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)

Incubation of the adrenal membranes at pH 3.5-5.6 resulted in apparent proteolysis of 140 kDa protein to yield a 70 kDa polypeptide containing an ANF-binding site, which could be photoaffinity labeled by [125I]4-azidobenzoyl monoiodo ANF-(4-28). This 70 kDa fragment was found to be disulfide-linked to the remaining segment(s) of the molecule, giving a total apparent Mr of 140,000 when not reduced. The acidic pH-dependent proteolysis was rapid even at 0 degree C, suggesting close association of an endopeptidase with ANF receptor. The proteolysis was inhibited by EDTA, but not by phenylmethanesulfonyl fluoride, N-ethylmaleimide or pepstatin, indicating that the enzyme is a metalloendopeptidase. The inhibition was reversed by ZnCl2 or MnCl2, but not CaCl2 or MgCl2. The adrenal membranes contained guanylate cyclase activity of 1.1 nmol/min/mg protein using Mn-GTP as a substrate, which could be stimulated by 0.1 microM ANF to 2.7 nmol/min/mg. The membranes showed high affinity to ANF-(1-28) and ANF-(4-28), but little affinity to the truncated peptides ANF-(5-25) and ANF-(7-23). After treatment at pH 3.5 and 0 degrees C for 15 min, the membranes retained ANF-binding activity but with broader specificity, exhibiting high affinity to all four peptides above. It was suggested that an acidic metalloendopeptidase in the adrenal membranes may be involved in ANF receptor cleavage.
 ...
PMID:Acidic pH- and metal ion (Zn++ or Mn++)-dependent proteolysis of 140 kDa atrial natriuretic factor receptor in bovine adrenal cortex plasma membranes: evidence for membrane-bound acidic metalloendopeptidase. 289 2

Pro-thyrotropin-releasing hormone (proTRH) is the precursor to thyrotropin-releasing hormone (TRH; pGlu-His-Pro-NH2), the hypothalamic releasing factor that stimulates synthesis and release of thyrotropin from the pituitary gland. Five copies of the TRH progenitor sequence (Gln-His-Pro-Gly) and seven cryptic peptides are formed following posttranslational proteolytic cleavage of the 26-kDa rat proTRH precursor. The endopeptidase(s) responsible for the physiological conversion of proTRH to the TRH progenitor form is currently unknown. We examined the in vitro processing of [3H]leucine-labeled or unlabeled proTRH by partially purified recombinant PC1. Recombinant PC1 processed the 26-kDa TRH precursor by initially cleaving the prohormone after the basic amino acid at either position 153 or 159. Based on the use of our well-established antibodies, we propose that the initial cleavage gave rise to the formation of a 15-kDa N-terminal peptide (preproTRH25-152 or pre-proTRH25-158) and a 10-kDa C-terminal peptide (pre-proTRH154-255 or preproTRH160-255). Some initial cleavage occurred after amino acid 108 to generate a 16.5-kDa C-terminal peptide. The 15-kDa N-terminal intermediate was further processed to a 6-kDa peptide (prepro-TRH25-76 or preproTRH25-82) and a 3.8-kDa peptide (preproTRH83-108), whereas the 10-kDa C-terminal intermediate was processed to a 5.4-kDa peptide (prepro-TRH206-255). The optimal pH for these cleavages was 5.5. ZnCl2, EDTA, EGTA, and the omission of Ca2+ inhibited the formation of pYE27 (preproTRH25-50), one of the proTRH N-terminal products, by 48, 82, 72, and 45%, respectively. This study provides evidence, for the first time, that recombinant PC 1 enzyme can process proTRH to its predicted peptide intermediates.
 ...
PMID:Pro-thyrotropin-releasing hormone processing by recombinant PC1. 759 40

The capillary endothelial cells of the median eminence represent a potential site for the degradation/modification of both circulating and hypothalamic peptides passing through the hypophysial portal system toward the pituitary. This study examines endothelial cell peptidase expression in vitro by monitoring the metabolism of gonadotropin-releasing hormone (GnRH) by cultured endothelial cells from sheep median eminence. Cleavage of GnRH by median eminence endothelial cell membranes generated GnRH1-5 as the primary stable product, which was then degraded to GnRH1-3 and free amino acids. Degradation of GnRH was completely inhibited by TPCK, ZnCl2 and N-ethylmaleimide, and partially inhibited by EDTA and by a specific inhibitor of the metalloendopeptidase EC 3.4.24.15, CFP-AAY-pAB. Interestingly, an increase in GnRH1-9 production was seen with the latter inhibitors, suggesting a two-step mechanism of GnRH degradation involving a primary cleavage at the Pro9-Gly10-NH2 bond, inhibitable by TPCK, ZnCl2, and NEM, followed by cleavage by EC 3.4.24.15 to generate GnRH1-5. Phosphoramidon and angiotensin converting enzyme inhibitors (as well as other non-specific inhibitors) were without effect, indicating that endopeptidase EC 3.4.24.11 and angiotensin converting enzyme are not involved. Neither bovine aortic endothelial cell nor AtT-20 cell membranes exhibited this pattern of peptidase activity. Degradation of GnRH by intact median eminence endothelial cells in culture was also observed, suggesting an extracellular orientation for these enzymes; the potential role of such peptidases in the fine regulation of both pituitary function and local blood flow is currently under investigation.
 ...
PMID:Characterization of membrane-associated peptidase activities expressed by endothelial cells of the ovine median eminence. 804 22

