Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.4.15.1 (ACE)
18,300 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The testis isozyme of angiotensin-converting enzyme (ACE; EC 3.4.15.1) is a membrane-bound protein that, apart from the first 35 N-terminal residues, is identical to the C-terminal half of somatic ACE and contains the same putative C-terminal membrane anchor. Stable transfection of Chinese hamster ovary (CHO) cells with an expression vector containing the full-length human testis ACE cDNA results in the expression of two forms of recombinant human testis ACE (hTACE): membrane-bound ACE and, surprisingly, large quantities (up to 3 mg/liter) of soluble hTACE in the conditioned medium. Both forms are fully active and are physicochemically similar. However, by phase separation in Triton X-114, the soluble enzyme is hydrophilic, as is an anchor-minus mutant hTACE recovered from the medium of CHO cells transfected with a vector that contains a 3'-truncated testis ACE cDNA lacking the sequence encoding the membrane anchor. In contrast, the membrane-bound hTACE is amphipathic but is converted to a hydrophilic form on treatment with trypsin. The data establish that in ACE the hydrophobic sequence near the C terminus is necessary for membrane anchoring. Moreover, in CHO cells, membrane-bound hTACE is apparently solubilized by proteolytic cleavage of this anchor. A similar mechanism may account for the release of endothelial ACE in vivo to generate serum ACE and more generally for the constitutive processing and solubilization of analogously anchored proteins such as the amyloid precursor protein, among others. The release of membrane-bound ACE in CHO cells may, therefore, provide a useful system for the study of membrane-protein-solubilizing proteases.
...
PMID:Spontaneous solubilization of membrane-bound human testis angiotensin-converting enzyme expressed in Chinese hamster ovary cells. 184 59

Chinese hamster ovary (CHO) cells have been transfected with either a full-length cDNA encoding human angiotensin I-converting enzyme (kininase II; EC 3.4.15.1) (ACE) or a mutated cDNA, in which the last C-terminal 47 amino acids, including the putative transmembrane domain, are not translated. Cell lines expressing high levels of the wild-type ACE or the mutant were established. The cells transfected with the wild-type cDNA (CHO-ACE) express a membrane-bound ectoenzyme with an intracellular C terminus, as shown by indirect immunofluorescence using an antiserum (28A7) raised against a synthetic peptide corresponding to the deduced C terminus of ACE. This enzyme is structurally, immunologically, and enzymatically identical to human kidney ACE. In addition, CHO-ACE cells also produce a secreted form of the enzyme. Neither this secreted form nor the enzyme purified from human plasma is recognized by the antiserum 28A7, indicating that they undergo a truncation in the C-terminal region. On the other hand, the transfected cells expressing the C-terminally truncated mutant (CHO-ACE delta COOH) do not retain ACE in the plasma membrane, but secrete it into the medium. These results indicate that ACE is anchored to the plasma membrane by the predicted C-terminal transmembrane domain, and the secreted form is derived from the membrane-bound form by a post-translational proteolytic cleavage of the C-terminal region.
...
PMID:Expression and characterization of recombinant human angiotensin I-converting enzyme. Evidence for a C-terminal transmembrane anchor and for a proteolytic processing of the secreted recombinant and plasma enzymes. 184 54

Changes in our concepts of angiotensin I converting enzyme are reviewed briefly. The actions of this enzyme go beyond liberating angiotensin II from angiotensin I or inactivating bradykinin. Its very wide distribution in the body and its activity in vitro indicate involvement in the metabolism of other biologically active peptides. The recent molecular cloning of the human enzyme confirmed the existence of a hydrophobic C-terminal peptide that forms the short transmembrane domain of this plasma membrane-bound enzyme. The much longer external portion contains two homologous active site domains but probably only one functional active center. Finally, in spite of the great progress made in studying angiotensin converting enzyme, there are many challenging problems waiting to be solved.
...
PMID:Angiotensin I converting enzyme and the changes in our concepts through the years. Lewis K. Dahl memorial lecture. 217 Feb 73

