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:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The chondrocyte is a specialized cell that synthesizes proteoglycans of a type found only in cartilage and nucleus pulposus. These proteoglycans are distinct in forming multiple aggregates of unique structure in which hyaluronic acid provides a central chain to which many proteoglycan molecules are bound at one end only. Chondrocytes were isolated from adult cartilage and used in suspension culture to test the effect of compounds in the medium on the synthesis of proteoglycans. Hyaluronic acid alone, among a number of compounds extracted from or analogous to those in cartilage, reduced the incorporation of [35S] sulphate into macromolecular material. Oligosaccharides of hyaluronic acid of the size of decasaccharides and above also had this effect but hyaluronic acid already bound to proteoglycan did not. The proportion of total labelled material associated with the cells increased at the expense of that in the medium. Treatment of the cells with trypsin abolished the effect of hyaluronic acid but treatment with chondroitinase did not. It is suggested that hyaluronic acid interacts with proteoglycans at the cell surface by a specific mechanism similar to that involved in proteoglycan aggregation, as a result of which the secretion and synthesis of proteoglycans is reduced.
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PMID:Influence of the cells on the pericellular environment. The effect of hyaluronic acid on proteoglycan synthesis and secretion by chondrocytes of adult cartilage. 23 23

The concanavalin A (Con A)-induced agglutinability of normal, preneoplastic, and neoplastic mouse mammary epithelial cells was examined. Cells freshly dissociated from normal mammary glands, hyperplastic alveolar nodules, or primary mammary adenocarcinomas by collagenase digestion in the presence of bovine serum albumin were strongly agglutinated by low concentrations of Con A. After short-term culture in vitro, however, cells from all three types of tissue were only weakly agglutinated by Con A, as measured by both suspension and hemadsorption assays. By comparison, cells of three established mammary tumor culture lines agglutinated strongly in the presence of the lectin. Treatment of the normal, preneoplastic, and neoplastic mammary cells in primary cultures with either trypsin or collagenase had little or no effect on their agglutinability, whereas hyaluronidase significantly increased their reactivity. Studies with fluorescein-tagged Con A indicated that all three cell types were capable of binding the lectin. The results were consistent with previous evidence suggesting that neoplastic transformation of mouse mammary epithelial cells is not manifested in vitro by several of the alterations in growth patterns, intercellular interactions, and surface properties that usually accompany transformation of fibroblastic cells.
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PMID:Concanavalin A-induced agglutinability of normal, preneoplastic, and neoplastic mouse mammary cells. 28 51

The distribution of glycosaminoglycans and glycoproteins has been studied in cytoplasmic and particulate fractions of neurons isolated in bulk from rat cerebrum. Lysis of the neurons in 25 mM sodium phosphate buffer at pH 7.5 released 20% of the protein and over 90% of the lactate dehydrogenase in a soluble form. Eighty-two percent of the chondroitin sulfate was also released, together with 55% of the heparan sulfate and 24-25% of the hyaluronic acid and glycoproteins. The chondroitin sulfate remaining in the membranes was completely depolymerized to disaccharides after treatment with chondroitinase ABC, and treatment of the neuronal membranes with 0.1% trypsin removed 55-63% of the chondroitin sulfate and heparan sulfate but only 25% of the sulfated glycoproteins. The results reported here support our previous conclusion that the soluble chondroitin sulfate proteoglycan of brain is largely a cytoplasmic constitutent of neurons (and astrocytes) and is not primarily present in nervous tissue as an extracellular ground substance.
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PMID:Presence of chondroitin sulfate in the neuronal cytoplasm. 28 11

