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)

Treatment of phosphorylating fragments of bacterial membrane from Micrococcus lysodeikticus with trypsin leads to increase ATPase activity. As a result of this treatment, the membrane fragments acquire the ability to transform the ATP energy into transmembrane difference in potential. Dithiothreitol has a similar effect to that of trypsin on the membrane fragments from M. lysodeikticus. Dicyclohexylcarbodimide inhibits ATPase of the membrane fragments of M. lysodeikticus, and also the ATPase-reaction-coupled generation of membrane potential. It has been suggested that the increased ATPase activity of membranes from M. lysodeikticus during treatment with trypsin and dithiothreitol is connected with the effect of these agents on the protein inhibitor of ATPase.
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PMID:Membrane-reversible H+-ATPase from Micrococcus lysodeikticus. 0 6

Properties of carboxypeptidase A of cultured skin fibroblasts from control and cystic fibrosis patients were studied using alpha-N-carbobenzoxy-L-glutamyl-L-tyrosine as substrate. Carboxypeptidase A was inhibited by thiomersal, cyanide, iodoacetate and N-ethylmaleimide in a similar manner for control and cystic fibrosis fibroblasts. Both trypsin and dithiothreitol treatment activated the enzyme, but 1,10-phenanthroline inhibited only in the presence of dithiothreitol. Both Zn2+ and Co2+ reversed this inhibition. Trypsin treatment of carboxypeptidase A produced a form of the enzyme having a higher KM value for both control and cystic fibrosis fibroblasts. Dithiothreitol treatment of control fibroblasts resulted in a form with similar properties to the trypsin activated form, but cystic fibrosis fibroblasts yielded a variant form with even higher KM and Vmax values. Since other properties were similar, it seems likely that this difference reflected binding of a molecule to the enzyme rather than of a defect in the enzyme.
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PMID:Carboxypeptidase A activity of cultured skin fibroblasts and relationship to cystic fibrosis. 66 47

Changes in the topography of the sea urchin egg after fertilization were studied by scanning and transmission electron microscopy. Strongylocentrotus purpuratus eggs were treated with dithiothreitol to modify the vitelline layer and to prevent formation of a fertilization membrane. Dithiothreitol treatment caused the microvilli to become more irregular in shape, length, and diameter than those of untreated eggs. The microvilli were similarly modified by trypsin treatment. This effect did not appear to be due to disruption of cytoskeletal elements beneath the plasma membrane, for neither colchicine nor cytochalasin B altered microvillar morphology. Thus, it appears that the vitelline layer may act in the maintenance of surface form of unfertilized eggs. Since dithiothreitol-treated eggs did not elevate a fertilization membrane, scanning electron microscopy could be used to directly observe modifications in the egg plasma membrane after fertilization. The wave of cortical granule exocytosis initiated at the point of attachment of the fertilizing sperm was characterized by the appearance of pits that subsequently opened, releasing the cortical granule contents and leaving depressions upon the egg surface. The perigranular membranes inserted during exocytosis were seen as smooth patches between the microvillous patches remaining from the original egg surface. This produced a mosaic surface with more than double the amount of membrane of unfertilized eggs. The mosaic surface subsequently reorganized to accommodate the inserted membrane material by elongation of microvilli. Blebs and membranous whorls present before reorganization suggested the existence of an unstable intermediate state of plasma membrane reorganization. Exocytosis and mosaic membrane formation were not blocked by colchicine or cytochalasin B, but microvillar elongation was blocked by cytochalasin B treatment.
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PMID:Changes in the topography of the sea urchin egg after fertilization. 98 32

