Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A membrane-bound metallo-endopeptidase that hydrolyzes human parathyroid hormone (1-84) and reduced hen egg lysozyme between hydrophilic amino acid residues was isolated from rat kidney [Yamaguchi et al. (1991) Eur. J. Biochem. 200, 563-571]. In this study, the hydrolyses of various peptide hormones and neuropeptides by the metallo-endopeptidase were examined using an automated gas-phase protein sequencer. The purified enzyme hydrolyzed the oxidized insulin B chain and substance P most rapidly, followed by big endothelin 1, neurotensin, angiotensin 1, endothelin 1, rat alpha-atrial natriuretic peptide and bradykinin, in this order. The enzyme mainly cleaved these peptides at bonds involving a hydrophilic amino acid residue. However, it cleaved bonds between less hydrophilic amino acid pairs in several short peptides, e.g. at the His5-Leu6 bond in oxidized insulin B chain, the Ile28-Val29 bond in big endothelin-1 and the Ile5-His6 and Phe8-His9 bonds in angiotensin 1. The enzyme cleavage sites of oxidized insulin B chain and angiotensin 1 were different from the reported sites cleaved by meprin and by endopeptidase 2, respectively. Kinetic determination of bradykinin hydrolysis by the purified enzyme yielded values of Km = 18.1 microM and kcat = 0.473 s-1, giving a ratio of kcat/Km = 2.62 x 10(4) s-1.M-1. The Km value was about 20-fold lower than that reported for meprin and endopeptidase 2. These results indicate that the membrane-bound metallo-endopeptidase from rat kidney is distinguished from meprin and endopeptidase 2 in its substrate specificity and is not parathyroid hormone specific, but has potential capacities to inactivate various biologically active peptide hormones and neuropeptides in vivo.
 ...
PMID:A membrane-bound metallo-endopeptidase from rat kidney. Characteristics of its hydrolysis of peptide hormones and neuropeptides. 137 51

Three different types of biotinylated endothelin 1 (ET-1) derivatives, [Cys1]-biotinylated ET-1, [Lys9]-biotinylated ET-1, and [Cys1][Lys9]-dibiotinylated ET-1, were obtained when the biotinylation reaction was carried out with sulfosuccinimidyl-6-(biotinamido)hexanoate in an aqueous solvent. The binding of [Lys9]-biotinylated ET-1 to the ET receptor was as efficient as that of natural ET-1, whereas the binding of either [Cys1]-biotinylated ET-1 or [Cys1][Lys9]-dibiotinylated ET-1 was significantly reduced. When ET-1 was reacted with succinimidyl-6-(biotinamido)hexanoate in an organic solvent, ET-1 was exclusively modified at lysine 9. The ET receptor was then isolated from human placenta by affinity chromatography with [Lys9]-biotinylated ET-1 and avidin-agarose. The purified ET receptor was active in ET binding and was resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis into two polypeptides with apparent molecular masses of 45 and 35 kDa. The NH2-terminal amino acid sequence indicated that the two polypeptides were from an identical subtype of the ET receptor (ETB, the ligand-nonselective type). A signal peptide from Met1 to Gly26 was missing from the 45-kDa ETB, whereas 64 amino acids at the NH2 terminus were missing from the 35-kDa ETB due to proteolytic cleavage which occurred between Arg64 and Ser65. Indeed, incubation of purified ETB with endopeptidase Arg-C resulted in degradation of the 45-kDa ETB, giving rise to the 35-kDa species by a specific cleavage at Arg64. The 35-kDa ETB was active in binding to ET-1, indicating that the NH2-terminal 64-amino-acid residues are not essential for ligand binding.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Biotin derivatives of endothelin: utilization for affinity purification of endothelin receptor. 145 57

