Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.15.1 (ACE)
 18,300 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Antisera against a variety of vertebrate and invertebrate neuropeptides were used to map cerebral neurosecretory cells in the sphinx moth Manduca sexta. Intense immunoreactive staining of distinct populations of neurosecretory cells was obtained with antisera against locust adipokinetic hormone, bovine pancreatic polypeptide, FMRFamide, molluscan small cardioactive peptide (SCPB), leucine-enkephalin, gastrin/cholecystokinin, and crustacean beta-pigment dispersing hormone (beta PDH). Other antisera revealed moderate to weak staining. Each type of neurosecretory cell is immunoreactive with at least one of the antisera tested, and most of these neurons can be identified anatomically. The staining patterns provide additional information on the organization of cerebral neurosecretory cells in M. sexta. Based upon anatomical and immunocytochemical characteristics, 11 types of neurosecretory cells have been recognized in the brain, one type in the suboesophageal ganglion, and one in the corpus cardiacum. Extensive colocalization experiments show that many neurosecretory cells are immunoreactive with several different antisera. This raises the possibility that these cells may release mixtures of neuropeptides into the hemolymph, as has been demonstrated in certain other systems. The immunocytochemical data should be helpful in efforts to identify additional peptide neurohormones released from the brain of this and other insects.
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PMID:Peptide-immunocytochemistry of neurosecretory cells in the brain and retrocerebral complex of the sphinx moth Manduca sexta. 170 64

Considerable progress has been made in synthesizing peptide analogs with improved stability for probing function of peptide-receptor systems. However, since peptide ligands are usually unsuitable for development as potent orally active long-duration therapeutic agents, considerable research effort is being directed to the development of non-peptidal ligands. Roger Freidinger compares the lead compounds that have now been described in the opioid, CCK-gastrin and angiotensin II fields, and discusses the progress that has been made in other receptor fields. Most of the successes have been achieved through screening natural sources and synthetic collections. Rational design based on the natural peptide ligand has been more difficult, although ACE inhibitors have been effectively developed from a nonapeptide lead.
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PMID:Non-peptide ligands for peptide receptors. 254 66

ACE (angiotensin-converting enzyme; peptidyl dipeptidase A; EC 3.4.15.1), cleaves C-terminal dipeptides from active peptides containing a free C-terminus. We investigated the hydrolysis of cholecystokinin-8 [CCK-8; Asp-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2] and of various gastrin analogues by purified rabbit lung ACE. Although these peptides are amidated at their C-terminal end, they were metabolized by ACE to several peptide fragments. These fragments were analysed by h.p.l.c., isolated and identified by comparison with synthetic fragments, and by amino acid analysis. The initial and major site of hydrolysis was the penultimate peptide bond, which generated a major product, the C-terminal amidated dipeptide Asp-Phe-NH2. As a secondary cleavage, ACE subsequently released di- or tri-peptides from the C-terminal end of the remaining N-terminal fragments. The cleavage of CCK-8 and gastrin analogues was inhibited by ACE inhibitors (Captopril and EDTA), but not by other enzyme inhibitors (phosphoramidon, thiorphan, bestatin etc.). Hydrolysis of [Leu15]gastrin-(14-17)-peptide [Boc (t-butoxycarbonyl)-Trp-Leu-Asp-Phe-NH2] in the presence of ACE was found to be dependent on the chloride-ion concentration. Km values for the hydrolysis of CCK-8, [Leu15]gastrin-(11-17)-peptide and Boc-[Leu15]gastrin-(14-17)-peptide at an NaCl concentration of 300 mM were respectively 115, 420 and 3280 microM, and the catalytic constants were about 33, 115 and 885 min-1. The kcat/Km for the reactions at 37 degrees C was approx. 0.28 microM-1.min-1, which is approx. 35 times less than that reported for the cleavage of angiotensin I. These results suggest that ACE might be involved in the metabolism in vivo of CCK and gastrin short fragments.
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PMID:Novel activity of angiotensin-converting enzyme. Hydrolysis of cholecystokinin and gastrin analogues with release of the amidated C-terminal dipeptide. 255 81

