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)

The membrane-bound form of aminopeptidase P (aminoacylprolyl-peptide hydrolase) (EC 3.4.11.9) was purified to apparent homogeneity from bovine lung microsomes. The enzyme was solubilized using phosphatidylinositol-specific phospholipase C (Bacillus thuringiensis), indicating that bovine lung amino-peptidase P is attached to membranes via a glycosylphosphatidylinositol anchor. The enzyme was purified 1900-fold with a yield of 25% by chromatography on decyl-agarose, omega-aminodecyl-agarose, a second decylagarose column, DEAE-Sephacel, and an ultrafiltration step. Native gradient polyacrylamide gel electrophoresis revealed a single stained protein band whose position in the gel corresponded to cleavage of the Arg1-Pro2 bond of bradykinin. The Mr was 360,000 by gel permeation chromatography and 95,000 by reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The substrate specificity of aminopeptidase P was determined using approximately 50 peptides with proline in the second position. The enzyme could hydrolyze lower NH2-terminal homologs of bradykinin, including Arg-Pro-Pro, which was used as the routine substrate in a rapid fluorescence assay performed in the absence of added Mn2+. Some peptides having NH2-terminal amino acids other than arginine were also cleaved. Aminopeptidase P appeared to favor peptides that had 2 proline residues or proline analogs in positions 2 and 3 of the substrate. In general, tripeptides having a single proline residue in position 2 were poor substrates. Aminopeptidase P was inhibited by a series of peptides, 3-8 residues long, having an NH2-terminal Pro-Pro sequence. The enzyme was also inhibited by metal-chelating agents, 2-mercaptoethanol (4 mM), p-chloromercuribenzenesulfonic acid, and NaCl at concentrations greater than or equal to 0.25 M. The purified enzyme had a pH optimum of 6.5-7.0 and was most stable in the basic pH range. A role for membrane-bound aminopeptidase P in the pulmonary inactivation of circulating bradykinin is proposed.
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PMID:Membrane-bound aminopeptidase P from bovine lung. Its purification, properties, and degradation of bradykinin. 153 67

Aminoacylproline hydrolase (EC 3.4.11.9) of guinea pig serum has been obtained as two apparently homogeneous isoforms. Dialyzed serum was chromatographed successively on Affi-gel blue, hydroxyapatite, DE-cellulose, phenyl-Sepharose, an affinity matrix for angiotensin converting enzyme and concanavalin-Sepharose. On the latter matrix, 68% of the enzyme activity was eluted with alpha-methyl mannoside at 10 and 100 mM, and 29% was eluted with alpha-methyl glucoside, 500 mM, at 56 degrees C. The two fractions ('biantennary' and 'high mannose' fractions, respectively) were concentrated and then chromatographed separately on Sephacryl S-200HR. Both fractions were eluted as expected for a globular protein of Mr 217,000. On SDS-PAGE, under reducing and non-reducing conditions, each of the concanavalin-Sepharose fractions was separated into two protein bands, Mr 89,000 and Mr 81,500. Each of the bands was found to be N-blocked when N-terminal amino acid sequencing was attempted. The reaction of the 'biantennary' fraction with the synthetic substrate Arg-Pro-Pro-[3H]benzylamide was characterized in part: Km 0.7 microM, kcat 124.6 min-1, kcat/Km 1.78.10(8) M-1 min-1. Hydrolysis of the substrate was strongly inhibited by bradykinin and those of its lower homologs that contain two adjacent proline residues. Cu2+ was strongly inhibitory. Co2+ at 30 microM activated the enzyme, as did Mn2+, Mg2+ and Ca2+ at higher concentrations. Sulfhydryl compounds, including captopril, inhibited the enzyme as did 1,10-phenanthroline. Iodoacetamide and N-ethylmaleimide had no effects, but 4-hydroxymercuribenzoate conferred a partial inhibition over a remarkably wide concentration range: 0.34-1400 microM. Amastatin and bestatin did not inhibit the enzyme. Aminoacylproline hydrolase of guinea pig serum appears to be a heterogeneous, glycosylated metallo-enzyme with a high affinity for bradykinin and related peptides in which the sequence Pro-Pro, Xaa-Pro-Pro or Xaa-Pro-Hyp is N-terminal.
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PMID:Purification and characterization of guinea pig serum aminoacylproline hydrolase (aminopeptidase P). 154 Jun 46