Hydrolysis of endothelin 1 by rat kidney membranes was investigated using a reverse-phase HPLC and an automated gas-phase protein sequencer. Endothelin 1 was hydrolyzed into four major fragments which were detected by HPLC. Phosphoramidon, an inhibitor of neutral endopeptidase 24,11, almost completely suppressed the production of three fragments, but one fragment was not affected by the inhibitor. Analysis of N-terminal sequences of the degradation products revealed that the phosphoramidon-sensitive fragments were generated by cleavage at the Ser5-Leu6 bond of endothelin 1 that was identical with its cleavage site by purified rat endopeptidase 24,11, reported previously. The phosphoramidon-insensitive fragment was produced by cleavage at Leu17-Asp18, which was distinct from the sites by endopeptidase 24,11, but corresponded to that by a phosphoramidon-insensitive metallo-endopeptidase recently isolated from rat kidney membranes by us [(1992) Eur. J. Biochem. 204, 547-552]. Kinetic determination of endothelin 1 hydrolysis by the isolated enzyme yielded values of Km = 71.5 microM and kcat = 1.49 s-1, giving a ratio of kcat/Km = 2.08 x 10(4) s-1.M-1. The Km value was much higher and the kcat/Km value was much lower than those for rat endopeptidase 24,11 reported previously. Thus, endopeptidase 24,11 appears to hydrolyze endothelin 1 more efficiently than the isolated enzyme does. Both enzymes may play physiological roles in the metabolism of endothelin 1 by rat kidney membranes in vivo.
 ...
PMID:Endothelin 1 hydrolysis by rat kidney membranes. 151 1

The potent vasoconstrictor endothelin 1 (ET-1) is thought to arise from the proteolytic processing of big endothelin 1 (Big ET) by a unique endothelin-converting enzyme, possibly a metalloprotease. Experiments were conducted to determine the effects of Big ET on cardiovascular and renal functions during inhibition of metalloprotease activity in vivo. Intravenous infusion of Big ET (0.1 nmol.kg-1.min-1) in anesthetized euvolemic rats produced a significant increase in mean arterial pressure (MAP; 39 +/- 8%) and a decrease in effective renal plasma flow (ERPF; -39 +/- 2%), whereas glomerular filtration rate (GFR) remained unchanged (-8 +/- 8%). Simultaneous intravenous infusion of phosphoramidon (0.25 mg.kg-1.min-1), an inhibitor of metalloprotease activity including neutral endopeptidase EC 3.4.24.11 (NEP), completely prevented these effects of Big ET. Thiorphan (0.1 mg.kg-1.min-1), also an inhibitor of NEP, had absolutely no effect on either the renal or cardiovascular response to Big ET. Similarly, the response to Big ET was unaffected by infusion of enalaprilat (0.1 mg.kg-1.min-1), an inhibitor of the angiotensin-converting enzyme, which is also a metalloprotease. To determine whether the effect of phosphoramidon was due to antagonism of ET-1, an identical series of experiments was performed using ET-1 infusion (0.02 nmol.kg-1.min-1). Although the increase in MAP (24 +/- 5%) produced by ET-1 was less than that observed for the given dose of Big ET, the renal vasoconstriction was much more severe; the smaller peptide changed ERPF and GFR by -66 +/- 7 and -54 +/- 9%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Evidence for metalloprotease involvement in the in vivo effects of big endothelin 1. 165 Jan 47

When big endothelin-1 (big ET-1, 1-39) was incubated with the membrane fraction obtained from cultured endothelial cells (ECs) at pH 7.0 for 6 h, the immunoreactive (ir) ET in the reaction mixture was markedly increased. Phosphoramidon, a metalloproteinase inhibitor, as well as metal chelators specifically suppressed the above increase. Using reverse-phase high-performance liquid chromatography, ir-ET was confirmed to be ET-1[1-21]. In addition, we noted that the alterations in ET-1 correlated with those in the C-terminal fragment (CTF, 22-39) of big ET-1. When cultured ECs were incubated with phosphoramidon, time-dependent secretion of ET-1 and CTF from the cells was markedly suppressed. In contrast, the secretion of big ET-1 was increased by phosphoramidon. Thiorphan, a specific inhibitor of neutral endopeptidase 24.11, was without effect on the secretion of ET-related peptides. Moreover, phosphoramidon potently inhibited the hypertensive effect of big ET-1 without affecting the ET-1-induced hypertension in anesthetized rats. From these findings, it seems reasonable to consider that phosphoramidon-sensitive and membrane-bound metalloproteinase, which is not a neutral endopeptidase 24.11, is the most plausible candidate for big ET-1-converting enzyme in vivo.
 ...
PMID:Conversion of big endothelin-1 to endothelin-1 by phosphoramidon-sensitive metalloproteinase derived from aortic endothelial cells. 172 35