A dipeptidyl carboxypeptidase, which cleaved the Gly3-Phe4 bond of enkephalins, was purified from guinea pig serum 420-fold. The optimum pH of the enzyme was in the neutral range (pH 7.25), and the molecular weight was estimated to be approx. 280,000. The enzyme hydrolyzed Met- and Leu-enkephalin with Km values of 0.30 and 0.50 mM, respectively. The enzyme was inhibited by metal chelators and p-chloro-mercuribenzoate. Captopril showed high inhibitory potency, while phosphoramidon and Phe-Ala showed no effect on the enzyme activity. Therefore, the obtained enzyme can be classified as an angiotensin-converting enzyme (EC 3.4.15.1). Among the bioactive peptides examined, bradykinin and angiotensin I were hydrolyzed by the enzyme. Angiotensin III showed a stronger inhibitory effect than that of angiotensin II. Substance P, gastrin I, and secretin were also inhibitory toward the enzyme activity. On high-performance liquid chromatography analysis, Met-enkephalin-Arg6-Phe7 and Leu-enkephalin-Arg6 were cleaved sequentially at the second peptide bond of the C terminus. Thus, the dipeptidyl carboxypeptidase in guinea pig serum may play a role not only in the angiotensin-bradykinin system but also in the metabolism of circulating enkephalins and other bioactive peptides.
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PMID:Enkephalin-degrading dipeptidyl carboxypeptidase in guinea pig serum: its properties and action on bioactive peptides. 299 Mar 46

We have previously shown that angiotensin I-converting enzyme (ACE) was expressed by epithelial cells of the rabbit gastric mucosa. In a search to obtain a cell model to study the regulation of ACE expression of gastric origin and its relationship with gastrin-cholecystokinin peptides, which have been proposed as ACE substrates, we investigated whether the HGT-1 human gastric cell line, which expresses gastrin, could also express ACE, using enzymatic and immunodetection methods as well as Northern-blot analysis and polymerase chain reaction. Results show that HGT-1 cells expressed a protein with a molecular weight of 130-140 kDa whose enzymatic and immunological properties were identical to those of ACE. More than 80% of ACE activity was found to be ectoenzymatic. However, immunocytochemical localization has mainly shown an intracellular localization, suggesting that most of intracytoplasmic ACE was not enzymatically active. In addition, Northern-blot analysis and polymerase chain reaction showed that the mRNA encoding that protein displayed a size and a sequence identical to those of somatic ACE. It therefore appears that the HGT-1 cell line could be a useful model to study both the regulation of gastric ACE and its interactions with gastrin-cholecystokinin peptides.
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PMID:Expression of angiotensin I-converting enzyme in the human gastric HGT-1 cell line. 857 43

Mammalian germinal angiotensin I-converting enzyme (gACE) is a single-domain dipeptidyl carboxypeptidase found exclusively in male germ cells, which has almost identical sequence and enzymic properties with the C-domain of the two-domain somatic ACE. Mutant mice that do not express gACE are infertile, suggesting a role for the enzyme in the processing of undefined peptides involved in fertilization. A number of spermatid peptides [e.g. cholecystokinin (CCK) and gastrin] are processed from pro-hormones by endo- and exo-proteolytic cleavages which might generate substrates for gACE. We have shown that peptide hormone intermediates with Lys/Arg-Arg at the C-terminus are high-affinity substrates for human gACE. gACE from human sperm cleaved Arg-Arg from the C-terminus of the CCK5-GRR (GWMDFGRR), a peptide corresponding to the C-terminus of a CCK-gastrin prohormone intermediate. Hydrolysis of CCK5-GRR by recombinant human C-domain ACE was Cl- dependent, with maximal activity achieved in 5-10 mM NaCl at pH 6.4. C-Domain ACE cleaved Lys/Arg-Arg from the C-terminus of dynorphin-(1-7), a pro-TRH peptide KRQHPGKR, and two insect peptides FSPRLGKR and FSPRLGRR. C-Domain ACE displayed high affinity towards all these substrates with Vmax/Km values between 14 and 113 times greater than the Vmax/Km for the conversion of the best known ACE substrate, angiotensin I, into angiotensin II. In conclusion, we have identified a new class of substrates for human gACE, and we suggest that gACE might be an alternative to carboxypeptidase E for the trimming of basic dipeptides from the C-terminus of intermediates generated from pro-hormones by subtilisin-like convertases in human male germ cells.
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PMID:Cleavage of arginyl-arginine and lysyl-arginine from the C-terminus of pro-hormone peptides by human germinal angiotensin I-converting enzyme (ACE) and the C-domain of human somatic ACE. 937 19

