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)

Fragments of adult rabbit lung, composed chiefly of terminal airway obtained by a trypsin digestion technique were maintained on collagen-coated cellulose sponges in Ham's F12 medium. Cell-sponge associations were examined with light microscopy, scanning and transmission electron microscopy over a period from 6 to 28 days. After an initial 24- to 48-hour period of cell migration from the airway fragment, sponge matrices became lined with cells suggestive of alveolar macrophages. After one week in culture, cysts appeared to be composed entirely of type 2 epithelial cells. These were characterized by a microvillous apical border and an elaborate junctional complex. The lumen of these cysts contained both myelin-like lamellar configurations and tubular myelin structures such as have been described from pulmonary washings. Consistent with the age of the sponge cultures, one or more cyst types described as young, middle and late could be found simultaneously. Middle aged cysts showed signs of active secretion into the lumen. Late cysts showed changes in the epithelium comprising the cyst wall suggestive of a cell type intermediate between type 1 and type 2 epithelial cells.
...
PMID:Ultrastructure of in vitro type 2 epithelial cell cysts derived from adult rabbit lung cells. 55 27

Cells were isolated from the major arteries of 17-day chick embryos by digestion of the tissue with collagenase and trypsin. The cells, when examined immediately after isolation, exhibited a high degree of viability and they were shown to synthesize and secrete procollagen at a high and constant rate for several hours when incubated in suspension in modified Krebs medium. Continuous labelling of the cells with [(14)C]proline demonstrated a lag of about 30min between the time at which the synthesis of non-diffusible peptide-bound hydroxy[(14)C]proline became linear and the time at which its secretion into the medium became linear. This lag time compares with that of 18min observed for freshly isolated matrix-free cells from embryonic-chick tendon, which synthesize and secrete the same type of collagen. Gel-filtration chromatography and polyacrylamide-gel electrophoresis indicated that the collagenous polypeptides secreted into the medium were in the precursor form, known as procollagen, and that the constituent pro-alpha-chains were linked by interchain disulphide bonds and were also in a triple-helical conformation. Characterization of the secreted procollagen by gel-filtration chromatography, polyacrylamide-gel electrophoresis, DEAE-agarose chromatography, and polyacrylamide-gel electrophoresis of peptides obtained by CNBr cleavage, indicated that the predominant form was type-I procollagen. This work extends the range of freshly isolated matrix-free cell systems, which have been characterized for use in studies on the biosynthesis and secretion of procollagen, and it indicates differences in the rates of secretion of procollagen in different cell types secreting the same type of procollagen.
...
PMID:Synthesis of procollagen by matrix-free cells from embryonic-chick arteries. 59 39

Ehrlich ascites tumour cells contain a neutral protease, capable of solubilising fluorescein-labelled telopeptides from fluorescein-labelled polymeric collagen fibrils. The cells also contain an inhibitor for this enzyme and for trypsin. The enzymically inactive enzyme-inhibitor complex can be dissociated with the mercurial thiol agent, mersalyl, with the consequent regain of enzymic activity. The reactivated neutral protease and also trypsin can be inhibited by addition of thiols such as cysteine, mercaptoethanol and dithiothreitol. Trypsin can be protected from inactivation by the tumor inhibitor by addition of cystine or L-1-tosylamido-2-phenylethyl chloromethyl ketone(TosPheCH2Cl)-inactivated chymotrypsin. The evidence suggests that the inhibitor contains a reactive thiol group which exchanges with one or more significant disulphide bridges in trypsin and the neutral protease, resulting in enzyme-inhibitor complex formation and loss of activity. Similarly, thiols interact with these enzymes resulting in a corresponding loss of enzymic activity. The evidence obtained with Tos-PheCH2Cl-inactivated chymotrypsin, which reactivated previously inhibited trypsin and neutral protease, demonstrates that the active site of the enzyme is not involved in the interaction with the thiol of the inhibitor but that the significant disulphide bond in the enzyme is required for the maintenance of the active site conformation. This disulphide exchange mechanism is therefore a form of reversible allosteric control of proteolytic activity and has been shown to be distinct from the mechanism by which soya bean trypsin inhibitor interacts with trypsin.
...
PMID:Evidence for the inhibition of trypsin by thiols. The mechanism of enzyme-inhibitor complex formation. 62 6

The digestion and absorption of collagen, native and artificially cross-linked, has been examined in the rat and the Gaboon viper, by feeding known quantities and measuring the hydroxy-proline content of the faeces and of the contents of the gut at different levels, and comparing with an unabsorbable marker (polyethylene glycol). Incubation of collagen in vitro with pepsin at 37 degrees C at pH 1.5 followed by trypsin or chymotrypsin converted about 40% into dialysable material.
...
PMID:Digestion of native collagen in the gut. 63 45