We found that immunoreactive endothelin (ET) is present in seminal fluid in very large amounts (500-5000 ng/L; quantification based on ET-1 standard). This immunoreactive ET was detected by use of a radioimmunoassay system in which the N-terminal portion of ET-1 and ET-2 (and big ET-1 and big ET-2) are recognized. Thus, the immunoreactive ET in seminal fluid may include the precursors of ET-1 or ET-2 (i.e., big ET) as well as metabolites of ET-1 or ET-2 in which the N-terminal region is intact. The levels of immunoreactive ET in seminal fluid from men with normal semen analyses and that in seminal fluid of vasectomized men were within the same range. Using a different radioimmunoassay system in which the C-terminal portion of ET-1, ET-2, and ET-3 is recognized, we found that the levels of immunoreactive ET were much lower (or undetectable). We speculate that bioactive ET may be produced and act to promote sperm transport in the male reproductive tract; thereafter, bioactive ET may be metabolized by membrane metalloendopeptidase (which is present in male reproductive tissues and semen) to immunoreactive, inactive products. Alternatively, big ET in seminal fluid may be processed in tissues of the female internal genitalia to bioactive ET, which could act to promote sperm transport through the uterine cavity by stimulating myometrial contractions.
 ...
PMID:Massive amounts of immunoreactive endothelin in human seminal fluid. 172 24

Intravenous injections of big endothelin (ET)-1 (700 pmol/kg) in the pig increased arterial plasma levels of ET-1-like immunoreactivity (ET-1-LI) from 11.1 +/- 0.7 pM to 46.3 +/- 6.7 pM in the control situation and from 11.5 +/- 0.4 pM to 58.2 +/- 17 pM in the presence of the neutral endopeptidase inhibitor phosphoramidon (3 mg/kg). Big ET-1 increased splenic vascular resistance by 29% in the control situation. The vasoconstriction evoked by big ET-1 in the spleen was reduced after phosphoramidon treatment whereas the elevation of arterial ET-1-LI was not influenced. Furthermore the splenic vasoconstriction evoked by ET-1 was reduced after phosphoramidon without influencing plasma ET-1-LI. Also in rats the pressor effect of big ET-1 (1 nmol/kg) was inhibited by phosphoramidon (5 mg/kg) whereas the elevation of plasma ET-1 was not influenced. It is concluded that the vasoconstrictor effects of both big ET-1 and ET-1 are inhibited, but the increase in plasma ET-1 is unaffected by phosphoramidon.
 ...
PMID:Phosphoramidon inhibits the vasoconstrictor effects evoked by big endothelin-1 but not the elevation of plasma endothelin-1 in vivo. 194 66

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.
 ...
PMID:Vascular A10 cell membranes contain an endothelin metabolizing neutral endopeptidase. 201 30

Incubation of endothelins (ETs) with bovine kidney neutral endopeptidase (NEP) resulted in a selective two-step degradation with loss of biochemical activity. The Km of the enzyme indicated high-affinity binding, and hydrolysis was completely inhibited by phosphoramidon. The first step was nicking of the Ser5-Leu6 bond, followed by cleavage at the amino side of Ile19. The nicked peptide exhibited biochemical activities comparable to those of the intact peptide--i.e., binding to the ET receptor, induction of inositol phospholipid hydrolysis, and toxicity. The twice-cleaved product was inactive. The sarafotoxins (SRTXs) were more resistant than the ETs to NEP: for example, the half-time for ET-1 was approximately 1 hr, while it was approximately 4 hr for SRTX-b and even higher for SRTX-c. These in vitro findings may indicate a regulatory role of NEP (or similar enzymes) in the physiological inactivation of ETs. They might also help to explain why under certain physiological conditions ETs may be less toxic than SRTXs.
 ...
PMID:Endothelins are more sensitive than sarafotoxins to neutral endopeptidase: possible physiological significance. 219 Dec 99

Novel endothelin converting enzyme (ECE) inhibitors, WS75624 A and B, have been isolated from the fermentation broth of Saccharothrix sp. No. 75624. These inhibitors were purified from an acetone extract of whole culture broth followed by HP-20 column chromatography, silica gel column chromatography and HPLC. WS75624 A and B showed highly potent ECE inhibitory activity, and both had IC50 values of 0.03 microgram/ml. WS75624 A and B also showed other metalloprotease (collagenase and neutral endopeptidase) inhibitory activity with IC50 values of 1 microgram/ml. Since large amount of WS75624 B was isolated, we tried in vivo evaluation using WS75624 B. WS75624 B inhibited big endothelin-induced pressor effect when administered to SD rat intravenously with big ET-1.
 ...
PMID:WS75624 A and B, new endothelin converting enzyme inhibitors isolated from Saccharothrix sp. No. 75624. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities. 749 Feb 8


1 2 3 4 5 6 7 8 Next >>