Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mouse mast cell protease 7 (mMCP-7) is a tryptase stored in the secretory granules of mast cells. At the granule pH of 5.5, mMCP-7 is fully active and is bound to heparin-containing serglycin proteoglycans. to understand the interaction of mMCP-7 with heparin inside and outside the mast cell, this trytase was first studied by comparative protein modeling. The "pro" form of mMCP-7 was then expressed in insect cells and studied by site-directed mutagenesis. Although mMCP-7 lacks known linear sequences of amino acis that interact with heparin, the three-dimensional model of mMCP-7 revealed an area on the surface of the folded protein away from the substrate-binding site that exhibits a strong positive electrostatic potential at the acidic pH of the granule. In agreement with this calculation, recombinant pro-mMCP-7 bound to a heparin-affinity column at pH 5.5 and readily dissociated from the column at pH > 6.5. Site-directed mutagenesis confirmed the prediction that the conversion of His residues 8,68, and 70 in the positively charged region into Glu prevents the binding of pro-mMCP-7 to heparin. Because the binding requires positively charged His residues, native mMCP-7 is able to dissociate from the protease/proteoglycan macromolecular complex when the complex is exocytosed from bone marrow-derived mast cells into a neutral pH environment. Many hematopoietic effector cells store positively charged proteins in granules that contain serglycin proteoglycans. The heparin/mMCP-7 interaction, which depends on the tertiary structure of the tryptase, may be representative of a general control mechanism by which hematopoietic cells maximize storage of properly folded, enzymatically active proteins in their granules.
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PMID:Packaging of proteases and proteoglycans in the granules of mast cells and other hematopoietic cells. A cluster of histidines on mouse mast cell protease 7 regulates its binding to heparin serglycin proteoglycans. 764 36

In this paper, data are presented on purification and properties of a new serine endopeptidase (duodenase) isolated from bovine duodenum mucosa. The enzyme has been purified to homogeneity by combinations of ammonium sulphate fractionation, carboxymethyl-cellulose 52 chromatography, and affinity chromatography on Sepharose 4B with Kunitz soybean trypsin inhibitor as a ligand. Some physicochemical properties of this protease have been investigated. The molecular mass of the purified duodenase was determined to be 29 +/- 0.5 kDa by SDS/PAGE and G-2000 SW column chromatography. The enzyme molecule is a single chain and the native enzyme is a monomeric protein. Its isoelectric point was estimated to be 10 +/- 0.2. Duodenase has two forms (I and II) which possess similar properties but differ in their amino acid composition. The new protease is a glycoprotein and contains approximately 3.5% sugars. The enzyme displays trypsin-like and chymotrypsin-like activities and hydrolyzes the amide bonds of substrates having Lys, Arg, Tyr, Phe and Leu residues at the P1 position. Duodenase is most active at pH 7.9-8.2. Duodenase was irreversibly inhibited by diisopropylphosphofluoridate and phenylmethanesulphonyl fluoride, indicative of an active-site serine in this protease. alpha-N-Tosyl-L-lysine chloromethane and alpha-N-tosyl-L-phenylalanine chloromethane, which react with an active His, caused marked inhibition of trypsin-like and chymotrypsin-like activities of duodenase. The enzyme activity was strongly suppressed by trypsin inhibitors from different sources (soybeans, bovine lungs and Lima beans). Chicken egg white ovomucoid had no effect on the duodenase activity. The N-terminal sequence of the native duodenase (24 amino acid residues) shows high similarity with those of human and murine cytotoxic T-lymphocyte granzymes, human leukocyte cathepsin G and rat mast cell chymases. The biological role of duodenase is discussed.
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PMID:Duodenase, a new serine protease of unusual specificity from bovine duodenal mucosa. Purification and properties. 786 48