The adherence of group A streptococci to epithelial cells was studied by using streptococcal strains labeled with [(3)H]uridine or fluorescein isothiocyanate. The ability of the labeled organisms to adhere to Detroit 562 epithelial cells, derived from a human pharyngeal carcinoma, as well as to epithelial cells scraped from the oral cavity was determined. Adherence to monolayer cultures or cell suspensions of Detroit cells compared favorably with adherence to suspensions of human oral epithelial cells. Initial experiments to determine the optimal conditions for adherence showed that adherence was temperature dependent and that the optimal incubation time was 15 min for adherence to epithelial cells in suspension and 30 to 60 min for monolayer cultures. Both streptococci and epithelial cells exhibited specificity in the adherence process. Different streptococcal strains varied in their ability to adhere. Adherence was also affected by the growth stage of the bacterial cultures. Trypsin treatment of the streptococci slightly decreased adherence, whereas hyaluronidase treatment increased the adherence of some strains. Streptococci were found to adhere to only about half of the epithelial cells. Those epithelial cells apparently have a limited number of receptor sites since they can be saturated by adding increasing concentrations of bacteria. Further support for limited receptor sites was provided by competition experiments. Adherence was inhibited by trypsin treatment of the epithelial cells, suggesting that proteins in the epithelial cell membrane may play a role in streptococcal adherence.
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PMID:Adherence of group A streptococci to human epithelial cells. 35 28

Transfer of radioactive materials to fixed cells from an overlying layer of living cells has been examined to determine whether fixed cells can act as acceptors of glycosyltransferases of living cells. After the incubation of living cells were removed by EDTA treatment, and the radioactivity associated with the fixed cells was determined. Lipids, proteins and carbohydrates were found to be transfered from the living cells to the fixed cells. The amount of radioactivity transferred to the fixed cells was dependent on the number of both fixed and living cells and increased with the time of incubation. When fixed cells were treated with chloroform-methanol before the addition of living cells, the transfer of both lipids and proteins to the fixed cells decreased drastically, but only a slight decrease incarbohydrate transfer was observed. Most of the radioactive materials transferred from living cells labeled with glucosamine or fucose to chloroform-methanol-treated fixed cells were solubilized by trypsin but not by the detergents tested. Approximately 55% of the materials transferred from the cells labeled with glucosamine could be solubilized by hyaluronidase and chondroitinase, and the rest was solubilized by neuraminidase and a glycosidase mixture. The treatment of chloroform-methanol-extracted fixed cells with trypsin caused a significant decrease in the transfer from cells labeled with glucosamine. When nucleotide sugars were used as the radioactive precursor, no significant amount of radioactivity was transferred to the fixed cells.
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PMID:Cellular interaction between fixed and living cells. Transfer of radioactive materials from living cells to fixed cells. 37 19

Russian investigators have recently reported clinical recovery of enzyme treated, spinal cord transected rats. Using the exact protocols of Matinian and Andreasian's two most successful treatment regimens, we repeated their experiments using United States produced pure hyaluronidase and trypsin or trypsin and elastase. Animals were evaluated for return of bladder function, clinical evidence of hind limb motor function, cortical evoked response after sciatic nerve stimulation, and axonal transport of cortically injected tritiated proline by regenerated corticospinal axons. None of the treated animals differed from control animals treated only with the enzyme vehicle. No animals walked, had return of voluntary motor activity, showed cortical evoked response, or had evidence for transport of tritiated proline over regenerated corticospinal axons.
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PMID:Enzyme treatment of spinal cord transected rats. 42 86

Cell responses to different natural substrates have been followed by scanning microscopy in order to evaluate the role of these substrates in morphogenesis. Matrix has been isolated then repopulated with suspensions of embryonic cells from chick skin, spinal ganglia, duodenal epithelium and heart. In some cases outgrowth from amphibian embryonic tissue was used. Basal lamina of the Xenopus tail may be exposed by freezing and thawing the tissue, or by EDTA treatment. The underlying lamella of orthogonally oriented collagen fibers may be exposed by use of trypsin or hyaluronidase. Trypsin causes more clumping of collagen fibers and a coarser texture of the matrix. On trypsin isolated basement lamella, nerve cell processes grow out on the surface and show no strong tendency to penetrate the lamella while skin mesenchymal cells commonly burrow among the collagen plies. Epithelial cells remain on the surface. On the basal lamina mesenchymal cells ruffle in early stages of culture, then flatten. Epithelial cells flatten rapidly on the lamina. These differences in cell response are in some cases closely related to cell behavior in vivo and suggest that cells show a selective response to the chemical composition of the substrate as well as to its physical conformation.
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PMID:Differential response of embryonic cells to culture on tissue matrices. 45 99