The venom of the Brazilian snake Bothrops jararacussu, was found to contain peptides capable of potentiating the smooth muscle contracting activity of bradykinin (BK). Chromatographic separation on Sephadex G-25 and Sephadex G-10 respectively, yielded an active peptide which at a concentration of 0.6 micrograms/ml doubled the effect of a single dose of BK on the isolated guinea-pig ileum. HPLC chromatography showed this material to contain one major and 4 minor components. The active peptide was 2-3 times more active than Captopril in the potentiation of the effects of BK on rat arterial blood pressure and on the isolated guinea pig ileum. It also showed marked capacity to inhibit angiotensin I-converting enzyme.
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PMID:Biologically active peptides from Bothrops jararacussu venom. 160 44

L-158,809 (5,7-dimethyl-2-ethyl-3-[[2'-(1H-tetrazol-5yl)[1,1']-bi- phenyl-4-yl]-methyl]-3H-imidazo[4,5-b]pyridine) is a potent, competitive and specific antagonist of AT1 subtype of angiotensin II (AII) receptors in in vitro radioligand binding and functional isolated tissue assays. The present study was carried out to characterize the in vivo pharmacology of this potent AII receptor antagonist. In conscious, normotensive and anesthetized pithed rats, L-158,809 inhibits AII (0.1 microgram/kg i.v.) elevations in blood pressure without altering pressor responses to methoxamine or arginine vasopressin. In conscious rats, the relative potencies (ED50) were 29 micrograms/kg i.v. and 23 micrograms/kg p.o. Duration of action with single i.v. or p.o. doses exceeded 6 hr in rats. In similar experiments using rhesus monkeys, the potencies of L-158,809 were 10 micrograms/kg i.v. and approximately 100 micrograms/kg p.o. In these rats and monkeys, L-158,809 was 10 to 100 times more potent than DuP-753 (losartan) and approximately 3 times more potent than the metabolite, EXP3174. AII-induced elevation of plasma aldosterone in rats was also inhibited by L-158,809. Unlike angiotensin converting enzyme inhibitors, L-158,809 did not potentiate the hypotensive responses to i.v. bradykinin. L-158,809 was antihypertensive in high renin hypertensive rats (aortic coarction) and volume-depleted rhesus monkeys. The maximum hypotensive responses with acute doses of L-158,809 were equal to those with an angiotensin converting enzyme inhibitor in these renin-dependent animal models. From these in vivo data, L-158,809 is a selective AII receptor antagonist with high potency, good p.o. absorption, long duration and antihypertensive efficacy equal to angiotensin converting enzyme inhibition after single doses.
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PMID:In vivo pharmacology of L-158,809, a new highly potent and selective nonpeptide angiotensin II receptor antagonist. 162 93

ACE inhibitors (ACEIs) have now been shown to improve symptoms and survival in patients with mild, moderate and severe chronic heart failure. Their mechanism of action is thought to be a combination of RAAS suppression and augmentation of bradykinin and prostaglandins. Although ACE inhibitors improve hemodynamics post myocardial infarction, we do not yet have consistent data on their effects on symptoms or survival in these particular patients. One other potential benefit is their effects on reperfusion injury and free radicals. As yet only minor differences have been found to exist between different ACEIs but increasing attention is now being focussed in this direction.
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PMID:The clinical pharmacology of angiotensin converting enzyme inhibitors in chronic heart failure. 164 5