Our recent published studies suggest that angiotensin II (AII), generated and retained intracellularly, enhances growth of H4-II-E-C3 rat hepatoma cells, an average of 33%. Proliferation conferred by introduction of a plasmid [ Ang(-S)Exp/pSVL ] encoding a signal sequence-depleted angiotensinogen [Ang(-S)Exp] into these cells (which we have shown possess ACE and renin mRNAs) is mediated, at least in part, by enhanced PDGF-A chain mRNA production and protein secretion. The mitogenic effect is inhibited by losartan suggesting that it involves AII interaction with an AT(1)-like receptor. Introduction of anti-AII antibodies into the medium of these transfected cells has no effect upon growth of the cells, suggesting that AII is retained by the cells and that intracellular AII is growth stimulatory. In the present study, we sought to further characterize the intracellular localization and mode of action of Ang(-S)Exp. Consistent with our expectations, we now show that a fusion product of Ang(-S)Exp with green fluorescent protein [Ang(-S)Exp/EGFP], generated from an expression plasmid, is abundant and primarily cytoplasmic. Wild-type angiotensinogen/EGFP, in contrast, is only detectable following a cold-block (which acts to enhance folding-kinetics and slow secretion) and is largely restricted to the secretory pathway. We further show, using semi-quantitative RT/PCR that the long isoform of PDGF mRNA is elevated in Ang(-S)Exp transfected cells and in AII-treated naive cells but not in losartan-treated Ang(-S)Exp transfected cells. We identify C-terminal amidation recognition sites within the long-form protein (that are not present in the short-form) and show that these cells possess PAM (amidating enzyme precursor) and carboxypeptidase E mRNAs (the corresponding proteins of which are sufficient for amidation). Inhibitors of amidation inhibit growth of naive and Ang(-S)Cntr/ pSVL -transfected cells (2.6-fold for phenylbutenoic acid and 3.5-fold for disulfiram treatment) but more profoundly inhibit growth of Ang(-S)Exp/pSVL -transfected cells (6.7-fold for phenylbutenoic acid and 13-fold for disulfiram). In conclusion, these data confirm that signal sequence-depleted Ang(-S)Exp is retained within cells and is largely cytoplasmic. Because C-terminal amidation is absolutely required for full biological potency of a number of peptide hormones (including oxytocin, gastrin and calcitonin), we postulate that growth effects of both intracellular AII and exogenous AII can be conferred by PDGF long-form, possibly through an amidation-dependent mechanism.
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PMID:Intracellular angiotensin II increases the long isoform of PDGF mRNA in rat hepatoma cells. 1243 51

There are a number of licensed databases that assign biological activities to druglike compounds. The MDL Drug Data Report (MDDR), compiled from the patent literature, is a popular example. It contains several hundred distinct activities, some of which are therapeutic areas (e.g., Antihypertensive) and some of which are related to specific enzymes or receptors (e.g., ACE inhibitor). There are several data mining applications where it would be useful to calculate a similarity between any two activities. Two distinct activity labels can have a significant similarity for a number of reasons: two activities can be nearly synonymous (e.g., CCK B antagonist vs Gastrin antagonist), one activity may be a subset of another (e.g., Dopamine (D2) agonist vs Dopamine agonist), or an activity can be the mechanism by which another activity works (e.g., ACE inhibitor vs Antihypertensive), etc. In an ideal world, similarities for two activities could be calculated simply by comparing the compounds they have in common, but in hand-curated databases such as the MDDR the assignment of activities to compounds are inevitably inconsistent and incomplete. We propose a number of methods of calculating activity-activity similarities that hopefully compensate for errors in hand-curation. Two of these, TIMI and trend vector, show promise. Soft clustering of the activities using a union of similarity methods shows a reasonable association of therapeutic areas with their mechanisms.
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PMID:Calculating similarities between biological activities in the MDL Drug Data Report database. 1503 55