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)

Amphipathic enzymes, invertase (EC 3.2.1.26), 8-amylase (EC 3.2.1.3), and alkaline phosphatase (EC 3.1.3.1), were purified from the rat small intestinal mucosa as trypsin and Triton forms, the catalytic and regulatory characteristics of which were compared in rats and in drosophila. Differences in the catalytic propertiis of the two enzyme forms were demonstrated, which suggested that the hydrophobic part of the enzyme was involved in maintaining optimal conformation of the catalytic part. Many modifiers have beenfound to influence the Triton rather than the trypsin form of the enzyme. It is therefore suggested that the hydrophobic sub-units of the enzymes might be involved in transmitting information from the cytoplasm into the external surface of the membrane, the cell in this way regulating the activity of surface enzymes. If this is indeed the case, it is suggested that the hydrophobic part performs functions not only of external but also of internal regulation.
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PMID:Catalytic and regulatory properties of the Triton and trypsin forms of the brush border hydrolases. 4 Aug 47

1. The oligomycin-sensitive ATPase activity of submitochondrial particles of the glycerol-grown "petite-negative" yeast: Schizosaccharomyces pombe is markedly stimulated by incubation at 40 degrees C and by trypsin activations are treatment. Both increased in Triton-X 100 extracts of the submitochondrial particles. 2. A trypsin-sensitive inhibitory factor of mitochondrial ATPase with properties similar to that of beef heart has been extracted and purified from glycerol-grown and glucose-grown S. pombe wild type, from the nuclear pleiotropic respiratory-deficient mutant S. pombe M126 and from Saccharomyces cerevisiae. 3. ATPase activation by heat is more pronounced in submitochondrial particles isolated from glycerol-grown than from glucose-grown S. pombe. An activation of lower extent is observed in rat liver mitochondrial particles but is barely detectable in the "petite-positive" yeast: S. cerevisiae. No activation but inhibition by heat is observed in the pleitotropic respiratory-deficient nuclear mutant S. pombe M126. 4. The inhibition of S. pombe ATPase activity by low concentrations of dicyclohexylcarbodiimide dissapears at inhibitor concentrations above 25 muM. In Triton-extract of submitochondrial particles net stimulation of ATPase activity is observed at 100 muM dicyclohexylcarbodiimide. The pattern of stimulation of ATPase activity by dicyclohexylcarbodiimide in different genetic and physiological conditions parallels that produced by heat and trypsin. A similar mode of action is therefore proposed for the three agents: dissociation or inactivation of an ATPase inhibitory factor. 5. We conclude that "petite-positive" and "petite-negative" yeasts contain an ATPase inhibitor factor with properties similar to those of the bovine mitochondrial ATPase inhibitor. The expression of the ATPase inhibitor, measured by ATPase activation by heat, trypsin or high concentrations of dicyclohexylcarbodiimide, is sensitive to alterations of the hydrophobic membrane environment and dependent on both physiological state and genetic conditions of the yeast cells.
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PMID:Physiological and genetic modifications of the expression of the yeast mitochondrial adenosine triphosphatase inhibitor. 12 68

Protein composition of cardiac sarcolemmal membranes was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Membranes were observed to contain about 20 polypeptide bands ranging from 18000 to 200 000 dalton mass. Out of these, six bands were prominent and together comprised 57% of the membrane protein. When sarcolemmal membranes, phosphorylated by [gamma-(32)P] ATP in the presence of Ca(2+) or Na+ with and without K+, were fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis at pH 2.4, the band III region (Mr 105 000) of gels was found to contain active sites of monomeric Ca-ATPase and (Na,K)ATPase. Bands I (Mr greater than 200 000), II (Mr 150 000), III (Mr 105 000), and VI (Mr 47 000) were accesible to trypsin; the extent of proteolysis was dependent on the time of exposure to, and the concentration of, trypsin (i.e, ratio of sarcolemmal protein/trypsin). Addition of molar sucrose protected sarcolemmal proteins from the tryptic proteolysis. Calcium transport was reduced by the action of trypsin; the degree of reduction was influenced by the time of exposure of membranes to trypsin as well as the concentration of trypsin. (Mg,Ca)ATPase activity, on the other hand, was elevated moderately at lower concentration and reduced at higher concentration of trypsin. Treatment with phospholipase C cium transport and (Mg,Ca)ATPase activity; electrophoretic patterns were unaffected by this treatment. Addition of lecithin to phospholipase C treated membranes produced a moderate increase in calcium transport. Exposure to Triton X-100 (1%) specifically solubilized three protein bands (Mr90 000, 67 000, and 57 000), whereas exposure to deoxycholate (1%) preferentially solubilized high-molecular-weight proteins, including band III (Mr 105 000); Lubrol-PX (1%) caused nonspecific solubilization of proteins, although the extent of solubilization with Lubrol-PX was considerably less than with either Triton or deoxycholate.
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PMID:Protein analysis of cardiac sarcolemma: effects of membrane-perturbing agents on membrane proteins and calcium transport. 21 4

