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

The membrane metalloenzyme endopeptidase-24.11 has been localized by immunocytochemistry in the porcine hippocampus in the stratum oriens and stratum radiatum. Endopeptidase-24.11 was found to be approximately 10-fold more abundant in a striatal than a hippocampal membrane preparation. Both somatostatin-28 and somatostatin-14 were metabolized by endopeptidase-24.11, but the kinetics of hydrolysis markedly favoured the smaller form of the neuropeptide. After phase separation with Triton X-114 of striatal and hippocampal membrane preparations, and by using selective inhibitors, the major (> 80%) somatostatin-metabolizing activity was found to partition into the detergent-rich phase and was attributable predominantly to endopeptidase-24.11. The residual activity observed in the presence of the selective endopeptidase-24.11 inhibitor phosphoramidon was blocked by Pro-Ile or N-[1-(RS)-carboxy-3-phenylpropyl]-Ala-Ala-Phe-p-aminobenzoate, inhibitors of endopeptidase-24.16 and endopeptidase-24.15, respectively. However, Pro-Ile, at comparable concentrations, was shown to inhibit endopeptidase-24.11, challenging the validity of its use as a selective inhibitor of endopeptidase-24.16. The immunocytochemical and Triton X-114 phase-separation data implicate endopeptidase-24.11, rather than endopeptidase-24.16 or endopeptidase-24.15, as the major physiological somatostatin-degrading neuropeptidase in the striatum and hippocampus.
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PMID:Endopeptidase-24.11 is the integral membrane peptidase initiating degradation of somatostatin in the hippocampus. 789 Nov 11

Several neuropeptides, including neurotensin, somatostatin, bradykinin, angiotensin II, substance P, and luteinizing hormone-releasing hormone but not vasopressin and oxytocin, were actively metabolized through proteolytic degradation by cultivated astrocytes obtained from rat cerebral cortex. Because phenanthroline was an effective degradation inhibitor, metalloproteases were responsible for neuropeptide fragmentation. Neurotensin was cleaved by astrocytes at the Pro10-Tyr11 and Arg8-Arg9 bonds, whereas somatostatin was cleaved at the Phe6-Phe7 and Thr10-Phe11 bonds. These cleavage sites have been found previously with endopeptidases 24.16 and 24.15 purified from rat brain. Addition of specific inhibitors of these proteases, the dipeptide Pro-Ile and N-[1-(RS)-carboxy-3-phenylpropyl]-Ala-Ala-Phe-4-aminobenzoate, significantly reduced the generation of the above neuropeptide fragments by astrocytes. The presence of endopeptidases 24.16 and 24.15 in homogenates of astrocytes could also be demonstrated by chromatographic separations of supernatant solubilized cell preparations. Proteolytic activity for neurotensin eluted after both gel and hydroxyapatite chromatography at the same positions as found for purified endopeptidase 24.16 or 24.15. In incubation experiments or in chromatographic separations no phosphoramidon-sensitive endopeptidase 24.11 (enkephalinase) or captopril-sensitive peptidyl dipeptidase A (angiotensin-converting enzyme) could be detected in cultivated astrocytes. Because astrocytes embrace the neuronal synapses where neuropeptides are released, we presume that the endopeptidases 24.16 and 24.15 on astrocytes are strategically located to contribute significantly to the inactivation of neurotensin, somatostatin, and other neuropeptides in the brain.
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PMID:Endopeptidases 24.16 and 24.15 are responsible for the degradation of somatostatin, neurotensin, and other neuropeptides by cultivated rat cortical astrocytes. 790 52

