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

The binding of phosphatidylcholine and cholesterol in model bile to human gallbladder mucin was studied by means of a rapid filtration binding assay and sucrose density gradient ultracentrifugation. Numerous low affinity binding sites for phosphatidylcholine and cholesterol were present on gallbladder mucin. Binding of phosphatidylcholine and cholesterol to mucin increased as a function of cholesterol saturation index. Proteolytic digestion of mucin disaggregated the native mucin polymer and removed hydrophobic domains on the mucin peptide core that bind l-anilino-8-naphthalenesulfonic acid. Proteolytic digestion also resulted in a 91% and 78% decrease, respectively, in the binding of phosphatidylcholine and cholesterol to mucin. The ability of trypsin-treated and native mucin to promote the nucleation of cholesterol monohydrate crystals was compared in a model bile. The incidence of cholesterol monohydrate crystal nucleation with native mucin was significantly greater at 3 days than with trypsin-treated mucin or controls (P less than 0.001). After 3, 6, and 9 days of incubation, samples containing native mucin contained significantly more crystals than controls or trypsin-digested mucin samples (P less than 0.0001 for each). These data indicate that highly purified human gallbladder mucin binds phosphatidylcholine and cholesterol in model bile. Furthermore, this study demonstrates that structural integrity of the native mucin polymer and hydrophobic domains on the peptide core are essential for the nucleation of cholesterol monohydrate crystals by mucin in model bile.
...
PMID:Human gallbladder mucin binds biliary lipids and promotes cholesterol crystal nucleation in model bile. 365 61

Mucin glycopeptides were isolated from rat small intestinal mucosa after reduction/alkylation, trypsin digestion and gel chromatography. The oligosaccharides were released by using alkaline-NaBH4, separated into neutral and acidic species and permethylated. The derivatized mixtures were analysed with fast atom bombardment mass spectrometry and gas chromatography-mass spectrometry using thin film columns. Permethylated neutral oligosaccharides with up to seven sugars could be chromatographed and detected with mass spectrometry. The complex mixture revealed was partly due to the linkage GalNAc being substituted at both position 3 and 6. The approach will be very useful when analysing small amounts of mucins and mucin fragments.
...
PMID:Rapid characterization of mucin oligosaccharides from rat small intestine with gas chromatography-mass spectrometry. 369 14

The molecules involved in homotypic aggregation of the human Burkitt-lymphoma cell line Raji were investigated by inhibition of reaggregation with carbohydrates and glycoconjugates, by inhibition of glycosylation, and enzyme treatment of the cell surface. Complete inhibition of reaggregation was achieved with bovine submaxillary mucin. Asialomucin, on the other hand, was not effective in this assay. Another potent inhibitor of reaggregation was the ganglioside GMI. The common carbohydrate structure of these molecules is NeuNAc-(gal)-galNAc. Lactosamine, fucosyllactosamine, sialyllactosamine, complex mannose type, or Thomsen-Friedenreich antigen sequences are not involved in aggregation. Neuraminidase and chloroquine also abolished agglutination of cells. The finding that mucin, but not asialomucin, inhibits the reaction, demonstrates the importance of sialic acid in this process. Homotypic aggregation was shown to be resistant to trypsin. Using the glycosylation inhibitor tunicamycin we show that N-glycosidically linked carbohydrate chains are involved in aggregation. Swainsonine or castanospermine, which inhibit processing of terminal sialyllactosamines to the mannose core, did not interfere with the reaction supporting the results of the inhibition assay. The data presented suggest the involvement of 2 molecules in homotypic aggregation of human Burkitt-lymphoma cells. One component is a lectin-like molecule containing N-linked carbohydrate chains. The other component carries the neuraminidase-sensitive and trypsin-resistant determinant NeuNAc-(gal)-galNAc and, therefore, appears to be a glycolipid. This proposed lectin-carbohydrate interaction in homotypic aggregation is further supported by the frequently observed dependence of lectins on divalent cations as indicated by inhibition of aggregation with EDTA and EGTA.
...
PMID:Inhibition of homotypic aggregation of a human Burkitt-lymphoma cell line. 369 25

