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 ability of washed whole cells of Treponema denticola ATCC 35405 to hydrolyze (inactivate) substance P, bradykinin, and angiotensin I was studied. Substance P was attacked primarily at the Phe-8-Gly-9 bond by a chymotrypsin-like proteinase (CTLP), at Pro-4-Gln-5 by an endo-acting prolyl oligopeptidase (POPase), and at Gln-5-Gln-6 by an endopeptidase (FALGPA-peptidase). Bradykinin was cleaved at Phe-5-Ser-6 by the FALGPA-peptidase and at Pro-7-Phe-8 by the POPase. Angiotensin I was rapidly converted to angiotensin II by the CTLP, and both angiotensin I and angiotensin II were further hydrolyzed at Pro-7-Phe-8 by the POPase. All these enzymes were assumed to be cell associated and were easily extracted with a mild (0.05 to 0.1%) Triton X-100 treatment. Because it was conceivable that the hydrolysis of substance P at the Phe-8-Gly-9 bond was catalyzed by a CTLP described earlier (V.-J. Uitto, D. Grenier, E. C. S. Chan, and B. C. McBride, Infect. Immun. 56:2717-2722, 1988), the enzyme was purified to homogeneity by means of conventional fast protein liquid chromatography procedures. For kinetic studies, Phe-8(4-nitro)-substance P (NSP) (absorption maximum at 309.2 nm, epsilon = 545 M-1 cm-1) was synthesized to replace substance P as a substrate in kinetic studies. In reversed-phase chromatography, both NSP and substance P gave identical results with both whole cells and the purified enzyme. The CTLP has a mass of 95 kDa, and its activity is suggested to be based on an active seryl residue, on an active imidazole group, and on an active carboxyl group but not on metal cations. The enzyme hydrolyzes N-succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroaniline (SAAPFNA, a typical chymotrypsin substrate) at a high rate and several proteins, such as calf thymus histone, human plasma fibrinogen, milk caseins, and gelatin. Among the substrates tested, substance P showed the highest affinity (Km = 0.22 mM) for the purified enzyme. Depending on conditions, clinically applicable chlorhexidine levels (3.2 mmol/liter, or 0.2%) strongly activated (up to fourfold) the hydrolysis of SAAPFNA by whole cells and the purified CTLP. The hydrolysis of NSP by whole cells and purified CTLP was slightly inhibited by chlorhexidine. The results demonstrated the versatility and the effectiveness of the outer membrane of T. denticola in occasioning a rapid breakdown and inactivation of human bioactive peptides and other peptidolytic catalyses.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Role of the chymotrypsin-like membrane-associated proteinase from Treponema denticola ATCC 35405 in inactivation of bioactive peptides. 754 86

Bradykinin (BK) and its fragments BK(1-8), BK(1-7), and BK(1-5) were incubated with sheep nasal homogenates to investigate the extent of peptide metabolism within the nasal mucosa. The products for both bradykinin and BK(1-8) degradation were found to be BK(1-7) and BK(1-5). BK(1-7) was metabolized to BK(1-5) alone. The patterns of degradation suggest that the Pro7-Phe8 bond of bradykinin was hydrolyzed first, then BK(1-7) was further hydrolyzed to form BK(1-5). The metabolism of bradykinin in rat nasal homogenates and plasma was also investigated. BK(1-5) was the only metabolite measurable in the rat nasal homogenates, likely due to the activity of an endopeptidase. The reduction in the bradykinin degradation rate resulting from the inhibition of angiotensin converting enzyme (ACE) or carboxypeptidase N indicates that these enzymes participate in mucosal bradykinin metabolism to some degree. In comparison, the products of bradykinin hydrolysis in rat plasma were found to be BK(1-8), BK(1-7), and BK(1-5). These results indicate that the enzyme populations or/and activities vary significantly between different species and between different tissues within the same species. Although significant aminopeptidase activities were detected in the sheep nasal homogenates, bradykinin was not affected by their presence, since the N-terminal sequence of bradykinin is not susceptible to hydrolysis by most aminopeptidases.
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PMID:Presystemic bradykinin metabolism in sheep and rat nasal homogenates. 756 26