Effects of imidapril hydrochloride ((-)-(4S)-3-[(2S)-2-[[(1S)-1- ethoxycarbonyl-3-phenylpropyl]amino]propionyl]-1-methyl-2- oxoimidazolidine-4-carboxylic acid hydrochloride, imidapril, TA-6366, CAS 89396-94-1), a new prodrug type angiotensin converting enzyme (ACE) inhibitor, and 6366 A (CAS 89371-44-8), an active metabolite of imidapril, on isolated vascular preparations were studied. 6366 A inhibited angiotensin I (AT-I)-induced contraction of the rabbit thoracic aorta at 3 x 10(-10) mol/l or more and augmented bradykinin (BK)-induced relaxation of the dog renal artery precontracted with prostaglandin F2 alpha PGF2 alpha at 10(-9) mol/l or more, whereas imidapril at 10(-7) mol/l did not affect these responses. However, 6366 A, like imidapril, had no effect on angiotensin II (AT-II), norepinephrine, serotonin-, KCl- and PGF2 alpha-induced contractions. The inhibitory effect of 6366 A on AT-I-induced contraction was attenuated by denudation of the endothelium, but it was still maintained even after washing out the aorta that had been previously exposed to the medium containing 6366 A. This suggests that 6366 A persistently inhibits the angiotensin I converting enzyme located preferentially in the endothelium. Therefore, the antihypertensive action of imidapril is mainly attributable to the vasodilation through the inhibitory effects of 6366 A on AT-II synthesis and BK degradation in the vasculature.
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PMID:Effects of the new angiotensin-I-converting enzyme inhibitor imidapril on the responses of isolated vascular preparations to various agonists. 164 67

The chemiluminescence reaction elicited from luminol in the presence of hydroxyl radicals was concentration-dependently suppressed by captopril, indicating efficacious radical scavenging. As to be expected, ACE inhibitors lacking free sulfhydryl groups (ramipril, enalapril) were inactive. However, the endogenous scavenger and anti-oxidant uric acid proved to be far superior to captopril, when concentrations of both were compared that are realized in vivo. A substantial augmentation of endogenous scavenging ability during therapy with captopril thus seems unlikely. In a model of standardized myocardial hypoxia (isolated working heart of the guinea pig with 30 min low flow perfusion) captopril, ramiprilat and uric acid equally improved post-hypoxic heart function. There was no cardioprotective action of captopril in excess of that accountable for by inhibition of ACE. It seems possible that ACE (kininase II) inhibitors exert cardioprotection via elevated tissue levels of kinins: bradykinin also improved heart performance after low flow perfusion and bradykinin-induced coronary dilatation was markedly enhanced in the presence of ramiprilate, reflecting attenuated degradation by endothelial kininase II.
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PMID:[Are the radical scavenging properties of ACE inhibitors with sulfhydryl groups in therapeutically effective concentrations of quantitative significance?]. 165 Aug 63

In addition to angiotensin I converting enzyme (ACE; EC 3.4.15.1) and carboxypeptidase N (CPN; EC 3.4.17.3), other peptidases contribute to bradykinin (BK) degradation in plasma. Rat plasma degraded BK by hydrolysis of the N-terminal Arg1-Pro2 bond, and the characteristics of hydrolysis are consistent with identification of aminopeptidase P (APP; EC 3.4.11.9) as the responsible enzyme. BK and BK[1-5] N-terminal hydrolysis was optimal at neutral pH, was inhibited by 2-mercaptoethanol, dithiothreitol, o-phenanthroline and EDTA, but was unaffected by the aminopeptidase inhibitors amastatin, puromycin and diprotin A, the endopeptidase-24.11 inhibitors phosphoramidon and ZINCOV, and the ACE and CPN inhibitors captopril and D,L-mercapto-methyl-3-guanidinoethylthiopropanoic acid (MERGETPA), respectively. Although kallidin (Lys-BK) was not metabolized directly by APP, conversion to BK by plasma aminopeptidase M (EC 3.4.11.2) resulted in subsequent degradation by APP. BK analogs containing N-terminal Arg1-Pro2 bonds, including [Tyr8-(OMe)] BK and [Phe8 psi(CH2NH)Arg9]BK (B2 agonists), des-Arg9-BK and [D-Phe8]des-Arg9-BK (B1 agonists), and [Leu8]des-Arg9-BK (B1 antagonist), were degraded by APP with Km and Vmax values comparable to those found for BK (Km = 19.7 +/- 2.6 microM; Vmax = 12.1 +/- 1.2 nmol/min/mL). In contrast, B2 antagonists containing D-Arg0 N-termini, including D-Arg[Hyp3,Thi5.8,D-Phe7]BK and D-Arg[Hyp3,D-Phe7,Phe8 psi(CH2NH)Arg9]BK, were resistant to APP-mediated hydrolysis. These data support a role for plasma aminopeptidase P in the degradation of circulating kinins, and a variety of B2 and B1 kinin agonists and antagonists. However, APP does not participate in the degradation of D-Arg0-containing antagonists.
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PMID:Metabolism of bradykinin agonists and antagonists by plasma aminopeptidase P. 165 Oct 78

