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

The activation or interruption of the responses induced by regulatory peptides are ensured by ectoenzymes, the most important of them belonging to the group of zinc metallopeptidases. Thus angiotensin converting enzyme (ACE) forms the hypertensive peptide angiotensin II from its inactive precursor AI. This also the case for aminopeptidase N (APN) and neutral endopeptidase 24.11 (NEP, CALLA) which together inactivate the endogenous opioid peptides, enkephalins, whereas only NEP is involved in the metabolism of the atrial natriuretic factor (ANP) at the kidney and vascular levels. The pharmacological effects resulting from the inhibition of these enzymatic processes will appear only in tissues where the peptide substrate is tonically or phasically released. This promising approach is expected to avoid, or at least to minimize, the side effects resulting from excessive and ubiquitous stimulation of peptide receptors by exogenously administered agonists or antagonists. The essential amino acids known to be present in the active site of the bacterial endopeptidase thermolysin from crystallographic studies, have also been found in NEP by using a new program of sequence comparison associated with mutagenesis experiments. Several classes of selective inhibitors of NEP, APN and ACE have been rationally designed by taking into account the structural differences in the active site of these peptidases. Thus, the retro-inversion of the amide bond of the NEP inhibitor thiorphan resulted in the elimination of a residual interaction with ACE. Moreover, we have proposed to associate inhibitory potencies towards two peptidases in the same compound. Thus kelatorphan HONH-CO-CH2-CH(CH2 phi)-CONH-CH(CH3)-COOH and other systemically-active mixed NEP/APN inhibitors were shown capable of completely blocking enkephalin metabolism in vivo. This concept has been extended to mixed NEP/ACE inhibitors with compounds such as HS-CH2-CH(CH2 phi)-CONH-CH(CH2R)-COOH where R = CH-(CH3)2 (ES 34) or -OCH2 phi (ES 37). Only mixed inhibitors of NEP and APN are able to produce potent analgesia after intracerebroventricular or systemic administration without the major side effects of morphine (tolerance and dependence). Thiorphan or its prodrugs acetorphan or sinorphan lead to a increase in natriuresis and diuresis by protection of ANP degradation, but without any significant antihypertensive effect. Contrastingly mixed NEP/ACE inhibitors such as ES34 induce decreases in blood pressure higher than those that produced by the association of selective NEP and ACE inhibitors.
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PMID:[New approach in the research of analgesics and antihypertensive agents]. 184 70

We have investigated the possible presence of endothelin-metabolizing neutral endopeptidase (NEP, EC 3.4.24.11) on A10 cell membranes using [125I]-ET-1 binding and direct measurements of NEP. NEP activity of A10 cell membranes has been compared to that of solubilized rat kidney brush border membranes (KNEP). Specific [125I]-ET-1 (50 pM) binding (defined with 100 nM ET-1) to A10 cell membranes was increased in a concentration dependent manner by the selective NEP inhibitors thiorphan, phosphoramidon, and SQ 28,603 [(+/-)-N-[2-(mercaptomethyl)-1-oxo-3-phenylpropyl]-beta-alanine] with EC50 values of 9.4, 28.4, and 5.7 nM respectively. At equilibrium (150 min), 70% more specific binding was apparent in the presence of these inhibitors. Phosphoramidon (2 microM) did not alter Bmax values, but it decreased the apparent KD for [125I] ET-1 from 63 (+/- 3) to 27 (+/- 2) pM. Thiorphan, phosphoramidon, and SQ 28,603 inhibited A10 cell NEP activity with IC50 values of 5.3, 36.5, and 6.0 nM respectively, which was similar to values obtained with KNEP (3.6, 22.6, and 3.5 nM). ET-1 inhibited A10 cell NEP, and KNEP with IC50 values of 30 and 21.3 microM respectively. The order of inhibitory potencies: ET-3 greater than ET-1 = ET-2 greater than or equal to sarafotoxin-6b was similar for both systems. These data suggest A10 cell membranes contain a NEP which has similar characteristics to NEP 24.11, and which actively metabolizes [125I]-ET-1.
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PMID:Vascular A10 cell membranes contain an endothelin metabolizing neutral endopeptidase. 201 30