1. The aim of this study was to analyse the pharmacological characteristics, and second-messenger coupling-mechanisms, of bradykinin B1 receptors in an intact tissue, the rabbit urinary bladder; and to investigate the influence of inhibition of endogenous peptidases on kinin activities. 2. In preparations of rabbit mucosa-free urinary bladder, at 90 min after mounting of the preparations, bradykinin (1 nM-10 microM) evoked contractile responses. In contrast, the B1 receptor-selective agonist [des-Arg9]-BK (10 mM-10 microM) was only weakly active at this time. Contractile responses to [des-Arg9]-BK increased with time of tissue incubation in the organ bath, reaching a maximum after 3 h, when the pD2 estimates were 6.4 +/- 0.3 for bradykinin, and 6.9 +/- 0.2 for [des-Arg9]-BK. 3. Once stabilized, responses to [des-Arg9]-BK in the bladder were competitively antagonized by the B1 receptor-selective antagonists [Leu8,des-Arg9]-BK and D-Arg-[Hyp3,Thi5,D-Tic7,Oic8,des-Arg9]-BK ([des-Arg10]-Hoe140) (pKB estimates were 6.1 +/- 0.1 and 7.1 +/- 0.1, respectively; n = 17-21), but responses were unaffected by the B2 receptor-selective antagonist D-Arg-[Hyp3,Thi5,D-Tic7,Oic8]-BK (Hoe140) (100 nM; n = 4). Contractile responses to bradykinin itself were partially, but significantly, inhibited by the B1 receptor-selective antagonist, [Leu8,des-Arg9]-BK (10 microM) (P < 0.05), or by the B2 receptor-selective antagonist Hoe140 (100 nM) (P < 0.005) alone, and were largely blocked by a combination of the two antagonists (P < 0.0001). 4. The combined presence of the carboxypeptidase inhibitor DL-2-mercaptomethyl-3-guanidinoethylthiopropanoicacid (mergetpa; 10 microM), the neutral endopeptidase inhibitor, phosphoramidon (1 microM),and the angiotensin-converting enzyme inhibitor, enalaprilat (1 microM) increased the potency of bradykinin17 fold (P<0.001), but that of [des-Argl-BK was unchanged (P>0.05): pD2 estimates were 7.6 +/- 0.1 and 6.8 +/- 0.1 for bradykinin and [des-Argl-BK, respectively, in treated preparations. In the presence of peptidase inhibitors, the affinities of the antagonists [Leu8,des-Arg9]-BK and [des-Arg'j-Hoel4O were unchanged as compared with those determined in the absence of peptidase inhibitors (P> 0.05).[Leu8,des-Argj-BK inhibited responses to bradykinin under these conditions (n = 4).5. In endothelium-denuded preparations of the rabbit isolated aorta, an archetypal B1 receptor preparation,contractile responses to the B1 receptor-selective agonist [des-Argl-BK (10nM- 1O0 AM) (and to bradykinin) increased progressively with time of tissue incubation; and [des-Argl-BK responses were completely antagonized by the B. receptor antagonist [Leu8,des-Arg9]-BK (pKB 6.3 +/- 0.2; n = 13).6. In experiments measuring stimulation of hydrolysis of phosphatidylinositol in rabbit urinary bladder,[des-Argl-BK (10 microM- 1 mM), and bradykinin (100 microM) significantly increased accumulation of inositol phosphates (P<0.0001). The increase in accumulation of inositol phosphates evoked by [des-Arg9]-BK(10 microM - 1 mM) was significantly inhibited by [des-Arg'j-Hoe 140 (10 microM) (P <0.01).7. We conclude that in the mucosa-free rabbit urinary bladder, [des-Argl-BK evokes contraction largely via activation of B1 receptors which have similar properties, including time-dependent induction,to B1 receptors in the rabbit isolated aorta. Bradykinin evokes contraction via stimulation of both B1 and B2 receptors, but does not require conversion by peptidases in order to activate B1 receptors. We demonstrate, for the first time, B1 receptor-coupling to phosphatidylinositol hydrolysis in an intact tissue preparation.
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PMID:Bradykinin B1 receptors in the rabbit urinary bladder: induction of responses, smooth muscle contraction, and phosphatidylinositol hydrolysis. 773 87