The sources of optical retardation changes and light scattering changes occurring during the action potential propagation of lobster giant axons have been investigated. A technique has been developed for resolving the total transmitted-light intensity change into a retardation change component, dI-r, and a forward direction light scattering change, dI-s. Trypsin, pronase, neuraminidase and hyaluronidase all reduce the magnitude of dI-r without diminishing the action potential, probably by cleaving charged saccharides. Dithiothreitol has no effect. This suggests that glycoproteins and hyaluronic acid polymers at the surface of the axon are involved in the optical responses, either by being passively realigned or by contributing to compression and expansion forces as the membrane electric field changes. Large dI-s responses are generated by trypsin and pronase treatment. The modifying effects of these proteases may be due to modification of the membrane or to increases in the refractive index of the medium surrounding the axon, since similar large dI-s, responses are produced by increasing the refractive index with sucrose. Since large reductions in dIr can be produced without concurrent reductions in the action potential, a significant portion of the optical retardation responses cannot be attributable to structural changes that are causally related to membrane ionic permeability changes during the action potential.
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PMID:Modification of optical responses associated with the action potential of lobster giant axons. 112 18

We have reported earlier that cholinephosphotransferase (EC 2.7.8.2) is present in both mitochondria and microsomes of fetal guinea pig lung. This study was designed to compare the properties of mitochondrial and microsomal cholinephosphotransferase in fetal guinea pig lung. Various parameters, such as substrate specificity, Km values, sensitivity to N-ethylmaleimide, dithiothreitol and trypsin were measured. Both showed significant preference for unsaturated diacylglycerols over saturated diacylglycerols. Data on Km and Vmax indicate that the affinity of this enzyme for different diacylglycerols varies between the two forms. The ID50 values for N-ethylmaleimide were 20 mM and 12.5 mM for the mitochondrial and microsomal form of the enzyme, respectively. Dithiothreitol showed an inhibitory effect on both; however, the mitochondrial form was inhibited less than the microsomal form. The effects of N-ethylmaleimide and dithiothreitol on both forms of enzyme indicated that the microsomal cholinephosphotransferase requires a higher concentration of -SH for its activity than the mitochondrial enzyme does. The enzyme was inhibited by trypsin in both mitochondria and microsome under isotonic condition suggesting that this enzyme is on the outside of the membrane in both endoplasmic reticulum and mitochondria.
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PMID:Study of properties of cholinephosphotransferase from fetal guinea pig lung mitochondria and microsomes. 165 Apr 26

Arginine-specific ADP-ribosyltransferase from rabbit skeletal muscle sarcoplasmic reticulum was solubilized as the active form with trypsin. The enzyme was partially purified by subsequent chromatography, successively on DE-52, Con A-Sepharose and Sephadex G-75. An approximately 2,000-fold purification was achieved from the 105,000 x g supernatant of trypsin-treated membrane with a recovery of 2.8%. Dithiothreitol, which activates hen liver nuclear ADP-ribosyltransferase, inhibited the enzyme.
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PMID:Arginine-specific ADP-ribosyltransferase from rabbit skeletal muscle sarcoplasmic reticulum is solubilized as the active form with trypsin: partial purification and characterization. 250 33

Oxytocin initiates its insulin-like action in adipocytes through oxytocin-specific receptors. We have studied binding and structural properties of these receptors with the radioligand [3H]oxytocin. Steady-state binding was reached after 45 min, at 21 degrees C, and 10 min at 37 degrees C. Scatchard analyses of equilibrium binding data indicated a single class of oxytocin binding sites at 21 degrees C (KD = 3.3 nM, RT = 6 X 10(4) sites/cell) and 2 binding sites at 37 degrees C (KD = 1.5 nM, RT = 6 X 10(4) sites/cell; and KD = 20 nM, RT = 30 X 10(4) sites/cell). Insulin, insulin-like growth factor I, and epidermal growth factor increased oxytocin binding (approximately 20-40%), whereas adenosine, a regulator of oxytocin action, did not affect oxytocin binding. Binding activity of oxytocin was impaired by pretreatment of the hormone or adipocytes with dithiothreitol. Dithiothreitol treatment of adipocytes preferentially inactivated high-affinity binding sites. N-ethyl maleimide inhibited oxytocin binding in adipocytes more than dithiothreitol. In contrast to the inhibitory effects of dithiothreitol and N-ethyl maleimide, proteases (trypsin, chymotrypsin and papain) were not able to inhibit fat cell binding activity. These results suggested that in isolated adipocytes: there are high-affinity and low-affinity receptors, but the low-affinity receptors are absent at 21 degrees C; the binding of oxytocin can be regulated by insulin, and growth factors; and the oxytocin receptors contain disulfide bridges and free thiols that are essential for the maintenance of oxytocin binding.
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PMID:Binding and structural properties of oxytocin receptors in isolated rat epididymal adipocytes. 281 58