The structural polypeptides of egg grown mumps virus were analysed by SDS-polyacrylamide-slab-gel electrophoresis. Mumps virions contained eight major polypeptides with mol. wt. of 75, 73, 71, 61, 47, 44, 42 and 40 X 10(3). The 75 K and 61 K polypeptides were glycosylated. In virions treated with pronase and trypsin, the 75 K glycoprotein was removed more readily from the virus than the 61 K glycoprotein. The gradual removal of the 75 K glycoprotein was paralleled by a decrease of haemagglutinating activity. The large glycoprotein was cleaved into a 40 K glycoprotein by trypsin treatment. Pronase and trypsin treatment also removed the smallest 40 K non-glycosylated polypeptide. Thus this polypeptide appears to be located on the outside of the virion and probably represents a cleavage product of the large glycoprotein. Treatment of virions with 2% Triton-X 100 under alkaline conditions in the absence or presence of 2 M-KCl solubilized the two glycoproteins and a fraction of the 71 and 44 K polypeptides, but not the 73 and 47 K polypeptides. The two smallest polypeptides were solubilized by treatment with 2% Triton X-100 in the presence of 2 M-KCl. Since the 40 K polypeptide was interpreted to represent a cleavage product of the large surface glycoprotein the 42 K polypeptide was proposed to represent the membrane protein of mumps virus. The 44 K polypeptide co-migrated with Vero cell actin. The nature of the 47 K polypeptide could not be determined, but it is probably located in the central part of the virus. The 73 K polypeptide and in some experiments also the 71 K polypeptide were found in purified nucleocapsid preparations. It is concluded that mumps virus has a general polypeptide composition similar to other paramyxoviruses. However, the molecular weights of the different polypeptides of mumps virus differ markedly from the corresponding polypeptides in Newcastle disease virus and Sendai virus.
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PMID:Structural polypeptides of mumps virus. 21 49

Bull sperm that had been extracted with 0.2% Triton X-100 could be reactivated with ATP, and their movement closely resembled the motion of intact live sperm. Their motility required the presence of ATP, magnesium, and a medium of suitable salt concentration and pH. When Triton-extracted bull sperm were digested breifly with trypsin at pH 9.0, they appeared to reatin most of their normal structure, but subsequent exposure of the digested sperm to ATP caused a disintegration by light microscopy, using dark-field illumination, combined with an electron microscope study of preparations of the disintegrated sperm, demonstrated the presence of an active sliding mechanism of filament interaction in bull spermatozoa. Human sperm subjected to the same procedures showed similar patterns of reactivation and of disintegration.
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PMID:Adenosine triphosphate-induced motility and sliding of filaments in mammalian sperm extracted with Triton X-100. 23 18

The biosynthesis in vivo of rat intestinal sucrase-isomaltase [a complex of sucrose alpha-glucohydrolase, EC 3.2.1.48, and oligo-1,6-glucosidase (dextrin 6-alpha-D-glucanohydrolase), EC 3.2.1.10] has been studied by following the incorporation of L-[6-(3)H]fucose into the enzyme with time. Immunoprecipitation of sucrase-isomaltase from Triton-X-100-solubilized Golgi or basolateral membranes and subsequent polyacrylamide gel electrophoresis revealed the presence of an immunoreactive glycoprotein with an apparent molecular weight approximately twice that of the separated sucrase-isomaltase subunits, but no active subunits were found in these membranes. This glycoprotein was also found in the microvillus membrane in addition to the subunits of sucrase-isomaltase. Kinetic studies showed a maximal labeling of this glycoprotein in Golgi membranes at 15 min, in basolateral membranes at 30 min, and in microvillus membranes at 45 min and a half-life of less than 30 min in each membrane. However, the radioactivity of the sucrase-isomaltase subunits in the microvillus membrane reached a plateau after 60 min. These data suggest that sucrase-isomaltase is synthesized as a one-chain polypeptide precursor that is split into the subunits after its transfer to the microvillus membrane. Elastase (EC 3.4.21.11), but not trypsin (EC 3.4.21.4) or alpha-chymotrypsin (EC 3.4.21.1), split the putative precursor into two polypeptides that had electrophoretic behaviors similar to those of the active enzyme subunits. These studies suggest that pancreatic proteases may play an important role in the late posttranslational processing of sucrase-isomaltase in vivo.
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PMID:Biogenesis of intestinal plasma membrane: posttranslational route and cleavage of sucrase-isomaltase. 29 33

