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)

Our study of the extended metal environment, particularly of the second shell, focuses in this paper on zinc sites. Key findings include: (i) The second shell of mononuclear zinc centers is generally more polar than hydrophobic and prominently features charged residues engaged in an abundance of hydrogen bonding with histidine ligands. Histidine-acidic or histidine-tyrosine clusters commonly overlap the environment of zinc ions. (ii) Histidine tautomeric metal bonding patterns in ligating zinc ions are mixed. For example, carboxypeptidase A, thermolysin, and sonic hedgehog possess the same ligand group (two histidines, one unibidentate acidic ligand, and a bound water), but their histidine tautomeric geometries markedly differ such that the carboxypeptidase A makes only Ndelta1 contacts, thermolysin makes only Nepsilon2 contacts, and sonic hedgehog uses one of each. Thus the presence of a similar ligand cohort does not necessarily imply the same topology or function at the active site. (iii) Two close histidine ligands HXmH, m </= 5, rarely both coordinate a single metal ion in the Ndelta1 tautomeric conformation, presumably to avoid steric conflicts. Mononuclear zinc sites can be classified into six types depending on the ligand composition and geometry. Implications of the results are discussed in terms of divergent and convergent evolution.
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PMID:Classification of mononuclear zinc metal sites in protein structures. 940 95

In this report, we describe protein damage by a series of metal complexes that mediate the formation of hydroxyl radical. The protein targets used are bovine serum albumin (BSA) and carboxypeptidase A (CPA). BSA contains several electrostatic, hydrogen bonding and hydrophobic binding sites for potential interaction with the metal complexes, and CPA contains a specific phenylalanine binding site. The data presented in this study show that aromatic side chain damage and backbone cleavage occur to similar extents with all the complexes. Reasonable levels of backbone cleavage specificity can be attained with relatively few recognition elements, despite the fact that a diffusible radical mediates cleavage. Incorporation of additional recognition elements can enlarge the set of cleavage sites. We show that the chemical environment of the cleavage reaction, manipulated by using different buffers, can dramatically affect the outcome of the cleavage reaction. Our work suggests that backbone cleavage site is determined by three factors: the binding sites of the metal complexes, the role of reactive sites on the protein backbone, and the influence of the chemical environment on the reaction.
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PMID:Protein cleavage by transition metal complexes bearing amino acid substituents. 984 Sep 67

Native carboxypeptidase A has been crystallized in a new crystal form, and the structure has been refined with X-ray data to 2.0 A resolution. In contrast to the previously published structure [Rees, D. C., Lewis, M., and Lipscomb, W. N. (1983) J. Mol. Biol. 168, 367-387], no active-site amino acids are involved in the crystal packing. The important Tyr248 is stabilized inside the active site by a hydrogen bond and by interactions with Ile247. The proposed role of Tyr248 in the induced fit mechanism is therefore not supported by the findings in this structure of native carboxypeptidase A. The structure has a partly populated inhibitory Zn2+ site in close proximity to the catalytic Zn2+ as evident from X-ray anomalous dispersion data. A hydroxo bridge is found between the catalytic Zn2+ and the inhibitory Zn2+ with a Zn2+-Zn2+ distance of 3.48 A. In addition, the inhibitory Zn2+ has Glu270 as a monodentate ligand. No other protein ligands to the inhibitory Zn2+ are seen. The crystals were grown at 0.3 M LiCl and weak evidence for a binding site for partly competitive inhibitory anions is observed.
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PMID:Native carboxypeptidase A in a new crystal environment reveals a different conformation of the important tyrosine 248. 984 22

The role of the signal transmission pathway of thunberginol A (TA) in mast cell degranulation was examined using rat peritoneal mast cells. First of all, we investigated the cellular distribution of TA using fluorescent microscopy. This indicated that TA is immediately incorporated into cells and distributes in cytosol around the nucleus. We then investigated the effect of TA on mast cell protein tyrosine phosphorylation, which is part of the signal transduction cascade for degranulation. TA non-specifically inhibited the tyrosine phosphorylation induced by compound 48/80 (Co. 48/80), at 10 to 100 microM, and orthovanadate/hydrogen peroxide at more than 50 microM in a dose-dependent manner. As far as the intracellular Ca2+ change in fluo-3-loaded cells was concerned, TA (10 microM) suppressed the rise in Ca2+ induced by antigens, ionomycin and thapsigargin, while TA did not suppress the rise induced by Co. 48/80. This evidence suggests that TA mainly inhibits extracellular Ca2+ influx, but TA does not act on the intracellular Ca2+ mobilization from the endoplasmic reticulum. We also investigated the influence of TA on the cytoskeleton and membrane changes using mast cells and erythrocytes. TA (10 microM) inhibited the cytoskeletal assembly formation in dicyanovinyl julolidin-loaded mast cells induced by Co. 48/80. Moreover, TA suppressed the hypotonic hemolysis of erythrocytes, from 3 to 1000 microM, in a dose-dependent manner. These results suggest that inhibition of protein tyrosine phosphorylation, extracellular Ca2+ influx and cytoskeletal assembly formation, and membrane stabilization are involved in the inhibitory effect of TA in mast cell degranulation.
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PMID:The role of thunberginol A, an isocoumarin constituent of Hydrangeae Dulcis Folium, on the signal transmission pathway for rat mast cell degranulation. 1051 14

