Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Zinc is known to be greatly involved in the regulation of immune functions. Pharmacological zinc supplementation, leading to serum zinc concentrations of more than 0.025 mM, has often been suggested to improve immune responses. However, the exact influence of elevated zinc level on immune functions has not yet been investigated. We found that zinc level selectively enhances cytokine induction by lipopolysaccharide (LPS) in a concentration-dependent fashion: as little as 0.0125 mM supplemental zinc led to nearly 50% elevated interleukin-1 beta (IL-1 beta) levels both in polymorphonuclear cells (PBMC) and whole-blood cultures. The secretion of interferon-gamma (IFN-gamma) could be increased more than 10-fold by 0.1 mM zinc. This could not be observed during stimulation with phytohaemagglutin (PHA). In contrast, zinc levels concentration-dependently down-regulated monocyte activation caused by the superantigens, staphylococcal enterotoxins A and E (SEA, SEE, more than 90% down-regulation by 0.1 mM zinc), the Mycoplasma arthritidis-derived superantigen (MAS), but not toxic shock syndrome toxin-1 (TSST-1), while T-cell response remained unaffected. This was not the result of chemical degradation of the superantigens. We assume that zinc concentration regulates interactions between SEA, SEE and MAS, but not TSST-1 and their major histocompatibility complex (MHC) class II-binding sites. Our data demonstrate that zinc levels control the secretion of IFN-gamma and monokines after both LPS and superantigen challenge within a clinically relevant range of concentrations. This reveals new perspectives and indications for zinc supplementation and also indicates potential risks of therapeutic application of zinc.
 ...
PMID:Zinc regulates cytokine induction by superantigens and lipopolysaccharide. 775 Oct 4

To investigate the effects of metal ion binding to the alpha-PDGFR kinase insert domain, a PCR product representing amino acid residues 691-795 (104 amino acids) was bacterially expressed and purified. Secondary structure prediction and circular dichroism spectroscopy indicated this domain to be a mixed alpha + beta protein with a large coil/turn contribution. This 16 kDa, soluble, nonphosphorylated domain bound to 45Ca2+ and 65Zn2+ through a common shared site. Of the unlabeled divalent and trivalent metal ions tested, Ho3+ = Zn2+ > Ni2+ > Ca2+ = Mn2+ > Mg2+, Ba2+ in competing for 45Ca2+ binding to this domain. In the presence of Ca2+ ions, the conformation of the KI domain changed significantly, and this changed conformation was resistant to subtilisin proteolysis. However, in the presence of Zn2+ ions, the conformation of the KI domain changed only slightly. Nevertheless, Zn2+ ions were more effective in rendering the KI domain resistant to proteolysis as compared to that shown by Ca2+ ions. In vitro binding studies using purified baculovirus-expressed alpha-PDGFR showed a marked increase in binding the p85 N-SH2 domain in the presence of Ca2+ or Zn2+ ions (KD = 0.5 microM), suggesting that metal ion binding enhances association of the p85 N-SH2 domain with the receptor. To confirm this, association of the alpha-PDGFR with the p85 N-SH2 domain was tested in the presence of the KI domain. The nonphosphorylated KI domain was effective in competing with the alpha-PDGFR for the binding of the p85 N-SH2 domain. This effect was more pronounced in the presence of Ca2+ ions. Microinjection of this domain into Xenopus oocytes delayed maturation in the presence of insulin but not progesterone. This suggests that the KI domain has a correctly folded three-dimensional structure compatible with biological activity. Together these findings indicate that the recombinant alpha-PDGFR KI domain binds the p85 N-SH2 domain and this binding is modulated by the presence of a novel divalent metal ion binding site within its structure.
 ...
PMID:A divalent metal ion binding site in the kinase insert domain of the alpha-platelet-derived growth factor receptor regulates its association with SH2 domains. 785 21

Downregulation of functionally relevant surface molecules has been shown to be a powerful regulatory mechanism of Ag surface expression that seems to be of general significance in vivo. CD16-II (Fc gamma RIIIA alpha) is the transmembrane form of the low-affinity receptor for IgG which is expressed on monocytes and NK cells. Occupancy of CD16-II receptor on NK cells induces expression of activation antigens, synthesis of cytokines, and lysis of antibody-coated target cells. Furthermore, after activation the receptor is downregulated from the cell surface. This downregulation could play a physiological role in the NK activation process via CD16 by releasing the antibody-coated target cell and halting signal transduction. The participation of PKC and PTKs in the activation of NK cells via CD16 is clearly established. Thus, we have considered of interest to study the mechanism of CD16-II downregulation in NK cells and the role played by these kinases in the process. The results show that 1,10-phenantroline, a specific inhibitor of Zn(2+)-dependent metalloproteases, inhibits CD16 downregulation induced by CD16 crosslinking, thus suggesting that this process requires the activation of a Zn2+ dependent metalloprotease as it occurs in PMA mediated CD16 downregulation by shedding. Our results also demonstrate that CD16-II downregulation induced by CD16 crosslinking is independent of PKC and PTK activation. In contrast other NK cell activities induced by CD16 crosslinking, such as the induction of activation markers or the production of TNF-alpha, were dependent of PTK activation. The fact that PKC inhibitor staurosporine blocks PMA- but not CD16-induced downregulation suggests that CD16 downregulation can be achieved via two different pathways: one that is PKC dependent and one that is not. The characterization of the Zn(2+)-dependent metalloproteases and the analysis of the regulatory mechanisms involved in its activation will be of interest in order to clarify the physiological relevance of CD16-II release from NK cells as part of the NK activation process.
 ...
PMID:Downregulation of Fc gamma receptor IIIA alpha (CD16-II) on natural killer cells induced by anti-CD16 mAb is independent of protein tyrosine kinases and protein kinase C. 808 66