1. Mast cell populations in rat lung and spleen were characterized by the presence of two specific protease markers, rat mast cell protease I and II, using both histochemical and radioimmunoassay techniques. Three mast cell populations with different size, morphology, and localization were found in lung and spleen and were identified according to the expression of rat mast cell protease I (RMCPI+) or rat mast cell protease II (RMCPII+) or of both proteases (RMCPI/II+). 2. All three mast cell types were in the vicinity of calcitonin-gene-related-peptide-immunoreactive (CGRP+) nerve fibres in controls as well as in rats infected by Nippostrongylus brasiliensis in which a large increase in the number of both RMCPII+ and RMCPI/II+ mast cells was found. Ablation of the CGRP+ fibres by neonatal treatment with capsaicin resulted in a marked increase in the number of RMCPII+ and RMCPI/II+ cells in lung and, even more, in spleen of adult rats. 3. The interaction of mast cells with CGRP+ C-fibres was assessed pharmacologically by evaluation of the effects of histamine H3-receptor ligands known to act on various types of nerve endings, including those of C-fibres. The effects of H3-receptor ligands were assessed in controls, nematode-infected rats and neonatally capsaicinized rats. Mast cell activity was evaluated by measurement of [3H]histamine synthesis from [3H]histidine. In control rats, administration of the H3-receptor agonist (R)-alpha-methylhistamine and antagonist thioperamide, decreased and enhanced respectively [3H]histamine synthesis in lung and spleen, indicating a tonic control of mast cell activity by histamine via H3-receptors. Such effects were not found in the jejunum, although RMCPII+ mast cells are in close apposition with neuropeptide-containing fibres. The effects of the H3-receptor agents were maintained in lung and spleen of nematode-infected rats, but were almost suppressed in capsaicinized rats. 4. It is concluded that the control of mast cells by histamine acting at H3-receptors involves neuropeptide-containing nerves and presumably reflects the operation of a local neuron-mast cell feedback loop controlling processes such as 'neurogenic inflammation'. This loop still functions when mast cells proliferate in an inflammatory condition. These observations suggest that the use of histamine H3-receptor agonists may constitute a novel therapeutic approach to limit excessive inflammatory responses resulting from dysregulation of this feedback loop.
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PMID:Functional relationship between mast cells and C-sensitive nerve fibres evidenced by histamine H3-receptor modulation in rat lung and spleen. 792 60

Aspirin therapy for patients with systemic mast cell disease (SMCD) decreases the production of prostaglandin D2, which is thought to be a major mediator of flushing. Paradoxically, in 5 to 10% of patients with SMCD, administration of aspirin causes massive mediator release and an anaphylactoid reaction. We attempted aspirin desensitization in a 34-year-old man with SMCD (confirmed by bone marrow biopsy) who was incapacitated by severe flushing episodes and hypotension. His baseline mediator levels of plasma calcitonin, urinary histamine, and urinary N-methyl-imidazoleacetic acid were abnormal. Pentagastrin stimulation increased the plasma level of calcitonin from 47 pg/mL to 130 pg/mL (normal, less than or equal to 110) at 5 minutes. Oral aspirin desensitization was begun; however, after a cumulative dose of 620 mg, an anaphylactoid reaction ensued in conjunction with hypotension, abdominal cramping, and flushing. Coincidentally, 1 hour after the episode, the plasma calcitonin level increased from 37 pg/mL to 540 pg/mL, and the serum tryptase level increased from 1 ng/mL to 3.9 ng/mL. Six hours after the episode, the urine level of histamine increased from 90 micrograms/g creatinine to 337 micrograms/g creatinine, and the urinary N-methylimidazoleacetic acid increased from 32 mg/24 h to 81 mg/24 h. Hence, the patient had increased basal levels of plasma calcitonin that increased substantially during aspirin desensitization and increased to above the upper limit of normal during pentagastrin stimulation. Human mast cells may be capable of producing calcitonin or causing secretion of calcitonin in response to skeletal changes.
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PMID:Increased plasma calcitonin levels in systemic mast cell disease. 793 97

