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)

Classical techniques for studying modulations of microvascular permeability have a time resolution of minutes. A newly developed method allows continuous measurement of the electrical resistance of the microvascular membrane in vivo (Olesen & Crone 1983). The technique exploits microelectrodes impaled into the vascular lumen and is based on cable analysis of the vessel. It was applied to venules on the surface of the frog brain to test the effect on microvascular permeability of a wide variety of substances. The following agents increased ionic permeability reversibly within seconds: 5-hydroxytryptamine, bradykinin, ATP, ADP, AMP, phospholipase A2, arachidonic acid, leukotriene C4, oxygen-derived free radicals, ionophore A23187, and unbound Evans blue dye. An irreversible permeability increase was induced by protamine sulphate, neuraminidase, trypsin, melittin, and snake venoms from Crotalus durissus terrificus and Bothrops atrox. The following substances were without effect within an administration period of 5 min: histamine, epinephrine, putrescine, angiotensin II, vasoactive intestinal polypeptide (VIP), substance P, neurotensin, vasopressin, adenosine, PGE2, PGF2 alpha, prostacyclin (PGI2), leukotriene B4, albumin, heparin, plant cytokinins, hyaluronidase, thrombin, wasp venom. Variations in pH between 5.1 and 8.6 did not change permeability. Three conclusions are drawn from the observations: (1) the permeability of cerebral microvessels can be modulated by specific agents, (2) the agents induced changes in the endothelium within a few seconds, and (3) the rapid permeability increase induced by inflammatory mediators was less than two-fold and reversible within minutes.
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PMID:Substances that rapidly augment ionic conductance of endothelium in cerebral venules. 348 16

Four uterine-contractile substances (a, b, c and d) were extracted from procedures with acetic acid, n-butanol, distilled water, and methanol from the reaction mixture obtained by incubating rat plasma kininogen with the kininforming enzyme in the rat stomach. Gradient and equilibrium chromatography on SP-Sephadex C-25 columns were carried out with the extract containing these materials (a, b, c and d). The materials could not be separated by chromatography on SP-Sephadex C-25, but were separated by high performance liquid chromatography (HPLC) with a Zorbax ODS reversed-phase column. All the materials (a, b, c and d) contracted the rat uterus and relaxed the rat duodenum. The uterine-contractile activity of the materials was abolished by chymotrypsin, but not by trypsin treatment. The retention times of materials a, c and d on HPLC were different from that of kallidin, MLBK, bradykinin (BK) and neurotensin; but the retention time of material b was equal to that of BK. The content ratio of a: b: c: d was 4: 4: 67: 25, calculated from the uterine-contractile activity of these materials. The apparent molecular weight of the major material c, estimated by gel chromatography, was 1650. Material c contracted the rat uterus (1.2 x 10(-10) g/ml), relaxed the rat duodenum (2 x 10(-10) g/ml), and produced a fall in rabbit blood pressure (4.4 x 10(-8) g/kg). Material c was classified as a biologically BK-like peptide which is distinct from kallidin, MLBK, BK and neurotensin.
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PMID:Kinin formation by catheptic enzyme in rat stomach. 716 63

Neurotensin and neuromedin N are two biologically active related peptides which are encoded in the same precursor molecule. In the rat, the precursor consists of a 169-residue polypeptide containing in its C-terminal region one copy each of neurotensin and neuromedin N. Four Lys-Arg sequences which are thought to represent putative processing sites occur in the precursor molecule. Of these sites, the three that are closest to the C-terminus flank and separate neurotensin and neuromedin N. The fourth precedes a neuromedin N-like sequence. The present studies were aimed at determining the extent to which each of these four dibasic sites is cleaved and at identifying and quantifying the intermediate and mature products to which this cleavage gives rise in extracts from whole rat brain, hippocampus and globus pallidus. This was achieved by means of radioimmunoassays specific for sequences of the neurotensin/neuromedin N precursor that are adjacent to the dibasic processing sites used in combination with high pressure liquid chromatography and arginine-directed trypsin digestion of tissue extracts. In all tissue extracts, it was found that the three most C-terminal dibasic processing sites in the neurotensin/neuromedin N precursor are processed to a similar extent, whereas the dibasic site that precedes the neuromedin N-like sequence is processed to a lesser extent. As reported previously, the globus pallidus was shown to contain proportionally lower levels of neuromedin N than other brain regions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Post-translational processing of the neurotensin/neuromedin N precursor in the central nervous system of the rat--I. Biochemical characterization of maturation products. 805 9