In the Brown Norway (BN) rat, chemical compounds [mercuric chloride (HgCl2), D-penicillamine or gold salts] induce a T(h)2-dominated autoimmune syndrome with tissue injury in the form of a vasculitis and arthritis. An early phase of vasculitis in the model occurs within 24 h of an injection of HgCl2, is alphabeta T cell independent and involves the mast cell. In addition, HgCl2 induces IL-4 mRNA in mast cells from BN rats. Our recent work has demonstrated that the balance of oxidative/antioxidative influences plays an important role in the modulation of mast cell function (degranulation) in chemically induced autoimmunity. The aim of this study was to determine, in mast cells, whether oxidative status influences IL-4 transcription and translation, which is required for the development of a T(h)2 response. Exposure of the mast cell line RBL-2H3 to HgCl2 enhanced both IL-4 mRNA and its promoter activity. Oxidative stress by hydrogen peroxide mimicked the effects of HgCl2 in enhancing IL-4 promoter activity. The enhancement of IL-4 gene expression by HgCl2 was significantly reduced by antioxidants (both sulphydryl and non-sulphydryl containing). The same pattern of regulation was also observed on IL-4 protein expression in the mast cells. These data suggest a novel mechanism of IL-4 transcriptional up-regulation by oxidative stress. Our results provide evidence to support our hypothesis that alterations in intracellular reactive oxygen species production modulate both IL-4 gene expression and mast cell function.
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PMID:IL-4 gene expression up-regulated by mercury in rat mast cells: a role of oxidant stress in IL-4 transcription. 1122 98

2-Benzyl-3,4-iminobutanoic acid (3) was evaluated as a novel class of inhibitor for carboxypeptidase A (CPA). All four stereoisomers of 3 are found to have competitive inhibitory activity for CPA, although their inhibitory potencies differ widely with (2R,3R)-3 being most potent. The molecular modeling study for CPA(2R,3R)-3 complex suggested that the lone pair electrons on the nitrogen of the aziridine ring in the inhibitor forms a coordinative bond with the active site zinc ion and the proton on the nitrogen is engaged in hydrogen bonding with one of the carboxylate oxygens of Glu-270.
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PMID:2-Benzyl-3,4-iminobutanoic acid as inhibitor of carboxypeptidase A. 1167 37

We have studied the effect of nitric oxide (NO) and hydrogen peroxide (H(2)O(2)), two reactive oxygen species (ROS) on histamine release (HR) from RBL-2H3 cells, a rat mucosal-type mast cell line. Marked HR was elicited by antigen (DNP-HSA), calcium ionophore A23187, sodium fluoride or phospholipase C, but not with compound 48/80 or 1,2-dioctanoyl-sn-glycerol. The NO-synthase substrate L-arginine and its inactive enantiomer (D-arginine), each on its own, induced a small but significant increase in HR above the basal level. However, the NO-donors (sodium nitroprusside or NaNO(3)) or the NO-synthase inducer lipopolysaccharide did not induce HR. Moreover, methylene blue (MB), which inhibits guanylate cyclase and N(omega)-nitro-L-arginine (L-NA), an inhibitor of NO synthase, were also without effect on either the basal HR or the L-arginine-induced HR. HR induced by A23187, DNP-HSA, sodium fluoride or phospholipase C was markedly reduced by MB, but mildly by L-NA (both at 1-100 microM). H(2)O(2) (0.01-1.0 mM) on its own did not induce HR, but it had a potent inhibitory effect on DNP-HSA- or A23187-induced HR, which was not reversed by L-NA (1-100 microM). Taken together, it seems that neither the stimulatory nor the inhibitory effects of the NO-related compounds on HR can be attributed to NO, but rather to other mechanisms. The inhibition of HR by H(2)O(2) also does not involve NO and suggests a negative feedback regulatory role for the peroxide in the allergic inflammation.
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PMID:Effects of nitric oxide and hydrogen peroxide on histamine release from RBL-2H3 cells. 1172 90