[D-Ala2,Leu5]Enkephalin was readily metabolized by membranes (40,000 g pellet) prepared from heads of the housefly, Musca domestica, with Gly3-Phe4 being the major site of cleavage. This hydrolysis was only partially inhibited (40%) by 10 microM phosphoramidon, an inhibitor of endopeptidase-24.11, but was almost totally abolished in the presence of a mixture of 10 microM phosphoramidon and 10 microM captopril, a potent inhibitor of mammalian angiotensin-converting enzyme (ACE). An assay for ACE employing Bz-Gly-His-Leu as the substrate was used to confirm the presence of an ACE-like peptidyl dipeptidase activity in fly head membranes. The peptidase had a Km of 1.91 mM for Bz-Gly-His-Leu and a pH optimum of 8.2. The activity was inhibited by 100 microM EDTA and was greatly activated by ZnCl2 but not other bivalent metal ions. Captopril, lisinopril, fosinoprilat and enalaprilat, all selective inhibitors of mammalian ACE, were also good inhibitors of the insect enzyme with IC50 values of 400 nM, 130 nM, 16 nM and 290 nM respectively. An M(r) value of around 87,000 was obtained for this enzyme from gel-filtration chromatography, indicating that the insect enzyme is similar in size to mammalian testicular ACE (M(r) = 90,000-110,000) and not the larger form of the enzyme (M(r) = 150,000-180,000) found in mammalian somatic tissues. The fly peptidyl dipeptidase was released from membranes into a soluble fraction by incubating the head membranes at 37 degrees C but not at 0 degree C, suggesting that the insect ACE-like enzyme can be solubilized from cell surfaces through the activity of a membrane-bound enzyme activity. In conclusion, we have shown the existence of a peptidyl dipeptidase in membranes from the heads of M. domestica, which has similar properties to those of mammalian ACE.
 ...
PMID:Identification and properties of a peptidyl dipeptidase in the housefly, Musca domestica, that resembles mammalian angiotensin-converting enzyme. 819 53

A phosphoramidon-sensitive endopeptidase activity has been identified in membranes prepared from heads of Musca domestica. The enzyme hydrolyses the Gly3-Phe4 bond of the enkephalin analogue [D-Ala2,Leu5]enkephalin and the Asn3-Phe4 bond of AKH I. Phosporamidon (10 microM), a selective inhibitor of mammalian endopeptidase 24:11, was able to fully protect AKH I from degradation by head membranes. The breakdown of [D-Ala2,Leu5]enkephalin was only partially inhibited by phosphoramidon (10 microM), suggesting the presence of other enkephalin-degrading enzymes in this preparation. The endopeptidase activity was inhibited by 1 mM EDTA and 1 mM 1,10-phenanthroline and could be partially re-activated in the presence of ZnCl2 but not other divalent metal ions. The enzyme had a neutral pH optimum and behaved like an integral membrane protein when subjected to phase-separation with Triton X-114. Although they have a number of similar properties, the insect and mammalian enzymes could be distinguished by their sensitivity to site-directed inhibitors of endopeptidase 24:11. The fly endopeptidase was much less sensitive to phosphoramidon (IC50, 0.25 microM), thiorphan (IC50, 2.5 microM), SQ 28603 (IC50, 1.0 microM), SCH 39370 (IC50, 2.5 microM) and SCH 32615 (IC50, 30 microM). The fly enzyme is indistinguishable from the endopeptidase activity that is enriched in locust synaptic membranes and that found in membranes from heads of Drosophila melanogaster. In summary, we have identified a rich source of an insect neutral metallo-endopeptidase which is similar to endopeptidase 24:11, an enzyme known to play a key role in the metabolism and inactivation of neuropeptides in mammals.
 ...
PMID:Metabolism of insect neuropeptides: properties of a membrane-bound endopeptidase from heads of Musca domestica. 837 13