The relationship between sulfhydryls and cGMP has been observed in several biological processes. Captopril is a sulfhydryl-containing angiotensin converting enzyme (ACE) inhibitor, that decreases PGI2 production in cultured human vascular endothelial cells. Enalapril does not appear to have this property. The role of cyclic GMP (cGMP) and sulfhydryls in the regulatory mechanisms in captopril-induced PGI2 production and Ca++ kinetics was investigated. Bradykinin and Ca ionophore A23187 enhanced PGI2 production, and increased the cytosolic free Ca++ concentration ([Ca++]i). It was observed that 8-bromo cGMP increased intracellular cGMP concentration ([Ca++]i), and decreased PGI2 production without changing [Ca++]i. Sulfhydryl containing compounds such as captopril, N-acetylcysteine and glutathione decreased PGI2 production via increased [cGMP]i. Enalapril, an ACE inhibitor without sulfhydryls, has no effect on PGI2 production, [Ca++]i and [cGMP]i. These results suggested that the presence of sulfhydryl groups is an important factor in the ability of vasoactive substances to induce PGI2 production.
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PMID:Effect of cyclic GMP and sulfhydryl on prostacyclin production by human vascular endothelial cells. 165 36

We have demonstrated previously that a variety of agents including corticosteroids, thyroid hormone, cationophores, methylxanthines, and analogues of cAMP--all of which have diversified functions in various tissues--elevate cellular angiotensin converting enzyme (ACE) activity of bovine endothelial cells in culture. In addition to these agents, we have now found that direct and receptor-mediated stimulators of adenylate cyclase, i.e., forskolin and cholera toxin, increase cellular ACE activity after 48 h incubation in culture. In an attempt to search out a more unifying concept of these stimulatory effects, we have further investigated the roles of second messengers in the stimulatory actions. Ca2+ ionophore A23187 produced significant increases in both intracellular Ca2+ and ACE of endothelial cells. In contrast to Ca2+ ionophore, agents that transiently mobilize Ca2+ from intracellular reserves such as bradykinin, acetylcholine, and ATP have no effect on the level of cellular ACE. Representative agents that elevate cellular cAMP (e.g., isobutyl methylxanthine [IBMX] and dibutyryl cAMP) elevated cellular ACE, but the slightly increased [Ca2+]i produced by these agents did not reach statistical significance. While IBMX, cholera toxin, and forskolin elevated cellular cAMP, other ACE stimulatory agents (hormones and cationophores) had no effect on cAMP. Ca2+ ionophore and the agents that elevated intracellular cAMP potentiated the effect of dexamethasone, thyroid hormone, and aldosterone in elevating cellular ACE activity. Increases in ACE activity produced by all stimulants were inhibited by the presence of 10-50 nM ouabain in the culture medium. Inhibition of ACE elevation by oubain was reversed by increasing the extracellular [K+], thereby implicating Na+, K(+)-ATPase in the ACE regulatory mechanism. These results support the presence of multiple independent mechanisms for the regulation of cellular ACE. In addition to possible involvement of intracellular Ca(2+)- and cAMP-dependent pathways, ACE is also increased by corticosteroids and thyroid hormone through mechanisms unrelated to Ca2+ and cAMP.
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PMID:Involvement of second messenger systems in stimulation of angiotensin converting enzyme of bovine endothelial cells. 165 91


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