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)

125I-Insulin was used as a model mitogen to examine the relationships of mitogen receptor occupancy and exposure in controlling cell replication. Labeled hormone was bound to substratum-attached, confluent fibroblasts with two affinities, K1 approximately equal to 2 X 108 M-1 and K2 approximately equal to 0.8 X 107 M-1. Approximately 9,000 receptors per cell were calculated from a scatchboard plot analysis with 80% of them of the affinity type. Treatment of confluent fibroblasts with 1.0 to 10 microng/ml of trypsin for 10 min increasd the number of exposed K2 sites by a factor of 2 to 3. Culturing the fibroblasts in the absence of serum for 12 to 24 hr also increased the quantity of exposed K2 sites to 60,000 per cell. The addition of unlabeled insulin to untreated, trypsin-treated, or serum-starved fibroblasts resulted in a stimulation of 2-deoxyglucose transport and thymidine incorporation activity that was proportional to the observed level of 125I-insulin binding. The quantity of exposed insulin receptors on uninfected fibroblasts decreases as the cell culture density increases. Hormone binding to B77 virus-transformed fibroblasts also decreases with culture density but plateaus at a density of 6 X 105 cells/plate. This resulted in a 2- to 3-fold difference in the level of exposed receptors between the uninfected and virus-transformed cells in confluent cultures, and proportionally higher rates of sugar transport and thymidine incorporation activity. Trypsin treatment and 12 hr of growth in the absence of serum did not result in an increase in the level of recepto exposure in the virus-transformed cells. The results of this study suggest that the pleotypic events associated with the stimulation of cell replication as represented by sugar transport and DNA synthesis are dependent upon and proportional to mitogen receptor occupancy. The control of cell replication, however, appears to be linked by a presently unknown mechanism with the degree of exposure of mitogen recipotrs. Receptor concentration is high and is similar in rapidly growing uninfected and virus-transformed cells, but the subsequent decrease observed with an increase in culture density reaches an early plateau for the transformed cells. This difference in exposed receptors could provide the growth advantage that is the hallmark of transformed cells.
...
PMID:Extent of mitogen receptor occupancy and modulation of mitogen receptor exposure: possible mechanisms for the regulation of cell growth. 19 33

31P nuclear magnetic resonance (NMR) spectra of human low density lipoprotein (LDL) has been obtained and the major phospholipid components identified. Analysis of the spectra revealed two phospholipid environments: one occupied by 4/5 of the phospholipid with high resolution resonances possessing properties similar to phospholipids in vesicles, and a second occupied by 1/5 of the phospholipid with broad lines indicative of immobilization. Limited trypsin treatment of the particle cleaved all of the B peptide into smaller molecular weight peptides which remained with the particle. Trypsin-treated LDL eluted from a Sepharose CL-6B column similarly to native LDL so that the modified particle remained intact. 31P NMR spectra of trypsin-treated LDL showed little or no immobilized phospholipid. The immobilization in the native LDL particle is attributed to lipid-protein interactions between 1/5 of the phospholipid and the B peptide.
...
PMID:Phospholipid-protein interactions in human low density lipoprotein detected by 31P nuclear magnetic resonance. 19 35

Mitoplasts, that is, mitochondria freed from their outer membranes, were prepared from pig heart. Sonication induced an inversion of these mitoplasts, giving inside-out vesicles. Added cytochrome c can be bound much better to mitoplasts than to sonicated vesicles; addition of trypsin increased adenosinetriphosphatase (ATPase) (ATP phosphohydrolase; EC 3.6.1.3) activity of sonicated vesicles without significantly affecting that of the mitoplasts. Since the site of fixation of cytochrome c was located on the outer side of the inner mitochondrial membrane and since the protein inhibitor of the mitochondrial ATPase is present on the inner face of the inner membrane and is very sensitive to trypsin, it can be concluded that mitoplasts are mainly oriented as normal mitochondria while sonicated vesicles are mainly inverted. Trypsin treatment can abolish the oligomycin sensitivity of ATPase activity of either mitoplasts or sonicated vesicles. However, trypsin induced the solubilization of the soluble F(1)-ATPase of sonicated vesicles while the ATPase activity remained with the mitoplasts after trypsin action. Therefore, trypsin destroyed the oligomycin effect by rupturing the liaison between F(1) and the membrane in sonicated vesicles. On the other hand, the effect of trypsin on mitoplasts must be attributed to the hydrolysis of a protein located near the outer surface of the inner membrane that is at least structurally involved in the oligomycin sensitivity of the ATPase complex.
...
PMID:Location of protein(s) involved in oligomycin-induced inhibition of mitochondrial adenosinetriphosphatase near the outer surface of the inner membrane. 20 Sep 6