1. We determined apparent Ki constants of two inhibitors, captopril and CL242,817, for pulmonary endothelial-bound angiotensin converting enzyme (ACE) in anaesthetized rabbits. [3H]-benzoyl-Phe-Ala-Pro was used as the substrate. The apparent kinetic parameters Km and Amax (product of Vmax and microvascular plasma volume) were measured, as was the ratio (Amax/Km) (measured under first order reaction conditions) before and 30s after the i.v. administration of captopril 10 nmol kg-1 or CL242,817, 35 nmol kg-1. 2. Under mixed order reaction conditions, ([S] greater than or equal to Km), apparent Km values increased from 12.2 +/- 1.9 microM to 32.9 +/- 3.3 microM (P less than 0.05) in the captopril-treated rabbits and from 9.3 +/- 2.3 microM to 45.8 +/- 9.8 microM (P less than 0.05) in the CL242,817-treated rabbits, indicative of competitive inhibition. However, apparent Amax values decreased from 10.3 +/- 2.1 to 4.5 +/- 0.8 mumol min-1 (P less than 0.05) and 8.9 +/- 1.7 to 4.8 +/- 0.5 mumol min-1 (P less than 0.05), respectively. 3. Under first order reaction conditions ([S] much less than Km), the Amax/Km ratio decreased from 763 +/- 100 to 125 +/- 38 ml min-1 (P less than 0.05) and 1009 +/- 149 to 126 +/- 44 ml min-1 (P less than 0.05) in the captopril- and CL242,817-treated groups respectively. 4. When the single pass transpulmonary binding of 80pmol [3H]-RAC-X-65 (an ACE inhibitor) was measured in additional rabbits, a significant (P < 0.05) decrease in RAC-X-65 binding was observed 30s after captopril (80% decrease) or CL242,817 (85% decrease), a result expected for a loss of catalytically active enzyme mass due to tightly bound captopril or CL242,817. 5. These results indicate that, in vivo, both captopril and CL242,817 are competitive, tight binding inhibitors of lung ACE. Furthermore, they suggest means for evaluating the interaction of other potential ACE inhibitors with the pulmonary endothelial membrane-bound enzyme, in vivo, possibly in phase I clinical trials.
...
PMID:Inhibition of endothelial-bound angiotensin converting enzyme, in vivo. 228 54

Substance P is a neuropeptide released in vivo from the substantia nigra, the principal substance P nerve terminal region in the rat brain. Its inactivation was investigated in a purified nigral synaptic membrane preparation. The membrane-bound enzyme shares many features with the endopeptidase 24-11 (EC 3.4.24.11): 1) hydrolysis of peptide bonds Gln6-Phe7, Phe7-Phe8 and Gly9-Leu10, 2) sensitivity to the inhibition by phosphoramidon and 3) relative affinity for substance P. Bestatine and captopril inhibit only the hydrolysis of the metabolites. These results suggest that substance P is inactivated in substantia nigra by endopeptidase 24-11 and that a bestatin-sensitive aminopeptidase and angiotensin converting enzyme may play a role in subsequent degradation of the substance P metabolites.
...
PMID:Metalloendopeptidase (EC 3.4.24.11) but not angiotensin converting enzyme is involved in the inactivation of substance P by synaptic membranes of the rat substantia nigra. 247 Oct 29