Soluble 125I-labeled type I collagen binds to cultured fibroblasts but not to cultured epithelia. The binding of the ligand to fibroblasts is reversible, saturable and highly specific for sequences contained within the helical portions of the alpha1 and alpha2 chains. The amount of ligand bound is dependent upon cell number and ligand concentration. Binding is decreased but measurable at 4 degrees C. The steady state binding is greater at 26 degrees than at 37 degrees C due to a more rapid dissociation of the ligand-acceptor complex at 37 degrees C. The half-life of the complex is 46 min at 37 degrees C and approximately 2.5 hr at 26 degrees C. Scatchard plots of binding data indicate a single class of high affinity binding sites (KD = 1.2 X 10(-11) M) with each fibroblast binding approximately 500,000 molecules at saturation. Pretreatment of fibroblasts with bacterial collagenase, chondroitinase ABC or testicular hyaluronidase does not affect the binding reaction, whereas pretreatment of the cells with phospholipase C increases the amount of ligand bound. Ligand binding is decreased but not abolished after fibroblasts are treated with trypsin concentrations which remove surface fibronectin. Fibroblast monolayers treated with antiserum against fibronectin bind the radiolabeled ligand normally. In contrast to collagen, addition of excess fibronectin does not accelerate the dissociation of bound ligand from fibroblasts. Possible functions for surface-bound collagen are discussed.
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PMID:Binding of soluble type I collagen molecules to the fibroblast plasma membrane. 45 36

Erythrocytes of different species (chicken, sheep, man, mouse, rat, guinea pig) except rabbit erythrocytes strongly adhere to the marginal zone of mouse spleen follicles in frozen sections. This adherence reaction (AR) is not restricted to red blood cells but is also observed with human lymphocytes. Pretreatment of the tissue sections with trypsin, mercaptoethanol, periodate, chloroform/methanol, acetone, and heating the sections abolishes AR whereas neuraminidase (VCN) treatment of the sections has an amplifying effect. AR is inhibited by preincubation of the neuraminidase- or untreated sections with neuraminic acid (NA). Treatment of the erythrocytes with VCN completely abolishes AR whereas treatment with other enzymes (hyaluronidase, collagenase) is ineffective in this respect. Determination of NA in the erythrocyte membrane before and after VCN treatment reveals a positive correlation between the amount of NA and AR. Rabbit red blood cells have the lowest NA content in their membranes and, in addition, there is little effect of VCN treatment in further reducing it. It is possible that a lectin-like substance is responsible for AR. The biologic significance of AR is hypothetical, but since AR occurs in an area of the spleen playing a role in antigen trapping it is conceivable that this trapping may be mediated by interaction of NA and NA receptor(s).
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PMID:Erythrocyte adherence to the marginal zone of mouse spleen follicle mediated by receptor(s) for neuraminic acid. 46 83

The binding of hyaluronate to SV-3T3 cells was measured by incubating a suspension of cells (released from the substratum with EDTA) with 3H-labeled hyaluronate and then applying the suspension to glass fiber filters which retained the cells and the bound hyaluronate. The extent of binding was a function of both the concentration of labeled hyaluronate and the cell number. Most of the binding took place within the first 2 min of the incubation and was not influenced by the presence or absence of divalent cations. The binding of labeled hyaluronate to SV-3T3 cells could be prevented by the addition of an excess of unlabeled hyaluronate. High molecular weight preparations of hyaluronate were more effective in preventing binding than low molecular weight preparations. The binding of [3H]hyaluronate was inhibited by high concentrations of oligosaccharide fragments of hyaluronate consisting of six sugars or more, and by chondroitin. The sulfated glycosaminoglycans (chondroitin-4-sulfate, chondroitin-6-sulfate, dermatan sulfate, heparin, and heparan sulfate) had little or no effect on the binding. The labeled hyaluronate bound to the cells could be totally removed by incubating the cells with testicular hyaluronidase, streptomyces hyaluronidase, or trypsin, indicating that the hyaluronate-binding sites are located on the cell surface.
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PMID:Binding of hyaluronate to the surface of cultured cells. 47 11


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