This report presents a new approach to the study of the colonization of the digestive tract after birth. We have examined the development of four microflora associated characteristics, MACs, defined as the recording of any anatomical structure, biochemical or physiological function in the macroorganism, which has been influenced by the microflora. These MACs may create a basis for later investigations into the impact of diarrheal diseases and antibiotic therapy. The following biochemical characteristics were studied in feces from children of 0-61 months of age: conversion of cholesterol to coprostanol and bilirubin to urobilins, inactivation of trypsin and degradation of mucin. These results indicate establishment of microbes capable of converting bilirubin to urobilins within the second year of life. The mucin degrading and cholesterol converting microbes are established in most of the children during the same period. Tryptic activity was found to be absent in meconium, present in feces from all children up to 21 months of age, and absent in 6 out of 15 children in the age group 46-61 months. The study indicates that the establishment of the MACs in the digestive tract is a remarkably long drawn out process.
...
PMID:The establishment of some microflora associated biochemical characteristics in feces from children during the first years of life. 392 99

The cell surface glycopeptides from an epithelial cell line (CCL 239) derived from normal human colon were compared with those from three cell lines (HCT-8R, HCT-15, and CaCo-2) derived independently from human colonic adenocarcinomas. Cells were incubated with D-[2-3H]mannose or L-[5,6-3H]fucose for 24 h and treated with trypsin to release cell surface components which were then digested exhaustively with Pronase and fractionated on Bio-Gel P-6 before and after treatment with endo-beta-N-acetylglucosaminidase H. The most noticeable difference between the labeled glycopeptides from the tumor and CCL 239 cells was the presence in the former of an endo-beta-N-acetylglucosaminidase H-resistant high molecular weight glycopeptide fraction which was eluted in the void volume of Bio-Gel P-6. This fraction was obtained with both labeled mannose and fucose as precursors. However, acid hydrolysis of this fraction obtained after incubation with [2-3H]mannose revealed that as much as 60-90% of the radioactivity was recovered as fucose. Analysis of the total glycopeptides (cell surface and cell pellet) obtained after incubation with [2-3H]mannose showed that from 40-45% of the radioactivity in the tumor cells and less than 10% of the radioactivity in the CCL 239 cells was recovered as fucose. After incubation of the HCT-8R cells with D-[1,6-3H]glucosamine and L-[1-14C]fucose, strong acid hydrolysis of the labeled glycopeptide fraction excluded from Bio-Gel P-6 produced 3H-labeled N-acetylglucosamine and N-acetylgalactosamine. This high molecular weight glycopeptide fraction was susceptible to mild alkaline borohydride reduction, yielding a mixture of labeled oligosaccharides which contained N-acetylgalactosaminitol. Thus, the HCT-8R cells are expressing fucosylated mucin-type glycoproteins on their surface.
...
PMID:Cell surface glycopeptides from human intestinal epithelial cell lines derived from normal colon and colon adenocarcinomas. 405 24

Mucus glycoproteins (mucins) were isolated from cervical and gastric mucus as well as from chronic bronchitic sputum. The mucus gel was solubilized by slow stirring in 6M-guanidinium chloride supplemented with low-Mr proteinase inhibitors. Subsequent removal of non-mucin proteins and DNA was achieved with isopycnic density-gradient centrifugation. The cervical and the respiratory mucins were of similar size (Mr about 10 X 10(6) and 18 X 10(6)), respectively), whereas the gastric mucins were considerably larger (Mr about 45 X 10(6)). 'Subunits' isolated after disulphide bond cleavage were the same size for the three mucins, as were glycopeptides obtained after subsequent trypsin digestion of the subunits. Physical data suggest that the respiratory and gastric mucins conform to the model for the polymeric structure proposed previously for cervical mucins. The macromolecules are described as linear flexible chains behaving, in dilute solution, as random coils. We propose that mucus glycoproteins are considerably larger than hitherto recognized and that mucins of various origins are very similar in their macromolecular properties and polymeric structure.
...
PMID:Macromolecular properties and polymeric structure of mucus glycoproteins. 608 49