Ramiprilat is an angiotensin I-converting enzyme (ACE) inhibitor whose particular lipophilicity may modify its inhibitory activity on the cellular form of this enzyme in comparison to ACE inhibitors that are more hydrophilic. The inhibitory activity of ramiprilat on cellular ACE and its binding to plasma membrane ACE have been studied in cultures of pig vascular endothelial cells. ACE activity in pig pulmonary artery endothelial cells is completely inhibited by 100 nM ramiprilat; the IC50 is 2 nM, whatever the form of ACE: soluble ACE released into the culture medium, cellular ACE studied in a cell monolayer homogenate, or tissue ACE purified from pig lung tissue. When added directly to whole living cells in their culture medium, 100 nM ramiprilat inhibits less than 80% of ACE activity in the supernatant while this dose inhibits the cellular form of the enzyme completely, suggesting that ramiprilat reaches and more specifically inhibits membrane-bound ACE rather than ACE secreted by the monolayer of endothelial cells. [3H]ramiprilat binds specifically to the membrane of cultured endothelial cells, in a time and dose-dependent manner (Kd = 6 nM; Bmax = 1,600 fmol/mg of protein); specificity is confirmed by the fact that an anti-ACE antibody prevents binding of [3H]ramiprilat and that both cold ramiprilat as well as other synthetic inhibitor compounds (captopril and enalaprilat) displace [3H]ramiprilat in a dose-dependent manner. Angiotensin I and bradykinin, natural substrates of ACE, do not induce displacement of [3H]ramiprilat bound to the luminal plasma membrane of endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:In vitro interactions between ramiprilat and angiotensin I-converting enzyme in endothelial cells. 248 27

The activities of monoamine oxidase (MAO), catechol-O-methyltransferase (COMT), phenol sulfotransferase (PST), alkaline phosphatase (AP), gamma-glutamyl transpeptidase (GT), and angiotensin converting enzyme (ACE) were quantitated in primary cultures of bovine brain microvessel endothelial cell monolayers and cerebral gray matter. Significant MAO-A and -B, cytosolic and membrane-bound COMT, PST, AP, GT, and ACE activities are demonstrated in bovine gray matter. By comparison, enzyme activities of the monolayers vary with the age of the monolayer and are generally higher in complete monolayers. Relative to gray matter enzyme activities, the monolayers are enriched with AP, GT, and ACE, enzymes considered to be markers for brain endothelium. Results also indicate that the activities of MAO-A and PST in the monolayers approach those found in the gray matter. Conversely, cytosolic COMT and MAO-B activities in the monolayers are negligible and much lower, respectively, compared to activities in gray matter. Additional studies with both tissues suggest that the PST of both tissues is the thermostable form of the enzyme.
...
PMID:Catecholamine-metabolizing enzymes of bovine brain microvessel endothelial cell monolayers. 287 Nov 35

Brain contains a membrane-bound form of endopeptidase-24.15, a metalloendopeptidase predominantly associated with the soluble protein fraction of brain homogenates. Subcellular fractionation of the enzyme in rat brain showed that 20-25% of the total activity is associated with membrane fractions including synaptosomes. Solubilization of the enzyme from synaptosomal membranes required the use of detergents or treatment with trypsin. The specific activity of the enzyme in synaptosomal membranes measured with tertiary-butoxycarbonyl-Phe-Ala-Ala-Phe-p-aminobenzoate as substrate was higher than that of endopeptidase-24.11 ("enkephalinase"), a membrane-bound zinc-metalloendopeptidase believed to function in brain neuropeptide metabolism. Purified synaptosomal membranes converted efficiently dynorphin1-8, alpha- and beta-neoendorphin into leucine enkephalin and methionine-enkephalin-Arg6-Gly7-Leu8 into methionine enkephalin in the presence of captopril, bestatin, and N-[1-(R,S)-carboxy-2-phenylethyl]-Phe-p-aminobenzoate, inhibitors of angiotensin converting enzyme (EC 3.4.15.1), aminopeptidase (EC 3.4.11.2), and membrane-bound metalloendopeptidase (EC 3.4.24.11), respectively. The conversion of enkephalin-containing peptides into enkephalins was virtually completely inhibited by N-[1-(R,S)-carboxy-2-phenylethyl]-Ala-Ala-Phe-p-aminobenzoate, a specific active-site-directed inhibitor of endopeptidase-24.15, indicating that this enzyme was responsible for the observed interconversions. The data indicate that synaptosomal membranes contain enzymes that can potentially generate and degrade both leucine- and methionine-enkephalin.
...
PMID:Synaptosomal membrane-bound form of endopeptidase-24.15 generates Leu-enkephalin from dynorphin1-8, alpha- and beta-neoendorphin, and Met-enkephalin from Met-enkephalin-Arg6-Gly7-Leu8. 287 74