Neutral endopeptidase (EC 3.4.24.11; NEP) is a membrane-bound zinc-metallopeptidase. The catalytic zinc ion is coordinated to three amino acid residues (His538, His587 and Glu646) and a water molecule. Here, we have systematically substituted potential metal-coordinating amino acid residues (His, Glu, Asp, Cys, Tyr, Ser) for each of the three zinc ligands of NEP using a recombinant polymerase chain reaction procedure. NEP mutants at positions 583 and 587 were devoid of catalytic activity. However, Glu587 NEP and Cys583 NEP were able to bind partially a tritiated inhibitor, the binding of which is dependent on the presence of the zinc atom. At position 646, the aspartate and cysteine mutants exhibited activity. For both mutants Km values were unaltered but kcat values were decreased by about 20-fold. Both mutants bound the tritiated inhibitor with Kd values similar to that of the wild-type enzyme. Our data suggest that neither histidine-583 nor -587 can be replaced by any other ligands. On the other hand, the glutamic acid at position 646 can be converted to an aspartic acid or a cysteine indicating the importance of a negative charge at this position.
 ...
PMID:Substitution of potential metal-coordinating amino acid residues in the zinc-binding site of endopeptidase-24.11. 809 56

Inhibitors of the zinc protease neutral endopeptidase (NEP, EC 3.4.24.11) offer significant therapeutic interest as antihypertensives due to their ability to potentiate the biological action of the circulating natriuretic hormone ANF (atrial natriuretic factor). N-Phosphonomethyl dipeptides bearing a central (4-phenyl)phenylalanine residue have been designed to exert potent and selective NEP inhibition. In particular, (S)-3-[N-[2- [(phosphonomethyl)amino]-3-(4-biphenylyl)propionyl]amino]propionic acid (10a) (CGS 24592) displayed high inhibitory potency in vitro (IC50 = 1.9 +/- 0.1 nM) and a long plasma half-life in rats but lacked oral bioavailability. This drawback was overcome by using esterase-sensitive (acyloxy)alkyl phosphonates. More remarkable, several diaryl phosphonate derivatives of 10a also performed as effective prodrugs. Specifically, the structurally simple diphenyl phosphonate 18 (CGS 25462) induced potent inhibition of NEP ex vivo for at least 8 h after oral administration to rats (30 mg/kg). Its antihypertensive effect was demonstrated in DOCA-salt rats. At 30 mg/kg orally, 18 caused a significant reduction in mean arterial pressure measuring -35 +/- 7 mmHg at 5-h postdosing. The alpha-aminomethyl phosphonate 18 represents a new generation of selective NEP inhibitors that combine high potency, long duration of action, and oral bioavailability. Therefore, it holds promise as a novel therapeutic agent for the treatment of human hypertension and congestive heart failure.
 ...
PMID:N-Phosphonomethyl dipeptides and their phosphonate prodrugs, a new generation of neutral endopeptidase (NEP, EC 3.4.24.11) inhibitors. 812 Aug 68

Heavy metal intoxication of newborn infants fed with "Ba-Pao-Neu-Hwang-San" has been reported every year by many hospitals in Taiwan. About nine years ago, the National Laboratories of Foods and Drugs of the Department of Health, Executive Yuan, received one case report of a five month old female infant who died as a result of long term feeding with "Ba-Pao-Neu-Hwang-San". The drug was found to have contained lead 44,000 ppm. Although this unfortunate incident was propagated by most newspapers, the prescription of this ancient Chinese medicinal preparation is still widely accepted by ordinary people. Herbal medicine doctors prefer complex mineral drugs as did their ancestors thousands of years ago. In the last two years, we have collected 5 samples of "Ba-Pao-Neu-Hwang-San" from different manufacturers and measured the concentration of 16 heavy metals (including Cadmium, Mercury, Arsenic, Lead, Chromium, Manganese, Selenium, Germanium, Nickel, Calcium, Magnesium, Aluminum, Iron, Copper, Zinc, and Vanadium) in these drugs with Inductively-Coupled Plasma Atomic Emission Spectrometry and Graphite Furnace Atomic Absorption Spectrometry. The result of our survey revealed that the first sample (from Tainan) contained mercury 52,800 ppm, the fourth (from Ping-tung) contained mercury 34,500 ppm, and the fifth (from Sin-chu) contained mercury 65,700 ppm. The mercurial contents of these samples were apparently too high to be a safe drug.
 ...
PMID:[Heavy metals in traditional Chinese medicine: ba-pao-neu-hwang-san]. 836 65