1. The degradation of tritiated and unlabelled neurotensin (NT) following close intra-arterial infusion of the peptides in ileal segments of anaesthetized dogs was examined. 2. Intact NT and its catabolites recovered in the venous effluents were purified by chromatography on Sep-Pak columns followed by reverse-phase h.p.l.c. and identified by their retention times or by radioimmunoassay. 3. The half-life of neurotensin was estimated to be between 2 and 6 min. Four labelled catabolites, corresponding to free tyrosine, neurotensin (1-8), neurotensin (1-10) and neurotensin (1-11), were detected. 4. Neurotensin (1-11) was mainly generated by a phosphoramidon-sensitive cleavage, probably elicited by endopeptidase 24-11. 5. Two endopeptidase 3.4.24.16 inhibitors, phosphodiepryl 03 and the dipeptide Pro-Ile, dose-dependently potentiated the recovery of intact neurotensin. Furthermore, both agents inhibited the formation of neurotensin (1-10), the product that results from the hydrolysis of neurotensin by purified endopeptidase 3.4.24.16. In contrast, the endopeptidase 3.4.24.15 inhibitor Cpp-AAY-pAB neither protected neurotensin from degradation nor modified the production of neurotensin (1-10). 6. Our study is the first evidence to indicate that endopeptidase 3.4.24.16 contributes to the catabolism of neurotensin, in vivo, in the dog intestine.
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PMID:Role of endopeptidase 3.4.24.16 in the catabolism of neurotensin, in vivo, in the vascularly perfused dog ileum. 803 33

The loop from Ile-226 to Arg-241 in the glutathione synthetase (GSHase) from Escherichia coli B is rich in glycine and alanine and too flexible to take a fixed conformation [Yamaguchi, H., Kato, H., Hata, Y., Nishioka, T., Kimura, A., Oda, J., & Katsube, Y. (1993) J. Mol. Biol. 229, 1083-1100; Tanaka, T., Kato, H., Nishioka, T., & Oda, J. (1992) Biochemistry 31, 2259-2265]. To restrict the flexibility, three residues in the loop, Pro-227, Gly-229, and Gly-240, were replaced with alanine and valine residues. Variability in conformations of the mutant loops and shifts in the distribution of conformers between the open and closed states were assessed by steady-state kinetics, X-ray crystallographic structure analysis, and proteolysis with arginyl endopeptidase. Mutant enzymes replaced with a valine residue at the basal positions of the loop (P227V, G240V, and P227V/G240V) were identical with the wild-type enzyme in their crystal structures, except the loop region. The mutant loops retained apparent conformational variability, so as to take the open and closed states and to protect the acyl phosphate intermediate from the decomposition uncoupled from glutathione synthesis, but lost the catalytic activity; Kmapp values for glycine and gamma-Glu-Cys were sensitive to the mutations and drastically increased, and the k0app value was fatally reduced in the P227V/G240V mutant enzyme. The present results suggest that adjustability of the loop to the closed state is required for the recognition of the substrates, gamma-Glu-Cys and glycine, and for the chemical interactions with the bound substrates.
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PMID:Flexibility impaired by mutations revealed the multifunctional roles of the loop in glutathione synthetase. 824 Nov 29

Rabbit neutral endopeptidase-24.11 is a type II transmembrane protein with a 27-amino acid residue positively charged NH2-terminal cytoplasmic domain, a 23-amino acid residue hydrophobic signal peptide/membrane anchor domain, and a large catalytic COOH-terminal domain exposed on the exoplasmic side of the membrane. In order to study the mechanism of membrane anchoring of neutral endopeptidase-24.11, we created mutants in which the cytoplasmic tail was deleted. Expression of these mutants in COS-1 cells resulted in the secretion of approximately 10-20% of the protein into the culture medium, due possibly to the cleavage of part or all of the signal peptide/membrane anchor domain by the rough endoplasmic reticulum signal peptidase. In a second set of mutants, a hydrophilic sequence (GSQNS) was inserted midway in the signal peptide/membrane anchor domain of neutral endopeptidase-24.11. When this hydrophilic sequence was introduced into the full-length neutral endopeptidase-24.11, approximately 20% of the enzyme activity was recovered in the culture medium. This proportion increased to 93% when the cytosolic tail was deleted. Sequencing of the [3H]tyrosine- or [3H]isoleucine-labeled secreted protein indicated that proteolysis, possibly by signal peptidase, occurred on the COOH-terminal side of the signal peptide/membrane anchor domain. We conclude that the efficient cleavage of the signal peptide/membrane anchor domain and secretion of the protein require both the deletion of the cytosolic domain and the presence of a hydrophilic sequence.
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PMID:Transformation of the signal peptide/membrane anchor domain of a type II transmembrane protein into a cleavable signal peptide. 842 44