We recently found and partially purified a new membrane-bound metallo dipeptidyl dipeptidase from bovine atrial tissue homogenates (Harris, R.B. & Wilson, I.B. (1984) Arch. Biochem. Biophys. 233, 667-675). We suggested that this enzyme was capable of cleaving the dipeptide, phenylalanyl-arginine from the C-terminus of atriopeptin II to give atriopeptin I. The atriopeptins are two atrial natriuretic peptides and the existence of the atrial peptide system has implicated the mammalian heart as an endocrine organ. The tetrapeptide benzoyl-glycyl-seryl-phenylalanyl-arginine was synthesized because it contains the C-terminal tripeptide sequence of atriopeptin II and should be useful to test the roles of the atrial enzyme and angiotensin I-converting enzyme in processing the atrial peptides. We found that for the atrial enzyme, Vmax was 13-fold higher and Km 7-fold-lower for this stand-in substrate than for benzoyl-glycyl-histidyl-leucine, a standard substrate used to measure converting enzyme activity. The ratio of Vmax/Km as a measure of substrate specificity indicates that the stand-in substrate is 86-fold better than benzoyl-glycyl-histidyl-leucine. In contrast, the stand-in substrate is a 20-fold poorer substrate for the converting enzyme than benzoyl-glycyl-histidyl-leucine. With the stand-in substrate, the converting enzyme showed pronounced substrate inhibition. An effective Vmax and Km were calculated using only concentrations of S below the optimum substrate concentration. These results confirm that the atrial enzyme is distinct from the converting enzyme. They also suggest that the conversion of atriopeptin II to atriopeptin I is a physiological process that is mediated by this enzyme.
...
PMID:Comparison of hydrolysis of atriopeptin II stand-in substrate by atrial dipeptidyl carboxyhydrolase and angiotension I-converting enzyme. 299 58

We are examining the substrate specificity of atrial dipeptidyl carboxyhydrolase, a membrane-bound metallo enzyme that we isolated from bovine atrial tissue homogenates. This enzyme readily removes the dipeptide, Phe-Arg, from Bz-Gly-Ser-Phe-Arg, a stand-in substrate for atriopeptin II, one of several atrial natriuretic factors. We now report that the atrial enzyme cleaves the C-terminal dipeptide, Phe-Arg, from atriopeptin II to form atriopeptin I. The km (pH 7.5) is 25 microM and the ratio of relative Vmax/km as a measure of substrate specificity indicates that atriopeptin II is a 240-fold better substrate than Bz-Gly-His-Leu. Only Phe-Arg was detected as a hydrolysis product, indicating that sequential cleavage of Asn-Ser from atriopeptin II does not occur, and that atriopeptin I is not a substrate. Bz-Gly-Asn-Ser was as good a substrate for the atrial enzyme as Bz-Gly-His-Leu, but Bz-Cys(bzl)-Asn-Ser was not hydrolyzed. This result suggests that the presence of an intact disulfide bond or an S-alkylated residue in the P1 position of a substrate (as in atriopeptin I) prevents hydrolysis by the atrial enzyme. Comparative studies were made with the angiotensin I converting enzyme. Atriopeptin II was not a substrate. The stand-in substrates for atriopeptin I, Bz-Cys(bzl)-Asn-Ser and Bz-Gly-Asn-Ser were barely hydrolyzed, which by itself suggests that atriopeptin I is not a substrate of the angiotensin converting enzyme. Our results strongly suggest that atriopeptin II is converted to atriopeptin I and that hydrolysis is mediated by the atrial enzyme. The angiotensin I converting enzyme plays no role in processing these peptides. We suggest that the atrial enzyme be named atrial peptide convertase.
...
PMID:Conversion of atriopeptin II to atriopeptin I by atrial dipeptidyl carboxy hydrolase. 299 23


<< Previous 1 2 3 4 5 6 7 8 Next >>

---