Neutral endopeptidase 24.11 (EC 3.4.24.11; NEP) is a membrane-bound Zn-metalloendopeptidase with a catalytic activity and a specificity very similar to that of thermolysin, a bacterial zinc-endoprotease. NEP can be inactivated by reaction with diethylpyrocarbonate, due to the modification of a histidine residue present in the active site of the enzyme. This histidine residue was proposed to be analogous to His231 in thermolysin, which is involved in the stabilization of the tetrahedral intermediate during the transition state. Using site-directed mutagenesis of the cDNA encoding rabbit NEP, we have created two mutants of NEP where His711 was replaced by either Gln or Phe (NEP-Gln711 and NEP-Phe711). Determination of kinetic parameters showed that both mutants had Km values very similar to that of the non-mutated enzyme but that their kcat values were 25-fold lower. The calculated difference in free energy needed to form the transition state complex was increased by 2.2 kcal/mol for both mutants. These observations strongly suggest that His711 is involved in the stabilization of the transition state by forming an hydrogen bond with the oxyanion of the tetrahedral intermediate.
 ...
PMID:Kinetic evidence that His-711 of neutral endopeptidase 24.11 is involved in stabilization of the transition state. 844 Mar 86

The cell-surface zinc metalloproteinase CD10/neutral endopeptidase 24.11 (CD10/NEP) hydrolyzes a variety of peptide substrates and regulates related peptide-mediated cellular responses. Because the enzyme functions as part of a peptide regulatory loop, the fact that CD10/NEP itself varies with cellular activation is of considerable interest. In hematopoietic and nonhematopoietic cell types, the levels of CD10/NEP protein and enzymatic activity correlate with transcript abundance. For these reasons, we investigated the regulation of CD10/NEP transcripts in the phorbol ester-treated acute lymphoblastic leukemia cell line, REH. When REH cells are treated with phorbol myristate acetate (PMA), CD10/NEP transcripts rapidly decrease in a labile protein-dependent manner. PMA has a modest effect on CD10/NEP transcription and significantly reduces CD10/NEP mRNA stability. Of note, the predicted secondary structure of the CD10/NEP 3' untranslated region includes several stem loop structures that may affect the stability of CD10/NEP transcripts.
 ...
PMID:Phorbol ester-mediated regulation of CD10/neutral endopeptidase transcripts in acute lymphoblastic leukemias. 853 91

Dual inhibitors of the two zinc metallopeptidases, neutral endopeptidase (NEP, EC 3.4.24.11) and angiotensin-I converting enzyme, have been the focus of much clinical interest for the treatment of hypertension and congestive heart failure. A novel series of alpha-thio dipeptides containing central cyclic non-natural amino acids were prepared and were evaluated for their ability to inhibit these two metallopeptidases in vitro and in vivo. Most of these compounds were found to be excellent dual inhibitors of ACE and NEP in vitro and several were also found to inhibit angiotensin-I (AI) pressor response in conscious rats when given by intravenous administration. Compound 6n, one of our most potent dual inhibitors in vitro, was found to be more efficacious than captopril in the AI pressor experiment when administered orally to conscious rats. This compound was also found to inhibit plasma NEP activity following oral administration to conscious rats and was more efficacious than acetorphan. The structure-activity relationships and biological activity of these dual inhibitors will be discussed.
 ...
PMID:New alpha-thiol dipeptide dual inhibitors of angiotensin-I converting enzyme and neutral endopeptidase EC 3.4.24.11. 854 78

An interest to the study of superoxide dismutase (SOD) is growing as it has become known that this enzyme may be used as a medical preparation and in the biochemical research. The aim of the work presented is to investigate the influence of temperature and UV radiation on the structural-functional properties of SOD. Copper- and zinc-containing SOD from bovine erythrocytes with the light of a DRT-400 lamp (dose of irradiation 1.5 x 10(3) J/m2) through an UFS-1 light filter (240-390 nm). The influence of temperature (20-85 degrees C) on the functional properties of native and UV modified SOD has been studied. The process of thermodenaturation of the enzyme proceeds at least two consecutive stages. SOD is stable within the temperature interval 20-70 degrees C. Kinetics of thermodenaturation of protein has been studied. It was established that UV light increases enzyme thermostability. Changes found in the kinetic characteristics of the UV-irradiated SOD are apparently due to its conformational rearrangements.
 ...
PMID:[Kinetic regularities of thermal inactivation of superoxide dismutase]. 855 68


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>