A peculiar point mutation results in constitutive activation of c-kit receptor tyrosine kinase (KIT) in three different tumor mast cell lines; ie, the HMC-1, P-815, and RBL-2H3. Because constitutive activation of KIT was also observed in the FMA3 mouse mastocytoma cell line, we investigated the molecular mechanism. Sequencing of the whole coding region of the c-kit showed that the point mutation found in HMC-1, P-815, and RBL-2H3 cells was absent in FMA3 cells and that the c-kit cDNA of FMA3 cells carried an in-frame deletion of 21 base pairs (bp) encoding Thr-Gln-Leu-Pro-Tyr-Asp-His at codons 573 to 579 at the juxtamembrane domain. The FMA3-type c-kit cDNA with 21 bp deletion was introduced into the IC-2 cell line, which was derived from murine cultured mast cells. IC-2 cells were dependent on interleukin (IL)-3 and did not express KIT on the surface. In IC-2 cells introduced with the FMA3-type c-kit cDNA, KIT was constitutively phosphorylated on tyrosines and activated. Moreover, the FMA3-type KIT was dimerized without the stimulation by stem cell factor (SCF), a ligand for KIT. The spontaneously dimerized FMA3-type KIT without SCF binding was not internalized even after the activation. IC-2 cells expressing the FMA3-type KIT grew in suspension culture without IL-3 and SCF and became leukemic in nude athymic mice. The deletion of seven amino acids at the juxtamembrane domain appeared to be a new activating mutation of KIT that might be involved in neoplastic growth of mast cells.
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PMID:Constitutive activation of c-kit in FMA3 murine mastocytoma cells caused by deletion of seven amino acids at the juxtamembrane domain. 854 52

Perturbed angular correlation of gamma-rays (PAC) spectroscopy has been used to investigate the angiotensin-I-converting enzyme (ACE) of rabbit lung. By substituting the zinc ions in ACE with excited 111mCd2+ ions, analysis of PAC spectra gave directly the percentage of cadmium ions bound to ACE. The result of the analysis was a dissociation constant of about 1 microM for the cadmium-ACE complex, and a stoichiometry of two moles cadmium/mole enzyme. Cadmium binding is thus about two orders of magnitude weaker than zinc binding to ACE but two orders of magnitude stronger than cobalt binding. PAC spectra monitor the nuclear quadrupole interaction (NQI) for 111mCd. The NQI for ACE exhibits very low frequencies in the PAC spectra with a rather large spectral broadening. In the presence of the inhibitor ramiprilat, the frequencies increase but the spectral broadening is about the same as for ACE without inhibitor. When the inhibitor captopril is added, very high frequencies are obtained consistent with sulfur binding, but now with a narrower distribution of NQI's. A simple molecular orbital analysis of the obtained NQI's has been performed, using a coordination sphere of two His, one Glu residue and a solvent ligand, equivalent to the zinc ligands in thermolysin and carboxypeptidase. The calculated spectral parameters could be modelled with the measured parameters if the solvent ligand is H2O in free ACE, carboxylate from ramiprilat in the ACE-ramiprilat complex and a mercapto group in the ACE-captopril complex. The coordination geometry for cadmium carboxypeptidase obtained by X-ray diffraction gives a calculated set of NQI parameters consistent with the measured parameters for cadmium in the captopril-ACE complex using a mercapto group as the solvent ligand. However, for ACE and its complex with ramiprilat, a significant distortion of the cadmium geometry for carboxypeptidase A had to be adopted in order to calculate NQI's close to the experimental values.
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PMID:Effect of inhibitors on the coordination geometries of cadmium at the metal sites in angiotensin-I-converting enzyme. 857 35

The practical application of exopeptidase has been limited by the high cost of the enzymes resulting from the low content of individual exopeptidase in the raw material. This can be overcome by the use of a combination of all the exopeptidases in the same enzyme source, as well as the use of the enzyme immobilization technology. A porcine pancreatic exopeptidase mixture was prepared by the ammonium sulfate precipitation at 35% saturation of the autolyzed pancreatic juice. The enzyme preparation was immobilized on thin shrimp chitin film by crosslinking with glutaraldehyde. The immobilized porcine pancreatic exopeptidases (IPPE) was effective in releasing the free amino acids from peptides. Of these amino acids, the concentrations of arginine, lysine, histidine, tyrosine, phenylalanine, leucine, and glutamine were increased much more than those of other amino acids. This indicated that both the porcine pancreatic exopeptidases preparation and the IPPE contained carboxypeptidase A, B, and aminopeptidase. The IPPE was also efficient in the decrease of the hydrophobicity of protein hydrolysates demonstrated by hydrophobic chromatographic analysis. This led to the application of the immobilized exopeptidases in protein hydrolysate debittering. The IPPE was able to remove the bitterness of the tryptic/chymotryptic casein hydrolysates.
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PMID:The immobilized porcine pancreatic exopeptidases and its application in casein hydrolysates debittering. 867 84