Interleukin-1 beta (IL-1 beta) induces bronchial hyperresponsiveness (BHR) to bradykinin but not to acetylcholine. We examined whether this was mediated through the inhibition of neutral endopeptidase (NEP) activity and/or through the enhancement of airway microvascular leakage (AML) by IL-1 beta. We administered human recombinant IL-1 beta (500 U) or saline intratracheally and 24 h later measured the airway responses to bradykinin (1 mM; 45 breaths). IL-1 beta-treated rats showed a decrease of 18.5 and 21.1% of NEP activity in the lungs and tracheobronchial tree, respectively (P < 0.05), associated with an augmented response in total lung resistance to bradykinin but with no increase in Evans blue dye extravasation used as a marker of AML. Phosphoramidon (0.1 and 1 mM; 90 breaths), an NEP inhibitor, induced a dose-dependent increase in lung resistance to bradykinin without further enhancing BHR induced by IL-1 beta. Bradykinin-induced AML was not enhanced by phosphoramidon in either saline- or IL-1 beta-treated rats. Similarly, after captopril (1 mM; 90 breaths), an inhibitor of angiotensin-converting enzyme, there was no further enhancement of BHR to bradykinin induced by IL-1 beta. BHR to bradykinin induced by IL-1 beta may result from an inhibition of peptidase activity, such as NEP and angiotensin-converting enzyme, and is not associated with an enhancement of AML.
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PMID:Role of neutral endopeptidase in bronchial hyperresponsiveness to bradykinin induced by IL-1 beta. 777 37

Neutral endopeptidase inhibition (NEP-I) and angiotensin converting enzyme inhibition (ACE-I) act synergistically to produce acute beneficial hemodynamic effects in models of heart failure. Blockade of the formation of angiotensin II (Ang II) acting together with potentiation of the natriuretic peptides, bradykinin and other vasoactive peptides may mediate the interaction of dual enzyme inhibition. In this study, the potential roles of Ang II repression and bradykinin potentiation were evaluated in conscious cardiomyopathic hamsters with compensated heart failure. The Ang II AT1 receptor antagonist, SR 47436 (BMS-186295), was administered at 30 mumol/kg, i.v. followed by i.v. infusion at 1 mumol/kg/min in combination with NEP-I (SQ-28603 at 30 mumol/kg i.v.). Cardiac preload (left ventricular end diastolic pressure) and afterload (left ventricular systolic pressure) decreased significantly more after the combination of Ang II blockade and NEP-I than after either treatment alone. This indicated that repression of Ang II contributes importantly to the NEP-I/ACE-I interaction. Bradykinin B2 receptor antagonism by Hoe 140 at 100 micrograms/kg, i.v. significantly blunted the decrease in left ventricular end diastolic pressure but not the decrease in left ventricular systolic pressure after dual NEP-I/ACE-I (SQ-28603 and enalaprilat each at 30 mumol/kg, i.v.). This suggests that bradykinin potentiation contributes to the preload-reducing, but not the afterload-reducing, acute effects of NEP-I/ACE-I. Hence, both Ang II repression and bradykinin potentiation are factors contributing to the synergistic hemodynamic effects of combined NEP-I and ACE-I in hamsters with heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Repression of angiotensin II and potentiation of bradykinin contribute to the synergistic effects of dual metalloprotease inhibition in heart failure. 785 75

Bradykinin (BK) induces bronchoconstriction in asthmatic but not in normal individuals. Studies in vivo in the human suggest that BK causes cholinergic nerve activation, release of prostanoids, and local axon reflexes with release of tachykinins in the airways. To determine the mechanisms of BK-induced airway narrowing, we investigated the effects of epithelium removal, inhibition of the enzymes neutral endopeptidase (NEP) and cyclooxygenase, and blockade of neural conductance with tetrodotoxin (TTX) on BK-induced responses of human isolated peripheral airways. Responses to BK were recorded from airways with spontaneous intrinsic tone and from airways precontracted with methacholine. Furthermore, we measured the BK-induced release of the prostanoids PGE2, PGI2, and TXA2 from airways with and without epithelium in the absence and presence of indomethacin by radioimmunoassay. Finally, we examined the effect of the bradykinin beta 2 receptor antagonist Hoe 140 and the thromboxane prostanoid (TP) receptor blocking drug GR32191 on BK-induced responses. BK contracted intact and epithelium-denuded airways with spontaneous intrinsic tone, whereas precontracted airways either relaxed or contracted to BK. Removal of the epithelium increased the sensitivity to BK sevenfold without changing the direction of the response. The NEP inhibitor phosphoramidon tended to increase the sensitivity to BK (NS) and did not change the direction of the response. Both contractile and relaxation responses to BK and the release of the prostanoids PGE2, PGI2, and TXA2 by the airway tissues were largely inhibited by indomethacin, whereas TTX had no effect. PGE2, PGI2, and TXA2 were released by both intact and epithelium-denuded airways.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Bradykinin-induced contraction of human peripheral airways mediated by both bradykinin beta 2 and thromboxane prostanoid receptors. 773 35