Initial studies on the specificity of the multicatalytic proteinase complex (MPC; EC 3.4.99.46) led to the identification of three distinct proteolytic components designated as trypsin-like, chymotrypsin-like, and peptidylglutamyl-peptide hydrolyzing, all sensitive to inactivation by 3,4-dichloroisocoumarin (DCI), a general serine proteinase inhibitor. The three components cleave the peptidyl-arylamide bonds in the model synthetic substrates, Z-(D)-Ala-Leu-Arg-2-naphthylamide, Z-Gly-Gly-Leu-p-nitroanilide, and Z-Leu-Leu-Glu-2-naphthylamide, respectively. We report here evidence for the presence in the MPC of two additional distinct components, neither of them capable of cleaving the three model substrates. One of these components cleaves the Leu-Gly and the Leu-Ala bonds in the substrates Cbz-Gly-Pro-Ala-Leu-Gly-p-aminobenzoate and Cbz-Gly-Pro-Ala-Leu-Ala-p-aminobenzoate, respectively, and is activated by treatment of the MPC with DCI, N-ethylmaleimide, Mg2+, Ca2+, and low concentrations of sodium dodecyl sulfate and fatty acids. This component is apparently identical with the previously identified DCI-resistant component of the MPC that cleaves preferentially bonds on the carboxyl side of branched chain amino acids in natural peptides including neurotensin and proinsulin [Cardozo, C., Vinitsky, A., Hidalgo, M. C., Michaud, C., & Orlowski, M. (1992) Biochemistry 31, 7373-7380]. It is probably also identical with the component proposed to be the main factor responsible for the caseinolytic activity [Pereira, M. E., Nguyen, T., Wagner, B. J., Margolis, J. W., Yu, B., & Wilk, S. (1992a) J. Biol. Chem. 267, 7949-7955]. The designation "branched chain amino acid preferring" (BrAAP) is proposed for this component. The second component cleaves peptide bonds between the small neutral amino acids Ala-Gly and Gly-Gly in the substrates Cbz-Gly-Pro-Ala-Ala-Gly-p-aminobenzoate and Cbz-Gly-Pro-Ala-Gly-Gly-p-aminobenzoate, respectively. This component is sensitive to inactivation by DCI, N-ethylmaleimide, and organic mercurials, but unlike the BrAAP it is significantly activated neither by Mg2+ or Ca2+ nor by fatty acids or sodium dodecyl sulfate. The designation "small neutral amino acid preferring" (SNAAP) is proposed for this component. Both components are sensitive to inhibition by the peptidyl-aldehydes N-acetyl-Leu-Leu-norleucinal (Ac-LLnL-CHO; calpain inhibitor I) and N-acetyl-Leu-Leu-methioninal (Ac-LLM-CHO; calpain inhibitor II) but are resistant to inhibition by Z-LLF-CHO, a potent inhibitor of the chymotrypsin-like activity.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Evidence for the presence of five distinct proteolytic components in the pituitary multicatalytic proteinase complex. Properties of two components cleaving bonds on the carboxyl side of branched chain and small neutral amino acids. 843 36