The effect of peptidase inhibitors on neuropeptide release from peripheral endings of capsaicin-sensitive sensory neurons was studied in cerebral superior sagittal and transverse sinuses of guinea-pig. Capsaicin (1 microM)-evoked release of substance P-like immunoreactivity (SP-LI) was increased in a concentration-dependent manner by thiorphan (0.1-10 microM). Captopril (10 microM) or a mixture of bestatin (10 microM), leupeptin (10 microM) and bacitracin (10 microM) did not affect the capsaicin-evoked SP-LI release. Thiorphan (10 microM) increased also the capsaicin-evoked release of neurokinin A-like immunoreactivity (TK-LI) and calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) by 228% and 172%, respectively, while captopril (10 microM) was without effect. Thiorphan (10 microM), but not captopril (10 microM), enhanced by 239% CGRP-LI release induced by bradykinin (10 microM). In the cerebral venous vessels neutral endopeptidase (EC 3.4.24.11, NEP)-like activity was 58.8 +/- 6.1 pmol/mg protein/min, while angiotensin converting enzyme-like activity was below the detection limit of the assay. A thiorphan-sensitive mechanism, putatively attributable to NEP, plays a major role in the inactivation of peptides released from or acting on capsaicin-sensitive sensory fibres of cerebral venous sinuses of guinea-pig.
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PMID:The effect of thiorphan on release of sensory neuropeptides from guinea-pig cerebral venous sinuses. 206 52

Nonadrenergic, noncholinergic contractile responses of guinea pig hilar bronchi to transmural electrical stimulation (TES) have been suggested to be due to release of endogenous tachykinins from capsaicin-sensitive neurons (C-fibers). Thiorphan and phosphoramidon, inhibitors of neutral endopeptidase (NEP, the major enzyme responsible for degrading tachykinins), were found to potentiate contractile responses of this isolated airway segment to TES and exogenously applied capsaicin, substance P and neurokinin A. However, the magnitude of potentiation by either inhibitor was smaller for TES and capsaicin (less than 10-fold leftward shift) than for the substrate agonists (about 100-fold leftward shift). This quantitative difference in potentiation by NEP inhibitors does not appear to be due to an influence of vasoactive intestinal peptide or calcitonin gene-related peptide, two endogenous peptides that might be released concomitantly by TES. Neither peptide caused marked effects on contractile responses to TES or tachykinins when applied to the isolated tissues. Addition of inhibitors of serine proteases, aminopeptidases, acetylcholinesterase and angiotensin-converting enzyme failed to further potentiate responses to TES in the presence of thiorphan. Therefore, the contractile response does not appear to be further modified by the activity of these peptidases. Neuropeptide gamma, but not neuropeptide K, was potentiated by thiorphan. The data suggest that peptides that are not substrates for NEP (for example, neuropeptide K) may also be released by TES from capsaicin-sensitive neurons to cause contraction. This may, at least in part, explain the quantitative difference in potentiation by NEP inhibitors of contractile responses to TES and to exogenously applied NEP-sensitive tachykinins in the guinea pig hilar bronchus.
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PMID:Pharmacologic studies on the differential influence of inhibitors of neutral endopeptidase on nonadrenergic, noncholinergic contractile responses of the guinea pig isolated hilar bronchus to transmural electrical stimulation and exogenously applied tachykinins. 239 13