1. The serum proteinase inhibitors alpha 1-antitrypsin, alpha 2-macroglobulin, inter-alpha-trypsin inhibitor and C1-esterase inhibitor were found not to affect the catalytic activity of human enterokinase, whereas bovine trypsin activity was modified essentially as expected. Enterokinase was also not inhibited by Trasylol (trypsin inhibitor from bovine lung) or bovine pancreatic trypsin inhibitor. No other component in human or mouse serum complexing with enterokinase was identified. 2. Human enterokinase administered intravenously into mice was rapidly cleared from the circulation with a half-life of 2.5 min. This removal was not the result of the difference in species, since partially purified mouse enterokinase was cleared at the same rate as the human enzyme. Clearance was mediated by recognition of the carbohydrate portion of enterokinase and not through specific recognition of its catalytic site. Immunofluorescent staining showed that the enzyme accumulated in the liver. Attempts to block the clearance by the simultaneous infusion of competing glycoproteins suggested that enterokinase was taken up by hepatocytes. Of the glycoproteins tested only two, human lactoferrin (terminal fucosyl alpha 1 leads to 3 N-acetylglucosamine) and bovine asialo-fetuin (terminal galactosyl beta 1 leads to 4 N-acetylglucosamine) were weakly competitive. Two inhibitors of endocytosis, Intralipid and Triton WR1339, failed to delay the removal of enterokinase. It is proposed that enterokinase is cleared from the circulation by an as yet uncharacterized hepatocyte receptor.
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PMID:Identification of a defence mechanism in vivo against the leakage of enterokinase into the blood. 39 51

About 30% of the proteins of adherent cultured chick embryo fibroblasts are not solubilized by the non-ionic detergent Triton X-100 and remain firmly attached to the substratum. The insoluble residue contains a considerable part of the cell's cytoskeleton and its major constituents are large external transformation-sensitive (LETS) protein, the heavy chain of myosin, a 52,000 molecular weight protein and actin. Kinetic studies reveal that cytoskeleton insolubility in Triton is acquired either concurrently with cell adhesion or very closely with it. Neither cell adhesion nor binding of the Triton cytoskeleton to the substratum require de novo synthesis of protein. In the attempt to assess the role of LETS protein in cytoskeleton attachment, we find that trypsin-detached cells rapidly acquire Triton-insoluble cytoskeleton although their LETS protein content is about 15--20% of its level in long-term cultures. Removal of the great majority of LETS molecules of adherent cultures by either urea or trypsin treatment does not affect the relative amount or composition of the anchored cytoskeletal proteins. Also, LETS protein of cultures exposed to cycloheximide for extended periods of time, is reduced to 10% of its maximum amount without much affecting the attachment and composition of the cytoskeleton. It is deduced that the great majority of LETS protein is not required for the attachment of the Triton cytoskeleton to the substratum.
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PMID:Cell adhesion and acquisition of detergent resistance by the cytoskeleton of cultured chick fibroblasts. 57 36

Microvillous vesicles isolated from rabbit small intestine showed a trilaminar membrane with a rather smooth surface, which was apparently not affected by papain solubilizing sucrase-isomaltase complex or by trypsin unable to solubilize it. When microvilous vesicles or trysinized ones were incubated with immunoglobulin G against the sucrase-isomaltase complex or monovalent fragments therefrom, an apparently continuous electron-opaque layer approximately 180 A in width appeared around the external surface of vesicles. Such a layer was not formed on papainized vesicles. Microvillous vesicles and trypsinized ones negatively stained with phosphotungate showed a great number of particles protruding approximately 150 A from the membrane surface, but papainized vesicles did not. The particles existed close to one another and appeared to form a particulate layer 150 A in width on the surface. The antibodies, whether they were divalent or monovalent, increased the width of the layer to approximately 200 A and obscured the fine particulate structure of intact and trypsinized vesicles. Papainized vesicles retained their smooth surface upon interaction with antibodies. These results, together with those with the Triton-solubilized sucrase- isomaltase complex (Nishi and Takesue, 1978), J. Ultra-struct. Res., 62:1- 12), indicate not only that sucrase-isomaltase complexes are located close to one another on the membrane, but also that they or at least their protein portions protrude approximately 150 A from the surface of the trilaminar membrane.
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PMID:Localization of intestinal sucrase-isomaltase complex on the microvillous membrane by electron microscopy using nonlabeled antibodies. 72 98

The T1 variety of tyrosinase is present in both particulate and soluble or readily solubilized forms in the pigmented hypodermis (hair bulbs) of C57BL mice and Harding-Passey mouse melanoma. Trypsin treatment of 35,000g supernatants containing the microsomal (small granule) fraction of gentle homogenates of hair bulbs and melanoma results in significantly increased T1 activity within polyacrylamide gels. Similar treatment of 100,000g supernatants results in a slight increase in T1 activity. Addition of Triton-X or DOC to 35,000g supernatants of hair bulb and melanoma homogenates followed by centrifugation at 100,000g results in a marked enhancement of T1 when the latter supernatants are treated with trypsin. In the absence of trypsin treatment, T1 activity is comparable to nondetergent-treated controls. A slow-moving dopa-reactive band (Ts) is found in electropherograms of the nontrypsinized 100,000g supernants of detergent-treated 35,000g supernatants. It is absent in those treated with trypsin. The slow-moving enzyme appears to give rise to T1 molecules when eluted from acrylamide gels and even to a greater extent when elution is combined with trypsin treatment prior to reelectrophoresis. In mammals, tyrosinase apparently is not derived by a proteolytic activation of protyrosinase.
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PMID:Action of trypsin and detergents on tyrosinase of normal and malignant melanocytes. 81 38


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