Neurotensin (NT) and neuromedin N (NN) are two related biologically active peptides that are encoded in the same precursor molecule. In the rat, the precursor consists of a 169-residue polypeptide starting with an N-terminal signal peptide and containing in its C-terminal region one copy each of NT and NN. NN precedes NT and is separated from it by a Lys-Arg sequence. Two other Lys-Arg sequences flank the N-terminus of NN and the C-terminus of NT. A fourth Lys-Arg sequence occurs near the middle of the precursor and is followed by an NN-like sequence. Finally, an Arg-Arg pair is present within the NT moiety. The four Lys-Arg doublets represent putative processing sites in the precursor molecule. The present study was designed to investigate the post-translational processing of the NT/NN precursor in the rat medullary thyroid carcinoma (rMTC) 6-23 cell line, which synthesizes large amounts of NT upon dexamethasone treatment. Five region-specific antisera recognizing the free N- or C-termini of sequences adjacent to the basic doublets were produced, characterized and used for immunoblotting and radioimmunoassay studies in combination with gel filtration, reverse-phase h.p.l.c. and trypsin digestion of rMTC 6-23 cell extracts. Because two of the antigenic sequences, i.e. NN and the NN-like sequence, start with a lysine residue that is essential for recognition by their respective antisera, a micromethod by which trypsin specifically cleaves at arginine residues was developed. The results show that dexamethasone-treated rMTC 6-23 cells produced comparable amounts of NT, NN and a peptide corresponding to a large N-terminal precursor fragment lacking the NN and NT moieties. This large fragment was purified. N-Terminal sequencing revealed that it started at residue Ser23 of the prepro-NT/NN sequence, and thus established the Cys22-Ser23 bond as the cleavage site of the signal peptide. Two other large N-terminal fragments bearing respectively the NN and NT sequences at their C-termini were present in lower amounts. The NN-like sequence was internal to all the large fragments. There was no evidence for the presence of peptides with the NN-like sequence at their N-termini. This shows that, in rMTC 6-23 cells, the precursor is readily processed at the three Lys-Arg doublets that flank and separate the NT and NN sequences. In contrast, the Lys-Arg doublet that precedes the NN-like sequence is not processed in this system.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Immunological and biochemical characterization of processing products from the neurotensin/neuromedin N precursor in the rat medullary thyroid carcinoma 6-23 cell line. 847 Oct 39

The aim of the study was to investigate whether cholecystokinin, neurotensin, and cholinergic mechanisms act as mediators of bile salt-stimulated exocrine pancreatic secretion. Ten fasting healthy subjects provided with a double-lumen tube received 2, 4, and 6 g cattle bile and 200, 400, and 600 mg Na-taurodeoxycholate (TDC) into the duodenum at 65-min intervals, respectively. The application of TDC was repeated in another 10 subjects after intravenous bolus injection of 2.5 micrograms/kg b.w. atropine followed by continuous infusion of 5 micrograms/kg.h. Secretions of volume, bicarbonate, trypsin, and lipase were determined in 10-min fractions of duodenal juice. Plasma samples were analysed for cholecystokinin-like immunoreactivity (CCK-LI) and neurotensin with radioimmunoassays. Volume, bicarbonate, trypsin, and lipase secretion rates were significantly increased by 4 g and 6 g bile and by all doses of TDC. Incremental volume and bicarbonate output was dose-dependently enhanced by bile and TDC, and trypsin and lipase output by bile. Atropine significantly decreased the baseline values and all responses to TDC. Plasma concentrations and integrated CCK-LI and neurotensin significantly increased after 4 and 6 g bile and after 400 and 600 mg TDC. Atropine did not significantly influence peptide release. It is concluded that both hydrokinetic and ecbolic pancreatic secretion stimulated by intraduodenal bile and TDC are dependent on a cholinergic tone. CCK and probably also neurotensin act as further mediators of the ecbolic effect.
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PMID:Mediators of exocrine pancreatic secretion induced by intraduodenal application of bile and taurodeoxycholate in man. 904 90

The effects of neurotensin on pancreatic exocrine secretion were examined in fasted, conscious White Leghorn hens. A cannula was surgically implanted in the central duct serving the ventral lobe of the pancreas in order to collect pure pancreatic juice. Following recovery, neurotensin was infused intravenously at 3.6 or 10.8 pmol/kg*min. The volume and pH of the pancreatic secretions were recorded and total pancreatic protein concentration, amylase, lipase, trypsin, and chymotrypsin activity were measured every 30 min for 2 hr and compared to secretions following the infusion of 0.9% saline. Our results demonstrated that neurotensin did not affect the pH nor the pancreatic juice protein concentration, but did increase secretion rate following neurotensin infusion at 3.6 pmol/kg*min. Amylase activity was significantly depressed during neurotensin infusions, while lipase (both pancreatic and carboxylester lipase) activity was significantly elevated. The ratio of amylase to lipase activity was especially depressed by neurotensin infusion at 10.8 pmol/kg*min. Insufficient secretory activity prevented a balanced statistical analysis of chymotrypsin activity, but from a pooled analysis, neurotensin had no effect on protease activity in the pancreatic juice. These results support our current research indicating that neurotensin may be a hormonal regulator of postprandial lipid digestion in chickens.
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PMID:Neurotensin modulates the composition of pancreatic exocrine secretions in chickens. 1006 40