The effects of Met-enkephalinamide (MET-ENKamide) on brain temperature (Tb) and metabolic rate (MR) were assessed following direct administration into the preoptic/anterior hypothalamus (PO/AH) of freely moving rats. Bilateral microinjections of saline or MET-ENKamide (1-25 micrograms/microliter) were delivered through cannula guide tubes previously implanted in nine animals. Thiorphan, an enkephalinase inhibitor, was microinjected into the PO/AH of two of the animals. All injections were made remotely at an ambient temperature of 22 +/- 1 degree C in a volume of 1 microliter. Measurements of Tb (via a brain-dwelling thermistor) and MR were recorded continuously. The ability of naloxone to antagonize the effects of MET-ENKamide was investigated by fashioning a double-barreled injection cannula to fit within each guide tube; 1 microliter of saline or naloxone (1-10 micrograms) was delivered bilaterally into the PO/AH followed by 1 microliter of MET-ENKamide (25 micrograms) 5-10 min later. PO/AH administration of MET-ENKamide (1-25 micrograms) produced dose-dependent increases in Tb preceded by dose-dependent increases in MR, with a characteristic time course of approximately 30 min. Naloxone antagonized the rise in Tb and MR, either partially or completely, depending on dose. When administered alone, naloxone had no effect on Tb or MR. Microinjection of thiorphan (10 micrograms) into the PO/AH evoked increases in Tb and MR that were similar to those responses induced by MET-ENKamide. These results support a role for endogenous Met-enkephalin in the regulation of Tb in the rat.
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PMID:Changes in body temperature and metabolic rate following microinjection of Met-enkephalinamide in the preoptic/anterior hypothalamus of rats. 386 98

Thiorphan, a specific inhibitor of membrane neutral endopeptidase (NEP, EC 3.4.24.11) also known as the common acute lymphoblastic leukemia antigen (CALLA, CD10) was added into short-term clonal cultures of the buffy coat concentrates of human bone marrow obtained from a healthy donor (six experiments) and from ten patients with non-Hodgkin lymphoma (NHL) (eight in complete remission, one in partial remission and one in relapse). Thiorphan concentrations ranged from 10(-5) to 10(-13) M. Nanomolar and higher concentrations of the drug mildly stimulated the granulocyte-macrophage colony-forming unit (GM-CFU) counts in the cultures of normal bone marrow, reaching the significance at 10(-7) M. Meaningful alterations of the GM-CFU counts were noted in 31 of 79 thiorphan-treated cultures of NHL bone marrow (39%). In those cultures the stimulatory effects (33%) outnumbered the inhibitory ones (6%). The stimulatory effects occurred mainly in the bone marrow samples of the patients with highly malignant NHL. The observations are compatible with the idea that the membrane endopeptidase (CALLA, CD10) participates in processes controlling the proliferation and differentiation of hematopoetic cells by cleaving the neuropeptides and related hemoregulatory peptides.
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PMID:Thiorphan stimulates clonal growth of GM-CFU in short-term cultures of bone marrow from a healthy donor and from patients with non-Hodgkin lymphoma. 985 87

Intestinal metabolism and poor permeability were known to be major barriers for oral absorption of large peptide drugs. Dimensionless wall permeability values of C-terminal octa- and tetra-peptides cholecystokinin analogs (CCK8 and CCK4) were estimated and found out to be greater than 1, suggesting no permeability-limited absorption for CCK analogs. Thus, a strategy employing enzyme inhibitors and a specific delivery site to improve the absorption was developed and tested with CCK8, followed by identification of metabolites of the analogs and their participating enzymes in rabbit brush-border membrane vesicles. Thiorphan and amastatin, a specific enzyme inhibitor for enkephalinase and aminopeptidase, respectively, in pH 4 buffer solution were coadministered with CCK8 to the ileum in fistulated rats. The absolute bioavailability (F) of CCK8 was 5.4% and increased to 19% in the presence of the enzyme inhibitors, while the F values following oral administration were close to zero. These results indicate that peptide oral delivery is possible.
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PMID:Intestinal metabolism and absorption of cholecystokinin analogs in rats. 1192 13

