, we describe evidence suggesting that the differentiation of neural crest (NC) cells into endothelium and fibroblasts is under the control of ocular ECM. We then examine the role of collagen I in stromal morphogenesis by comparing normal corneas with those of homozygous Mov 13 mice which do not make collagen I. We report that, in spite of this absence, the cellular morphology of the Mov13 eye is indistinguishable from that of the wild type. In the 16-day mutant stroma, however, the remaining collagens form small amounts of disorganized, thin fibrils rather than orthogonally organized 20 nm-diameter fibrils; a result implying that collagen I plays only a structural role and that its absence is not compensated for. It also suggests that, because these remaining collagens will not form the normal fibrils that they will in vitro, fibrillogenesis in the corneal stroma differs from that elsewhere. The latter part of the paper describes our current work on chick stromal deposition using corneal epithelia isolated with an intact basal lamina that lay down in vitro approximately 3 microns-thick stromas of organized fibrils similar to that seen in vivo. This experimental system has yielded two unexpected results. First, the amount of collagen and proteoglycans produced by such epithelia is not dependent on whether its substratum is collagenous and we therefore conclude that stromal production by the intact epithelium is more autonomous than hitherto thought. Second, chondroitin sulphate (CS), the predominant proteoglycan, appears to play no role in stromal morphogenesis: epithelia cultured in testicular hyaluronidase, which degrades CS, lay down stromas whose organization and fibril-diameter distribution are indistinguishable from controls. One possible role for CS, however, is as a lubricant which facilitates corneal growth: it could allow fibrils to move over one another without deforming their orthogonal organization. Finally, we have examined the processes of fibrillogenesis in the corneal stroma and conclude that they are different from those elsewhere in the embryo and in vitro, perhaps because there is in the primary stroma an unidentified, highly hydrated ECM macromolecule that embeds the fibrils and that may mediate their morphogenesis.
...
PMID:The extracellular matrix of the developing cornea: diversity, deposition and function. 325 Aug 51

The synthesis of extracellular [35S]-SO4- and [3H]-glucosamine-labelled glycosaminoglycan (GAG) was studied in confluent human gingival fibroblast cultures in vitro. The differential synthesis of the total chondroitin sulphate/dermatan sulphate (CS/DS) and heparan-sulphate (HS) fraction was measured following chondroitinase-ABC digestion, nitrous-acid treatment and column chromatography on Sephadex G50. Control cultures synthesized a CS/DS fraction that represented 78 per cent of the total [35S]-SO4-GAG; the residual 22 per cent was heparan sulphate. Similar cultures were labelled with [3H]-glucosamine and the proportions of a high molecular-weight hyaluronic acid (HA) and proteoglycan fractions measured by gel-filtration HPLC after papain and hyaluronidase digestions. The HA fraction represented 66 per cent of the total isotope incorporated in control cultures. GAG chains released on treatment with papain (24 per cent of the total label incorporated) were of apparent molecular weight 17-20 kDa. All cultures exposed to Bacteroides gingivalis W50 outer membrane at concentrations between 2 and 50 micrograms ml-1 displayed a decrease in the CS/DS fraction and a reciprocal increase in the HS. However, the proportion of HA synthesized was slightly enhanced with a reciprocal decrease in the proteoglycan (papain-digestible) fraction. There was no alteration in the molecular weight of the papain-digestion products or the size distribution of the hyaluronic-acid fraction.
...
PMID:The effect of the outer membrane fraction of Bacteroides gingivalis W50 on glycosaminoglycan metabolism by human gingival fibroblasts in culture. 325 24


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---