Peptide hormone inactivating endopeptidase (PHIE) is a metalloendopeptidase which was isolated from the skin granular gland secretions of Xenopus laevis [Carvalho, K. M., Joudiou, C., Boussetta, H., Leseney, A. M., & Cohen, P. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 84-88]. This peptidase exhibits a thermolysin-like character and hydrolyzes bonds on the amino terminus of hydrophobic amino acids, performing cleavage of Xaa-Phe, Xaa-Leu, Xaa-Ile, Xaa-Tyr, and Xaa-Trp doublets. When the enzyme recognized a doublet of hydrophobic amino acids such as Phe6-Phe7 of somatostatin-14, Phe7-Phe8 of substance P, Phe4-Leu5 of [Leu5,Arg6]enkephalin, and Tyr4-Ile5 of angiotensin II, cleavage occurred preferentially between these residues. The use of selectively modified carboxy-terminal octapeptide fragments of atrial natriuretic factor (ANF) indicated that the enzyme tolerates as substrates only peptides bearing a P'1 bulky hydrophobic amino acid residue. Although a P'1 hydrophobic residue was a necessary condition, it was found in a number of peptides that all potential cleavage sites were not recognized by the enzyme. These data suggested that this metalloendoprotease requires for its thermolysin-like activity a preferred conformation of the peptide chain. Kinetic results obtained using a series of related substrates derived from biologically active peptides of the atrial natriuretic factor, tachykinin, and enkephalin families indicated the presence of an extended binding site accommodating at least six amino acid residues, in contrast to thermolysin (EC 3.4.24.4) and neutral endopeptidase (NEP; EC 3.4.24.11), which hydrolyze shorter homologous peptides.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Characterization of the thermolysin-like cleavage of biologically active peptides by Xenopus laevis peptide hormone inactivating enzyme. 850 36

Lysosomal cathepsin B but not L degraded rAPP751 to yield C-terminal 19-25 kDa fragments containing beta A4, reinforcing the view that acidic proteases participate in endosomal-lysosomal processing to yield amyloidogenic fragments in situ. This mechanism is consistent with fragmentation of endogenous APPs within clathrin-coated vesicles (CVs) by vesicular hydrolases, with the appearance of C-terminal amyloidogenic fragments following incubation at pH 6.5. A neutral endopeptidase resembling NEP 24.11 (PS-NEP) purified from detergent extracts of human brain degraded rAPP751; however, breakdown was not blocked robustly by metal chelators or phosphoramidon, suggesting the presence of an alternative processing enzyme. Effects of other inhibitors showed that breakdown was mediated by serine-protease-like component(s). A phosphoramidon-insensitive metalloendopeptidase (PI-NEP) partially purified from rat brain P2 using detergents, and resembling NEP 24.15, showed no activity towards rAPP751. Peptides containing putative beta- or gamma-secretase sites were synthesized for purposes of examining their metabolism by the brain enzymes. Those containing beta-secretase sites were hydrolysed at one or more sites by the four enzymes, but only PI- and PS-NEP acted at the Met-Asp site of Ac-Val-Lys-Met-Asp-Ala-Glu-Phe-Arg.NH2. In the case of substrates containing the gamma-site, these two categories of enzymes were the only ones degrading N-Ac-Ile-Ala.NH2. These data imply that the brain metalloendopeptidases, while inactive towards intact precursors, may be involved in turnover of intermediates containing beta- or gamma-sites.
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PMID:Brain cathepsin B but not metalloendopeptidases degrade rAPP751 with production of amyloidogenic fragments. Comparison with synthetic peptides emulating beta- and gamma-secretase sites. 853 84