1. A kinin-inactivating chymotrypsin-like serine-endopeptidase was purified 202-fold from human urine by DEAE-cellulose chromatography, gel filtration, DEAE/HPLC chromatography and affinity chromatography. It hydrolyzed bradykinin at the Phe5-Ser6 peptide bond at a rate of 1.090 mumol min-1 mg protein-1 at pH 8.0 and 37 degrees C. The molecular weight of this endopeptidase H2, estimated by SDS-polyacrylamide gel electrophoresis and by gel filtration, was 60 kDa, and its optimum pH for bradykinin hydrolysis was near 8.5. 2. Bradykinin inactivating activity was inhibited 100% by the serine-proteinase inhibitor PMFS (1 mM) and the chymotrypsin inhibitor TPCK (5 mM). Reagents such as 2-mercaptoethanol (3 mM) and pOH-mercuribenzoate (3 mM) inhibited the enzyme by 100% and 67%, respectively. 3. Endopeptidase H2 hydrolyzes the Phe-Ser bond of peptides related to bradykinin and its activity appears to be limited to peptide chains of < or = 18 amino acid residues since it does not hydrolyze BAM 22, peptide E or kininogen. 4. The molecular size and inhibition profile suggested that endopeptidase H2 differs from the serine-proteinases previously described in rat liver, rat hepatic endothelium, rat and rabbit brain. 5. The physiological role of endopeptidase H2 may be a link between the kinin and neuropeptide systems in the control of water-electrolyte balance.
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PMID:Purification and characterization of endopeptidase H2, a kinin inactivating serine proteinase (kininase) from human urine. 822 Feb 64

To study the effect of maturation on bradykinin-induced airflow obstruction and airway microvascular leakage, we measured changes in both lung resistance (RL) and extravasation of Evans Blue dye in anaesthetized immature (aged 12 +/- 1 days) and adult guinea-pigs (aged 77 +/- 2 days). After measurement of RL after i.v. administration of bradykinin (2.5, 5 and 10 nmol/kg) or vehicle (0.9% NaCl), dye extravasation in the lower airways was examined in the same animal. Bradykinin did not cause a significant increase in RL in immature airways, whereas even 2.5 nmol/kg induced a significant elevation in adult airways. Bradykinin-induced extravasation of Evans Blue dye was greater in adult than in immature animals. Phosphoramidon (2.5 mg/kg), a neutral endopeptidase inhibitor, did not abolish the age-related difference in the amount of dye extravasated, suggesting that mechanisms other than changes in neutral endopeptidase activity may be responsible for the lower potency of bradykinin in inducing airway microvascular leakage in immature airways.
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PMID:Bradykinin is less potent in causing airway microvascular leakage in immature than in adult guinea-pigs. Role of neutral endopeptidase. 835 1