Proteinase II, a high-molecular-mass proteinase previously identified in white croaker skeletal muscle, was purified to apparent homogeneity by DEAE-Sephacel, phenyl-Sepharose CL 4B, and Sephacryl S-300 chromatographies. Under denaturing conditions, the enzyme dissociated into a cluster of subunits with Mr ranging from 18,000 to 26,000 and a large subunit with a Mr 60,000. The proteinase was able to hydrolyze N-terminal-blocked 4-methyl-7-coumarylamide substrates having either an aromatic amino acid (chymotrypsin-like activity) or an arginine residue (trypsin-like activity) adjacent to the fluorogenic group. The trypsin-like activity of the enzyme was inhibited by fatty acids and sodium dodecyl sulfate, whereas the chymotrypsin-like activity was stimulated by those compounds but inhibited by nonionic and cationic detergents. Several thiol reagents inhibited both proteinase II activities. However, leupeptin and Cu2+ strongly inhibited its trypsin-like activity but only slightly affected its chymotrypsin-like activity. Dithiothreitol stimulated both activities, but at different extents and in different concentration ranges. These results suggest that the enzyme is multicatalytic, having at least two different active sites.
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PMID:Multicatalytic proteinase in fish muscle. 321 72

A protein kinase was solubilized from whole vaccinia virions by using a solution containing deoxycholate, dithiothreitol, and sodium or potassium chloride. The released enzyme was completely dependent on Mg(2+) and was greatly stimulated by added basic proteins such as protamine or histones. Dithiothreitol was also stimulatory, whereas GTP, CTP, UTP, and P(i) at concentrations equimolar with ATP had little or no effect. Attempts to purify the protein kinase were initially unsuccessful, leading us to consider that either the enzyme was extremely labile or that two readily separable components were required for activity. The observation that the material extracted with NP-40 detergent during the preparation of viral cores stimulated the protein kinase activity of the intact cores supported the second possibility. As the protein kinase, now solubilized from viral cores, was passed through successive DEAE-cellulose columns, it became increasingly dependent for activity on addition of the NP-40 extract. A 30- to 40-fold stimulation of protein kinase activity, which afforded recovery of essentially all starting activity, could be effected by addition of the NP-40 extract to the partially purified enzyme. The NP-40 extract was shown to contain a heat stable, trypsin-sensitive protein, whose action could not be duplicated by cyclic nucleotides.
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PMID:Protein kinase activity from vaccinia virions: solubilization and separation into heat-labile and heat-stable components. 477 67

1. Acid proteinase from rabbit liver lysosomes was purified about 1000-fold, on a protein basis. 2. The purification procedure involved isolation of a lysosomal-mitochondrial pellet and conversion of this into an acetone-dried powder. 3. The enzyme was extracted with an acidic buffer and subjected to column chromatography with DEAE-Sephadex and Sephadex G-100. 4. The molecular weight of the enzyme was 50000-52000. 5. Maximal activity against haemoglobin was obtained at pH3.2; serum albumin was attacked, but very much more slowly. 6. Several possible inhibitors of the enzyme were tested. Thiol-blocking reagents, several inhibitors of trypsin and chymotrypsin, and a chelating agent were without effect. 7. The enzyme was competitively inhibited by 3-phenylpyruvic acid at low concentrations. 8. Dithiothreitol caused rapid inactivation of the enzyme at pH8. 9. It is concluded that this enzyme is a form of cathepsin D, which may be widely distributed in lysosomes.
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PMID:Lysosomal acid proteinase of rabbit liver. 605 10


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