We have previously identified in membranes of the locomotory muscle of Ascaris suum a phosphoramidon-sensitive endopeptidase which hydrolyses the neuropeptide AF1 (Lys-Asn-Glu-Phe-Ile-Arg-Phe-NH2) by cleavage of the Glu3-Phe4 bond (Sajid & Isaac, 1994). We have determined the properties of this neuropeptide-degrading enzyme of A. suum muscle using AKH-1 (pGlu-Leu-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2) and [D-Ala2, Leu5]enkephalin as convenient endopeptidase substrates. Phosphoramidon, thiorphan and SQ 28603, potent inhibitors of mammalian neprilysin (neutral endopeptidase, endopeptidase 24.11), inhibited the endopeptidase activity towards AKH-I with IC50 values of 0.13 microM, 22 microM and 6.3 microM, respectively. Two other neprilysin inhibitors (SCH 32615 and SCH 39370) and the bivalent metal ion chelators, EDTA (1 mM) and 1, 10 bis-phenanthroline (1 mM) failed to inhibit the nematode enzyme. The endopeptidase had a neutral pH optimum and a significant proportion (45%) of the enzyme activity partitioned into the detergent-rich phase of Triton X-114, indicating that the enzyme is an integral membrane protein. The muscle enzyme also attacked [D-Ala2, Leu5]enkephalin cleaving the Gly3-Phe4 bond and this hydrolytic activity was inhibited by phosphoramidon and thiorphan (IC50, 0.28 microM and 15.8 microM, respectively) but not by EDTA and 1, 10 bis-phenanthroline. The phosphoramidon-sensitive endopeptidase activity was detected on intact muscle cells prepared by collagenase treatment of the body wall musculature, indicating that endopeptidase is accessible to peptide molecules that interact with the cell surface.
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PMID:Identification and properties of a neuropeptide-degrading endopeptidase (neprilysin) of Ascaris suum muscle. 855 93

T-kinin (Ile-Ser-bradykinin), the product of T-kininogen, has been found in rat plasma during systemic inflammation, but the effect of this kinin on airway inflammatory response is unknown. We examined the effect of T-kinin on vascular permeability in airways of anesthetized rats in vivo by using photometric measurement of the extravasated Evans blue. Intravenous injection of T-kinin (0.1-10 mumol/kg) increased dye extravasation in a dose-dependent manner, with 134% for trachea and 117% for bronchi by 1 mumol/kg. Pretreatment with bradykinin B2-receptor antagonist Hoe-140 (100 nmol/kg), but not the B1-receptor antagonist des-Arg9-Leu8-bradykinin (5 mg/kg), abolished plasma extravasation evoked by T-kinin (1 mumol/kg). NK1 tachykinin-receptor antagonist CP-99994 (4 mg/kg) did not affect T-kinin-induced vascular leakage. Pretreatment with captopril (2.5 mg/kg), angiotensin-converting enzyme inhibitor, potentiated T-kinin (100 nmol/kg)-induced plasma extravasation, whereas phosphoramidon (2.5 mg/kg), a neutral endopeptidase inhibitor, had no effect. We conclude that T-kinin produces airway vascular extravasation via stimulation of B2 receptors. The effect is modulated by endogenous angiotensin-converting enzyme and is not mediated via activation of sensory nerve.
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PMID:Effect of T-kinin on microvascular permeability and its modulation by peptidases in rat airways. 856 53

Angiotensins (angiotensin I, angiotensin II, angiotensin II-amide) have been isolated in leeches and such peptides are involved in diuresis in these animals. To explore possible inactivation mechanisms of these peptides, angiotensins were incubated with head membranes of the leech T. tessulatum. Membranes derived from head parts of this leech are very rich in peptidases. They contain endopeptidase-24.11-like enzyme (NEP-like) associated with a battery of exopeptidase. The way that angiotensins are degraded by the combined attack of these membrane peptidases has been investigated. The contribution of individual peptidases was assessed by adding inhibitors (phosphoramidon, captopril and amastatin) to the membrane fractions, when they were incubated with the peptides. In the case of angiotensin I, the primary attack was performed by a combined action of the NEP-like and the ACE-like enzymes, followed by aminopeptidase attacks. Angiotensin II and III were hydrolyzed by NEP-like enzyme at the same Tyr-Ile bond, whereas the N-terminal arginine residue of angiotensin III was removed by an arginyl aminopeptidase. These results show that angiotensins are efficiently degraded by membranes and that NEP-like enzyme plays a key role in this process.
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PMID:Metabolism of angiotensins by head membranes of the leech Theromyzon tessulatum. 861 6


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