Both D- and L-isomers of N-(hydroxyaminocarbonyl)phenylalanine () were shown to have strong binding affinity towards carboxypeptidase A (CPA) with D- being more potent than its enantiomer by 3-fold (Chung, S. J.; Kim, D. H. Bioorg. Med. Chem. 2001, 9, 185.). In order to understand the reversed stereochemical preference shown in the CPA inhibition, we have solved the crystal structures of CPA complexed with each enantiometer of up to 1.75 A resolution. Inhibitor L- whose stereochemistry belongs to the stereochemical series of substrate binds CPA like substrate does with its carbonyl oxygen coordinating to the active site zinc ion. Its hydroxyl is engaged in hydrogen bonding with the carboxylate of Glu-270. On the other hand, in binding of D- to CPA, its terminal hydroxyl group is involved in interactions with the active site zinc ion and the carboxylate of Glu-270. In both CPA small middle dot complexes, the phenyl ring in is fitted in the substrate recognition pocket at the S(1)' subsite, and the carboxylate of the inhibitors forms bifurcated hydrogen bonds with the guanidinium moiety of Arg-145 and a hydrogen bond with the guanidinium of Arg-127. In the complex of CPA small middle dotD-, the carboxylate of the inhibitor is engaged in hydrogen bonding with the phenolic hydroxyl of the down-positioned Tyr-248. While the L- binding induces a concerted movement of the backbone amino acid residues at the active site, only the downward movement of Tyr-248 was noted when D- binds to CPA.
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PMID:Insight into the stereochemistry in the inhibition of carboxypeptidase A with N-(hydroxyaminocarbonyl)phenylalanine: binding modes of an enantiomeric pair of the inhibitor to carboxypeptidase A. 1193 61

The effects of two mast cell stabilisers, sodium cromoglycate (SCG) and doxantrazole, on the formation of reactive oxygen species (ROS) were studied. Guinea-pig alveolar macrophages (AMs) generated lucigenin-dependent chemiluminescence (LDCL). This was increased when the cells were stimulated by phorbol myristate acetate (PMA) or zymosan (by 133% and 464%, respectively, in total LDCL over 60 min). SCG decreased PMA-induced LDCL at higher concentrations (10 mM, by 55%) than doxantrazole (1 mM, by 75%). SCG decreased radical production by AMs in response to zymosan in a concentration-dependent manner by < or = 72%. Doxantrazole (0.1-1 mM) diminished total LDCL by 30-80%. In addition, glucose oxidase led to LDCL generation when incubated with glucose in a cell-free medium. This was inhibited by 47-83% in the presence of SCG or doxantrazole. SCG and doxantrazole inhibited the hydrogen peroxide- and peroxynitrite-induced LDCL by < or = 92%. Moreover, these drugs slightly increased the survival rate of the AMs. It is concluded that doxantrazole- and sodium cromoglycate-inhibited lucigenin-dependent chemiluminescence production by guinea-pig alveolar macrophages is due to a direct scavenging effect on reactive oxygen species. Doxantrazole is approximately 10-times more potent. Mast cell stabilisers may be effective in allergic asthma not only by preventing the allergen-induced mediator release, but also by preventing radical-induced lung damage.
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PMID:Sodium cromoglycate and doxantrazole are oxygen radical scavengers. 1241 77

Mast cells and macrophages live in close proximity in vivo and reciprocally regulate one another's function in various ways. Although activated macrophages possess a powerful reactive oxygen species (ROS) generating system, there is conflicting evidence regarding whether mast cells can produce ROS. We used the highly sensitive real-time chemiluminescent probe Pholasin to examine ROS release by peritoneal macrophages and mast cells isolated from OVA-sensitized rats. Macrophages stimulated with PMA (0.8 microM) or ionomycin (1 microM), but not OVA (1 microg/ml), released high-level ROS, levels of which peaked after 3-7 min and declined to baseline levels within 1 h. Superoxide was identified as the major ROS species induced by PMA but not by ionomycin. In contrast, purified mast cells stimulated with PMA released low-level ROS, which was entirely due to the contaminating (2%) macrophages, and did not release any detectable ROS in response to ionomycin or OVA at concentrations that induced degranulation. Stimulation of mixed cell populations with PMA to induce macrophage ROS release led to 50% inhibition of serotonin release from mast cells stimulated 5 min later with OVA. The PMA-induced inhibitory factor was identified as hydrogen peroxide. In conclusion, activated rat peritoneal macrophages but not mast cells produce ROS, and macrophage-derived hydrogen peroxide inhibits mast cell degranulation. The latter could be an important mechanism whereby phagocytic cells regulate mast cell activation and promote resolution of IgE-mediated inflammation.
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PMID:A comparison of reactive oxygen species generation by rat peritoneal macrophages and mast cells using the highly sensitive real-time chemiluminescent probe pholasin: inhibition of antigen-induced mast cell degranulation by macrophage-derived hydrogen peroxide. 1242 69


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