The possible participation of proteases in human platelet aggregation was explored using various protease inhibitors and substrates. Protease inhibitors used included naturally occurring inhibitors of serine proteases and synthetic inhibitors that modify the active site of protease. Substrates used were synthetic substrates for the trypsin type as well as for the chymotrypsin type of protease. All these inhibitors and substrates inhibited platelet aggregation and serotonin release induced by ADP, collagen, epinephrine, or thrombin. In ADP- and epinephrine-induced platelet aggregation the second phase of aggregation was most efficiently inhibited. The inhibitors suppressed the formation of malondialdehyde during platelet aggregation. Release by aggregating agents of arachidonate and its metabolites from indomethacin-treated platelets as well as nontreated platelets was also inhibited. The inhibitors apperar to interact with stimulated platelets but not with unstimulated platelets. These observations suggest that the interaction of an aggregating agent with its platelet receptor activates a unique precursor serine protease that in turn activates platelet phospholipase to liberate arachidonic acid (the precursor of the potent platelet aggregating agent thromboxane A2) from platelet phospholipids.
...
PMID:Inhibition of platelet aggregation by protease inhibitors. Possible involvement of proteases in platelet aggregation. 65 19

Trypsin was studied as an aggregating and release-inducing agent with gel-filtered platelets (GFP) and was compared with ADP, epinephrine and collagen. GFP aggregated irreversibly with final concentrations of 0.5-4 microgram/ml trypsin, 1.6-3.2 micrometer ADP, 2.5-5 micrometer epinephrine and 40 microlite 1/ml soluble collagen. Addition of human fibrinogen to the Tyrode-suspending buffer was required for ADP and epinephrine, but was not necessary for trypsin or collagen. Release of (14C)5HT was obtained with trypsin and collagen using the same concentrations as used in aggregation. GFP stored at room temperature for 48 h were still responsive to trypsin and collagen, whereas aggregability and (14C)5HT release induced by ADP and epinephrine were already impaired 5 h after collection of blood. CP-CPK, an ADP-removing reagent, blocked aggregation and release induced by low trypsin concentrations, suggesting that ADP plays an intermediate role in the mechanism by which trypsin activates platelets. Trypsin appears to be a valuable reagent for studying platelet physiology, particulary following storage.
...
PMID:The effect of trypsin and storage on aggregation and release of human gel-filtered platelets. 65 86

Fractionation of the leech (Hirudo medicinalis) body-wall glycoproteins yielded a collagen fraction containing only D-glucose and D-galactose as its carbohydrate constituents. Digestion of the collagen with trypsin and pronase, and alkaline degradation of the resulting glycopeptides, gave a product that contained a disaccharide linked to hydroxylysine. Mild, acid hydrolysis of the N-acetylated glycopeptides yielded a disaccharide consisting of a D-glucose and a D-galactose residue. Various chemical and enzymic reactions of the disaccharide, the glycosyloxylysine, and the glycopeptide fraction indicated that the disaccharide is 2-O-alpha-D-glucopyranosyl-D-galactose, and that this is beta-glycosidically linked to O-5 of the hydroxylysine residue in the collagen.
...
PMID:Isolation of a collagen fraction from the body-wall glycoproteins of the leech (Hirudo medicinalis), and characterization of its carbohydrate--amino acid portion. 66 77

Cell Adhesion Factor, complexed to insoluble collagen-coated tissue culture dishes, is required for the attachment of fibroblasts to this substrate. In solution, the factor has no demonstrable affinity for cells in suspension following trypsin-EDTA removal of cells from monolayer. Cell surface receptors for the factor are present during the assay period since cells allowed to recover for 1 h at 37 degrees C, 4 degrees C or in the presence of 10(-6) M cycloheximide show exactly the same kinetics of adhesion as control cells. It is demonstrated that Cell Adhesion Factor acquires affinity for the cell surface only following its binding to collagen.
...
PMID:Substrate activation of cell adhesion factor as a prerequisite for cell attachment. 68 Oct 24

Human epidermal keratinocytes may be isolated in high yield from 0.1 mm keratotome sections of adult skin by short-term trypsin release. When plated on a collagen-coated plastic surface or on a collagen gel, keratinocytes attach with high efficiencies (greater than 70%) and form confluent, stratified cultures. Cell populations of predominantly basal cells produce proliferative primary cell cultures while populations of basal cells and malpighian cells result in nonproliferative primary cultures. Both nonproliferative and proliferative primary cultures may be subcultured on collagen gels following dispersion by trypsin and EDTA. Methotrexate strongly inhibits proliferative keratinocytes at low concentrations (0.1 microgram/ml) but has no cytotoxic effect on non-proliferative cells. L-serine and dexamethasone increase the multiplication rate of both primary and subcultured human keratinocytes.
...
PMID:Isolation and growth of adult human epidermal keratinocytes in cell culture. 68 86

Samples of the tendons and fascia subjected to the action of amylolytic and proteolytic enzymes (protorysin, trypsin) were examined by scanning electron microscopy. Degradation of the carbohydrate-protein complexes proved to bring about disappearance of the characteristic morphological signs of the collagen fibers. It was shown that a network of thin anastomosing filaments forming a framework connected with the carbohydrate-protein matrix underlay construction of the collagen fibers. As assumed, the net-like structure was a common principle in the structural organization of fibrous connective tissue.
...
PMID:[Role of carbohydrate-protein complexes in the organization of the microstructure of fibrous connective tissue]. 72 21


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

---