The polypeptide core of mucin glycoprotein subunits resists cleavage by proteases. To determine if the carbohydrate side chains of these subunits protect the underlying polypeptide core from proteolytic cleavage, we compared the effect of pancreatic proteases on hog gastric mucin before and after cleavage of its carbohydrate moieties by bacterial glycosidases from an anaerobic human fecal culture supernate. Hog gastric mucin was resistant to pancreatic proteases: less than 10% of the mucin protein became soluble in 80% vol/vol ethanol after 24-h incubation with trypsin, alpha-chymotrypsin, and elastase, and its elution pattern from Sephadex G-200 remained unchanged after elastase treatment, with 90% eluting at the void volume. By contrast, after removal of 50% of its carbohydrates, mucin was susceptible to pancreatic proteases: 50% of mucin protein became soluble in 80% vol/vol ethanol after 24-h incubation with alpha-chymotrypsin and elastase, and 24% of mucin protein became soluble in 80% vol/vol ethanol after 24-h incubation with trypsin; after elastase treatment, its elution from Sephadex G-200 was markedly retarded. We conclude that the carbohydrate side chains of hog gastric mucin glycoprotein protect the underlying polypeptide core from proteolysis and that degradation of the carbohydrate side chains by glycosidases from fecal bacteria renders the polypeptide core susceptible to pancreatic proteases.
...
PMID:In vitro degradation of gastric mucin. Carbohydrate side chains protect polypeptide core from pancreatic proteases. 618 90

The effect of several factors on Escherichia coli K99-plasmid associated agglutination has been studied. The results obtained indicate that Escherichia coli 637 (K99+) mediated red blood cell agglutination is unspecific although the agglutination titres for several erythrocyte species are significantly different. The agglutination is highly stable (at least with sheep red blood cells) to changes in temperature (from 4 degrees C to 37 degrees C), to changes in pH (from 5 to 9) and to the presence or absence of several metallic cations. Treatment of sheep erythrocytes with certain proteolytic enzymes (papain and trypsin) results in a increment in their agglutinability. Also, the extraction of galactose after the removal of sialic acid residues from the oligosaccharides present on the erythrocyte membranes results in a great increment in their agglutinability. On the other hand, only thyroglobulin, mucin, fetuin, and the oligosaccharides extracted from the last two glycoproteins are able to inhibit K99-plasmid mediated sheep red blood cell agglutination.
...
PMID:Study of several factors affecting the agglutinating activity of K99-positive Escherichia coli strains. 637 53

The mucin-release effect of proteinases on airways epithelium was assessed in vitro. Using explants of rabbit tracheal mucosa-submucosa we determined that elastase and alkaline proteinase from Pseudomonas aeruginosa, pancreatic trypsin and elastase and the microbial proteinases subtilisin, thermolysin and pronase, all stimulate mucin release from goblet cells. On the other hand Streptomyces caespitosus proteinase pancreatic chymotrypsin and collagenase fail to trigger mucin release. Bovine trachea and human nasal polyp epithelium also release mucins in response to proteinases. Mucin release activity is dependent on proteolytic activity of enzymes which have a fairly broad, but generally similar, substrate specificity. The cellular mechanism of action is not known. We propose that mucin secretion in response to proteinases represents a useful defence mechanism but also forms the basis for hypersecretory states and airways obstruction in chronic endobronchial inflammatory states.
...
PMID:Proteinases release mucin from airways goblet cells. 639 45

The present study deals with the biochemical properties of high-molecular-weight glycopeptides isolated from the surface of human teratocarcinoma cells. This cell surface material released by mild trypsin digestion from galactose-labeled human teratocarcinoma cells, Tera I and PA1, was digested extensively with pronase. Most of the resulting glycopeptides were large and were excluded from a Sephadex G-50 column. The properties of these large cell surface glycopeptides isolated from Tera I cells have been examined in detail. It is clear from these experiments that they are neither acidic mucopolysaccharides nor mucin-type glycopeptides with short oligosaccharide chains. Although the glycopeptides are hardly hydrolyzed by beta-galactosidase even after prior digestion with neuraminidase, around 30% of the glycopeptides are depolymerized by treatment with endo-beta-galactosidase from Escherichia freundii. The large cell surface glycopeptides from Tera I cells therefore appear to be very similar to the large glycopeptides seen on mouse embryonal carcinoma cells, which have core structures composed of galactose and N-acetylglucosamine. Like the mouse cell glycopeptides, a fraction of the large glycopeptides from these human cells bind to agarose-conjugated fucose-binding proteins and peanut agglutinin.
...
PMID:Biochemical properties of the high-molecular-weight glycopeptides released from the cell surface of human teratocarcinoma cells. 680 82


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

---