Trypsin-treatment of human fat cells results in the potentiation of the lipolytic response and the cAMP accumulation induced by theophylline (5 . 10(-4) M) but not of those induced by theophylline (5 . 10(-3) M). The amount of cAMP formed after exposure to theophylline (5 . 10(-3) M) plus norepinephrine (5 . 10(-6) M) remains, however, 2.6 fold higher in trypsin-treated human fat cells than in the control ones.
...
PMID:Modification of theophylline-induced lipolysis in human fat cells after trypsination. 20 72

The nature of the binding of C. parvum organisms to the surface of glass-adherent mouse peritoneal exudate cells in vitro was studied using pretreatment of the cells with various enzymes and periodate. Trypsin, pronase, beta-galactosidase, phospholipases A, C and D and periodate all caused a decrease in binding to 40-60% of untreated control. Neuraminidase led to a 30% increase in binding. The binding ability returned to normal after 1 h at 37 degrees in culture medium following exposure to all the enzymes apart from pronase, which apparently could not be removed effectively by washing. The presence of EDTA in the medium inhibited recovery from treatment with trypsin and beta-galactosidase; return to normal after exposure to phospholipases A, C and D was slightly affected, whereas recovery from treatment with neuraminidase was unaffected. Cells that had been exposed to periodate did not regain normal binding ability after 1 h in tissue culture medium but the effect could be reversed chemically by treatment with borohydride. The role of different plasma membrane components in non-specific cellular recognition is discussed.
...
PMID:Binding of microorganisms to the macrophage plasma membrane; effects of enzymes and periodate. 20 34

We studied the synthesis of excreted DNA sequences and their release from phytohemagglutinin-stimulated human peripheral blood lymphocytes under conditions permitting optimal cell growth. Cells were labeled by constant exposure to low specific activity [3H]thymidine. Excreted DNA sequences were synthesized during the period of logarithmic cell growth and moved slowly from the high molecular weight chromosomal DNA fraction into the low molecular weight cell DNA fraction (Hirt supernate) from which they could be specifically released by treating the cells briefly with small amounts of various proteases; 1 microgram/ml trypsin for 5 min was optimal. On day 5 of culture, 13.3 +/- 6.9% of the total cellular acid-precipitable [3H]thymidine was released by this treatment. Trypsin-induced release was partially and reversibly inhibited by incubating the cells for 16 h with 5 mM dibutyryl-cyclic AMP. Cells incubated in the absence of divalent cations spontaneously released this Hirt supernatant DNA; after maximal release had occurred under these circumstances, additional trypsin treatment caused no further release of DNA. Trypsin-induced DNA release could be completely and reversibly inhibited by incubating the cells in the presence of 10 mM calcium. Trypsin-released DNA was isolated and analyzed by reassociation kinetics. A major component, representing 54% of the DNA, reassociated with a C0t1/2 of 68 mol.s/liter (the value at which DNA association is 50% complete). The reassociation of this DNA was studied in the presence of an excess of DNA isolated from stimulated lymphocytes on day 3 in culture, and in the presence of an excess of resting lymphocyte DNA. The high molecular weight fraction of day-3 cell DNA contained three times more copies of the trypsin-released DNA major component as compared to resting lymphocyte DNA. Hirt supernatant DNA isolated from day-5 stimulated lymphocytes reassociated in an intermediate component representing 34% of the DNA with a Cot1/2 of mol.s/liter; after cells were treated with trypsin, this component could no longer be identified in the Hirt supernatant fraction, presumably because it had been released into the incubation medium. These data describe a quantitatively reproducible system with which synthesis and release of excreted DNA sequences can be studied.
...
PMID:Selective release of excreted DNA sequences from phytohemagglutinin-stimulated human peripheral blood lymphocytes. Effects of trypsin and divalent cations. 20 31

1. A latent neutral proteinase was found in culture media of mouse bone explants. Its accumulation during the cultures is closely parallel to that of procollagenase; both require the presence of heparin in the media. 2. Latent neutral proteinase was activated by several treatments of the media known to activate procollagenase, such as limited proteolysis by trypsin, chymotrypsin, plasmin or kallikrein, dialysis against 3 M-NaSCN at 4 degrees C and prolonged preincubation at 25 degrees C. Its activation often followed that of the procollagenase present in the same media. 3. Activation of neutral proteinase (as does that of procollagenase) by trypsin or plasmin involved two successive steps: the activation of a latent endogenous activator present in the media followed by the activation of neutral proteinase itself by that activator. 4. The proteinase degrades cartilage proteoglycans, denatured collagen (Azocoll) and casein at neutral pH; it is inhibited by EDTA, cysteine or serum. Collagenase is not inhibited by casein or Azocoll and is less resistant to heat or to trypsin than is the proteinase. Partial separation of the two enzymes was achieved by gel filtration of the media but not by fractional (NH4)2SO4 precipitation, by ion exchange or by affinity chromatography on Sepharose-collagen. These fractionations did not activate latent enzymes. 5. Trypsin activation decreases the molecular weight of both latent enzymes (60 000-70 000) by 20 000-30 000, as determined by gel filtration of media after removal of heparin. 6. The latency of both enzymes could be due either to a zymogen or to an enzyme-inhibitor complex. A thermostable inhibitor of both enzymes was found in some media. However, combinations of either enzyme with that inhibitor were not reactivated by trypsin, indicating that this inhibitor is unlikely to be the cause of the latency.
...
PMID:The simultaneous release by bone explants in culture and the parallel activation of procollagenase and of a latent neutral proteinase that degrades cartilage proteoglycans and denatured collagen. 20 18