1. Endothelin-1(1-31) (ET-1(1-31); 0.25 to 4 nmol kg(-1); i.v.) induced, in the guinea-pig, graded increases in MAP and an indomethacin-sensitive enhancement of pulmonary insufflation pressure (PIP). At all doses, ET-1(1-31) induced a monophasic pressor response, except at 4 nmol kg(-1), which caused a rapid and transient response (first phase: over first 10 min after injection) followed by a more slowly-developing and sustained (second phase: between 10 and 45 min after injection) increase in MAP. ET-1(1-31) was 4 to 10 fold less potent than ET-1 on PIP responses. 2. Phosphoramidon (5 and 10 mg kg(-1)) reduced both pressor and PIP effects of ET-1(1-31). Thiorphan (0.25 and 2.5 mg kg(-1)) did not affect the pressor responses to ET-1(1-31) although its PIP effects were markedly reduced by the NEP inhibitor. A selective endothelin-converting enzyme (ECE) inhibitor, CGS 35066 (1 mg kg(-1)), significantly reduced the second phase pressor response and increase in PIP triggered by ET-1(1-31). 3. The second (but not the first) pressor phase of ET-1(1-31) (4 nmol kg(-1)) was markedly reduced by BQ-123 (selective ET(A) antagonist), whereas the increase of PIP was significantly reduced by BQ-788 (selective ET(B) antagonist). Co-administration of BQ-123 plus BQ-788 abolished ET-1(1-31)-induced increase in PIP, but blockade of the second pressor phase afforded by BQ-123 was now reversed. 4. In guinea-pig isolated perfused lungs, ET-1(1-31) (50 nM) induced the release of prostacyclin and thromboxane A(2), which was inhibited by BQ-788 (5 nM) or thiorphan (25 microM), but not BQ-123 (1 microM). 5. These results suggest that ET-1(1-31) enhances MAP. Its sustained, but not transient, pressor effects are mediated via ET(A) receptor activation. Furthermore, ET-1(1-31) increases airway resistance in vivo and triggers prostacyclin and thromboxane A(2) release from perfused lungs predominantly via ET(B) receptor activation. ET-1(1-31) failed to display any selectivity of action towards either ET(A) or ET(B) receptors in these models. 6. We suggest that, in order to raise MAP, ET-1(1-31) requires conversion to ET-1, predominantly by ECE and to a lesser extent neutral endopeptidase 24.11, whereas the reverse holds true regarding its pharmacological effects in airways.
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PMID:Pressor and pulmonary responses to ET-1(1-31) in guinea-pigs. 1211 Jun 6

We investigated whether blood vessels contribute to the production of ET-1(1-31) from exogenous big endothelin-1 (BigET-1) in the rabbit and assessed which enzymes are involved in this process. Vascular reactivity experiments, using standard muscle bath procedures, showed that BigET-1 induces contraction in endothelium-intact rabbit aortic rings. Preincubation of the rings with phosphoramidon, CGS35066 or thiorphan reduced BigET-1-induced contraction. Conversely, chymostatin did not affect BigET-1-induced contraction. Thiorphan and phosphoramidon, but not CGS35066 or chymostatin, reduced ET-1(1-31)-induced contraction. None of the enzymatic inhibitors affected the contraction afforded by ET-1.BQ123-, but not BQ788-, selective antagonists for ET(A) and ET(B) receptors, respectively, produced concentration-dependent rightward displacements of the ET-1(1-31) and ET-1 concentration-response curves. By the use of enzymatic assays, we found that the aorta, as well as the heart, lung, kidney and liver, possess a chymase-like activity. Enzyme immunoassays detected significant levels of Ir-ET-1(1-31) in bathing medium of aortas after the addition of BigET-1 (30 nM). Neither thiorphan nor chymostatin altered the levels of Ir-ET-1(1-31). Conversely, the levels of Ir-ET-1(1-31) were increased in the presence of phosphoramidon. This marked increase of the 31-amino-acid peptide was abolished when phosphoramidon and chymostatin were added simultaneously. The major new finding of the present work is that the rabbit aorta generates ET-1(1-31) from exogenously administered BigET-1. Additionally, by measuring the production of ET-1(1-31), we showed that a chymase-like enzyme is involved in this process when ECE and NEP are inhibited by phosphoramidon. Our results also suggest that ET-1(1-31) is an alternate intermediate in the production of ET-1 following BigET-1 administration. Finally, we showed that NEP is the predominant enzymatic pathway involved in the cleavage of ET-1(1-31) to a bioactive metabolite that will act on ET(A) receptors to induce contraction in the rabbit aorta.
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PMID:Enzymatic pathways involved in the generation of endothelin-1(1-31) from exogenous big endothelin-1 in the rabbit aorta. 1663 56