Bradykinin (BK) affects a variety of smooth muscle types, including uterus. These effects are generally short-lived due to metabolism by a variety of enzymes including angiotensin converting enzyme (ACE), endopeptidase 24.11 (EP-24.11) and endopeptidase 24.15 (EP-24.15). The uterotonic action of BK and the limitation of that action by peptidases were examined using isolated rat uterus. BK contracted the estrus, diestrus and day 22 pregnant rat uterus. N-[1(R,S)-carboxy-3-phenylpropyl]-Phe-p-aminobenzoate (10(-7) M), a specific inhibitor of EP-24.11, and N-[1(R,S)-carboxy-3-phenylpropyl]-Ala-Ala-Phe-p-aminobenzoate (10(-6) M), a specific inhibitor of EP-24.15, enhanced BK-induced contraction in the estrus and pregnant uterus. Enalaprilat (6 x 10(-8) M), an inhibitor of ACE, also enhanced BK-induced contraction. The enzyme inhibitors alone did not contract the uterus. Bradykinin B2 receptor antagonism blocked the effects of the inhibitors. ACE is present in the rat uterus, but there are no reports of EP-24.11 or EP-24.15. Here we report that EP-24.11 and EP-24.15 activities are present in the estrus and pregnant rat uterus. Partially purified uterine homogenates metabolized specific model substrates for EP-24.11 and EP-24.15. The enzyme activities were inhibited by N-[1(R,S)-carboxy-3-phenylpropyl]-Phe-p-aminobenzoate and N-[1(R,S)-carboxy-3-phenylpropyl]-Ala-Ala-Phe-p-aminobenzoate, respectively, and increased 5- to 8-fold at term pregnancy as compared to estrus.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Modulatory effect of endopeptidase inhibitors on bradykinin-induced contraction of rat uterus. 839 14

To determine the presence of bradykinin receptors in skeletal muscle, we examined in both displacement and saturation studies the binding of [125I-Tyr8]bradykinin or [3H]bradykinin in three types of skeletal muscle preparations: membrane fractions from guinea pig hindlimb quadriceps, dog semimembranosus and semitendinosus muscles, and L8 rat skeletal muscle myoblasts. Scatchard analysis of [125I-Tyr8]bradykinin x bradykinin competition binding demonstrated specific bradykinin binding of 4.9 and 3.2 fmol/mg protein in dog and guinea pig skeletal muscle preparations, respectively. Unlabeled bradykinin specifically displaced [125I-Tyr8]bradykinin with IC50 values of 36.5 +/- 6 and 118.0 +/- 16.0 pmol/l from dog and guinea pig muscle membranes, respectively. The B2 bradykinin receptor antagonist HOE 140 and the B1 bradykinin receptor antagonist des-Arg9[Leu8]bradykinin displaced the binding of [3H]bradykinin from dog membranes with IC50 values of 0.38 and 217.3 nmol/l, respectively, suggesting that bradykinin binds to a B2-type receptor. In addition, unlabeled bradykinin competed with [3H]bradykinin for binding to dog skeletal muscle membrane preparations in a biphasic manner. To assess whether this represents multiple bradykinin receptor subtypes present in skeletal muscle homogenates or several affinity states of a single binding site, we examined bradykinin receptors on a pure skeletal muscle system, the L8 neonatal rat skeletal muscle myoblast cell line. These myoblasts also contain specific [3H]bradykinin-binding sites with a Bmax of 271 fmol/mg protein and a Kd of 0.83 nmol/l. Competitive agonist binding curves were biphasic (high-affinity IC50 = 3.9 pmol/l, low-affinity IC50 = 22.6 nmol/l) in the absence of guanosine 5'-O-(3-thio-trisphosphate) (GTP gamma S); they shifted to a model of one affinity (8.1 nmol/l) in the presence of GTP gamma S. Because the enzyme neutral endopeptidase 24.11 is an important kininase in skeletal muscle, we examined the effect of the neutral endopeptidase inhibitor phosphoramidon on the binding of bradykinin to dog skeletal muscle membranes. We found that phosphoramidon decreased the apparent Bmax from 7.3 to 5.8 fmol/mg protein. In addition, in this cell line we investigated the action of bradykinin on phosphoinositide hydrolysis. Inositol 1,4,5-trisphosphate (IP3) was measured with a radioreceptor assay. Bradykinin (0.1 nmol/l to 1 mumol/l) induced IP3 formation in a dose-dependent manner (EC50 = 1.42 nmol/l) from a basal level of 72.8 +/- 16 pmol/mg protein to 433 +/- 35.5 at the highest (1 mumol/l) concentration. We conclude that bradykinin B2 receptors are expressed in skeletal muscle. Phosphoinositide hydrolysis upon stimulation of this receptor is an indicator of intracellular signal transduction. Part of the bradykinin binding in skeletal muscle is due to interaction with the enzyme neutral endopeptidase.
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PMID:Bradykinin B2 receptors on skeletal muscle are coupled to inositol 1,4,5-trisphosphate formation. 852 97


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