Rabbits were injected intraarticularly three times with 0.5 ml of 10, 50 or 100 mg% purified rheumatoid synovial collagenase or with identical amounts of trypsin. 18 hours after the last injection the collagenase-injected animals showed distinct cellular exudation into the synovial fluid and acute arthritis; one week later there was a decrease of the cell count in the synovial fluid and appearance of proliferative synovitis, while 3 weeks later there was no exudation and less chronic inflammation but distinct fibrosis of the synovium. A direct action of collagenase on the connective tissue components would seem to be responsible for these changes. No pathologic alteration of the cartilage was observed. Trypsin-injected control animals showed negligible cellular exudation and no pathologic alteration of the synovium.
...
PMID:Collagenase-induced experimental arthritis. 21 3

Trypsin, thrombin, and ionophore A23187 activate phospholipid breakdown of platelets that have been labeled with [(14)C]arachidonate, releasing their cyclooxygenase and lipoxygenase products. Intact platelets can also very effectively directly degrade low concentrations of exogenous, free [(14)C]arachidonate. Pretreatment of platelets with trypsin, thrombin, or ionophore A23187 for a minimum time of 30 sec leads to complete inactivation of cyclooxygenase activity, as demonstrated by subsequent exposure to [(14)C]arachidonate. Lipoxygenase activity is lost after 5 min. The thrombin-induced inactivation of cyclooxygenase and lipoxygenase is prevented by cyclic AMP (which inhibits the stimulated activity of phospholipase A(2)), although cyclic AMP does not affect the degradation of exogenous [(14)C]arachidonate. Exposure of platelets labeled with [(14)C]arachidonate to unlabeled arachidonate under conditions that lead to use of the latter also results in a similarly rapid inhibition of cyclooxygenase activity, as determined by subsequent challenge with thrombin. Under these conditions lipoxygenase activity is much less markedly inactivated. The arachidonate-induced inhibition of cyclooxygenase activity is not prevented by cyclic AMP. Trypsin does not induce platelet aggregation, and platelets whose cyclooxygenase activity has been inactivated are intact insofar as they are still able to undergo aggregation. These studies demonstrate that operation in intact platelets of the cyclooxygenase pathway, through use of endogenous or exogenous substrate, leads to a very rapid, irreversible inactivation of this enzyme. The lipoxygenase pathway is also progressively impaired, but much less rapidly than the cyclooxygenase enzyme and much less markedly on use of exogenous compared to endogenous substrate. The possible consequences of these physiological processes of spontaneous inactivation are considered.
...
PMID:Rapid inactivation of cyclooxygenase activity after stimulation of intact platelets. 21 91

In order to elucidate the cytochemical properties of the membranous structure between enamel and ameloblasts of the rat incisor at the maturation stage, chromic phosphotungstic acid (Cr-PTA) and periodic acid-silver methenamine (PA-silver) techniques for electron microscopy were employed in combination with a digestion test with hyaluronidase, neuraminidase, collagenase or trypsin. Also, acid phosphatase activity of ameloblasts at the maturation stage was examined with a modified GOMORI's metal salt method. An intensely Cr-PTA reactive band approximately 0.1 micron thick appeared along the surface layer of enamel at the transitional stage, and at the very beginning of the maturation stage another intensely Cr-PTA reactive band which was seen by uran-lead stain to be a delicate electron-dense membranous structure appeared as well between enamel and ameloblasts. A lot of cytoplasmic small vesicles or tubular structures, both intensely reactive to Cr-PTA, were observed near the apical membranes of the overlying ameloblasts indicating that those organelles must have been responsible for the secretion of the latter band. Acid phosphatase activity was clearly demonstrated at Cr-PTA reactive large vesicles in the cytoplasm of those cells. The PA-silver staining technique manifested a band heavily deposited with silver grains along the surface layer of enamel, i.e., where the former band existed, but showed no particular reaction at the latter, the band-like layer between enamel and ameloblasts. Hyaluronidase or neuraminidase treatment remarkably decreased the Cr-PTA reaction of the latter band. Trypsin or collagenase treatment, on the other hand, not only eliminated the Cr-PTA reaction but digested the band itself. These results suggest that the membranous structure between enamel and ameloblasts of a rat incisor is not so-called enamel cuticle but a basal lamina produced by overlying ameloblasts and that the basal lamina contains collagenous components even though it lies on enamel.
...
PMID:Cytochemical studies of ameloblasts and the surface layer of enamel of the rat incisor at the maturation stage. 21 3


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

---