Carnosine and anserine are present in high concentrations in most skeletal muscles. In addition, carnosine and homocarnosine have been detected in brain and cardiac muscle. Other tissues have been found to be devoid of these histidine-containing dipeptides. However, Flancbaum et al. reported that carnosine was present in every rodent and human tissue analyzed. These authors postulated that carnosine serves as a non-mast cell reservoir for histidine which becomes available for histamine synthesis during periods of physiological stress. We have analyzed many rat and human tissues using an immunohistochemical procedure. Carnosine and related dipeptides were detected in skeletal muscle, cardiac muscle and brain, but not in kidney, liver, lung or several other organs. These negative results seem valid since the immunoassay gave positive staining in the tissues generally known to contain carnosine.
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PMID:The distribution of carnosine and related dipeptides in rat and human tissues. 868 92

The chick pineal gland contains histamine and tele-methylhistamine. The levels of both substances are elevated after treatment of chicks with the amino acid precursor of histamine, L-histidine (1 g/kg, ip). In control and L-histidine-loaded animals the pineal levels of histamine and tele-methylhistamine are higher in light-exposed than in dark-adapted animals (measured at the end of the light phase and in the middle of the dark phase of 12 hr light, 12 hr dark illumination cycle, respectively). The chick pineal gland contains histamine-immunofluorescent cells displaying mast cell morphology; they are seen in the vicinity of the capsule and in the parenchyma. Enzymatic studies showed the presence of the activity of histamine synthesizing and inactivating enzyme, i.e., L-histidine decarboxylase (HDC) and histamine-methyltransferase (HMT). The detected enzyme activities were sensitive to specific inhibitors of HDC (alpha-fluoromethylhistidine and alpha-hydrazinohistidine) and HMT (quinacrine and metoprine); inhibitors of aromatic amino acid decarboxylase alpha-methyl-DOPA and NSD-1015 were inactive on HDC. Exogenous histamine added to organ-cultured chick pineals strongly stimulated endogenous cyclic AMP accumulation and moderately increased melatonin secretion. The data, considered collectively, suggest that in avians histamine, probably originating from the pineal mast cell compartment, may function as a regulator of pineal gland activity.
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PMID:Histamine in the chick pineal gland: origin, metabolism, and effects on the pineal function. 906 67

In this study, we have characterized the phenotype of mast cells in rat dura mater and their topological and functional relationships with C-fibers in normal and inflammatory conditions. Three mast cell populations with different size, morphology and localization were characterized by their content of specific neutral serine proteases. They showed immunoreactivity corresponding to rat mast cell protease I, rat mast cell protease II, or both proteases. Using confocal microscopy, all three mast cell types were observed in close apposition (distance less than 100 nm) to calcitonin gene-related peptide- and substance P-immunoreactive nerve fibers in both controls and rats infected with the nematode Nippostrongylus brasiliensis. After nematode infection or neonatal treatment with capsaicin, a large increase in the number of rat mast cell protease II-immunoreactive mast cells was found within dura mater segments (+1478% and +596%, respectively), without concomitant changes of rat mast cell protease I- or rat mast cell protease I/II-immunoreactive mast cells. Under both these conditions, the increase in mast cell number was accompanied by a significant increase in rat mast cell protease II level within tissue extracts (+281% after nematode infection and +36% after capsaicin treatment). The functional interaction of mast cells with sensory nerve fibers in the dura mater was assessed by evaluating [3H]histamine synthesis after administration of L-[3H]histidine, an index of mast cell activity. The H3 receptor agonist (R)-alpha-methylhistamine (15 mg/kg, i.p.) had no effect, but administration of the H3 receptor antagonist, thioperamide (10 mg/kg, i.p.), resulted in a significant increase of [3H]histamine synthesis (+62%). This effect was reduced in neonatal capsaicin-treated rats, but not completely suppressed (+35%), very likely because of partial denervation, as assessed by monitoring calcitonin gene-related peptide immunoreactivity. It is concluded that, in the dura mater, as in peripheral tissues, sensory nerve fibers and mast cells actively synthesizing and releasing histamine form a short inhibitory feedback loop involving prejunctional H3 receptors that could regulate the release of pro-inflammatory mediators, thus limiting the extent of inflammatory reactions.
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PMID:Functional relationships between sensory nerve fibers and mast cells of dura mater in normal and inflammatory conditions. 907 Jul 55


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