The neuropeptide neurotensin (NT) interacts with two types of human receptors (hNTR) termed hNTR-1 and hNTR-2. This study describes a monoclonal antibody (MAb) specific for hNTR-1, B-N6. This MAb binds specifically to hNTR-1, but not to hNTR-2 transfected CHO cells. B-N6 and NT display a reciprocal competition and react in a similar way to trypsin, suggesting that the B-N6 epitope is at or close to the NT binding site on the third extracellular loop. Unlike B-N6, NT induces hNTR-1 internalization. Although neither NT-FITC nor B-N6 binding was detected by flow cytometry on different human cells, specific mRNA expression for hNTR-1 was detected in these cells. In CHO cells expressing hNTR-1 and a luciferase gene coupled to the krox24 reporter, B-N6 and the antagonist SR 48692 inhibited NT-induced intracellular activation of krox24 in a dose-dependent manner. From these results it is concluded that B-N6 is an antagonistic anti-hNTR-1 MAb.
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PMID:An antagonistic monoclonal antibody (B-N6) specific for the human neurotensin receptor-1. 1018 59

The contribution of gastrin-releasing peptide (GRP) in the physiologic pancreatic response to a meal is unknown. We therefore investigated whether immunoneutralization of GRP could influence the exocrine pancreatic response to a meal as well as plasma concentrations of the peptide hormones neurotensin (NT) and cholecystokinin (CCK). Modified Herrera fistulas were implanted in five mongrel dogs. After a standard meal, we analyzed plasma NT, CCK, and GRP, and protein and enzyme (amylase, lipase, trypsin) content of exocrine pancreatic juice. An unspecific rabbit immunoglobulin solution was administered intravenously as a control. This experiment was repeated with a specific anti-GRP-immunoglobulin. The i.v. administration of the anti-GRP-antibody significantly inhibited meal-stimulated pancreatic secretion. Integrated protein output decreased from 58.4 to 36.8 g/180 min (p < 0.05), as did amylase (2,102 to 1,145 KU/180 min; p < 0.05), lipase (2,258 to 1,172 KU/180 min; p < 0.05), and trypsin (5,321 to 4,990 U/180 min). Postprandially released NT decreased from 8,271 to 5,825 pmol/180 min (p < 0.05). In contrast, integrated amounts of CCK remained relatively stable with 473 to 611 pmol/180 min. The neuropeptide GRP is one of the biologically important regulatory factors influencing meal-stimulated pancreatic secretion, as well as the postprandial plasma level of the peptide hormone NT in the dog. These mentioned effects of postprandially released GRP seem not to be mediated by CCK in an endocrine manner.
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PMID:On the role of gastrin-releasing peptide in meal-stimulated exocrine pancreatic secretion. 1043 58

The present study reports, for the first time, that the recombinant hsp65 from Mycobacterium leprae (chaperonin 2) displays a proteolytic activity toward oligopeptides. The M. leprae hsp65 proteolytic activity revealed a trypsin-like specificity toward quenched fluorescence peptides derived from dynorphins. When other peptide substrates were used (beta-endorphin, neurotensin, and angiotensin I), the predominant peptide bond cleavages also involved basic amino acids in P(1), although, to a minor extent, the hydrolysis involving hydrophobic and neutral amino acids (G and F) was also observed. The amino acid sequence alignment of the M. leprae hsp65 with Escherichia coli HslVU protease suggested two putative threonine catalytic groups, one in the N-domain (T(136), K(168), and Y(264)) and the other in the C-domain (T(375), K(409), and S(502)). Mutagenesis studies showed that the replacement of K(409) by A caused a complete loss of the proteolytic activity, whereas the mutation of K(168) to A resulted in a 25% loss. These results strongly suggest that the amino acid residues T(375), K(409), and S(502) at the C-domain form the catalytic group that carries out the main proteolytic activity of the M. leprae hsp65. The possible pathophysiological implications of the proteolytic activity of the M. leprae hsp65 are now under investigation in our laboratory.
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PMID:The Mycobacterium leprae hsp65 displays proteolytic activity. Mutagenesis studies indicate that the M. leprae hsp65 proteolytic activity is catalytically related to the HslVU protease. 1204 73


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