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

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Query: UNIPROT:P01189 (beta-endorphin)
21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proline endopeptidase (E.C.3.4.21.26) is an enzyme which cleaves several neuropeptides at the carboxyl-side of proline residues. Some peptide substrates of this enzyme may be found in the rat hypothalamus (thyrotropin releasing hormone, neurotensin, substance P, oxytocin, vasopressin, beta-endorphin). Recent research has shown that the hypothalamic levels of some of these substances (e.g., vasopressin, beta-endorphin) change by a variety of training procedures. We studied the effect of various forms of training on the activity of proline endopeptidase of rat hypothalamus. The present results show that the activity of this enzyme is not altered by electroconvulsive shock or inhibitory avoidance training when measured, 0, 1, or 3 hr after these procedures. Other behavioral procedures (habituation to an open field, two-way active avoidance conditioning, or 1 min of inescapable footshock) also had no effect on hypothalamic proline endopeptidase activity measured immediately after training or test sessions. We conclude that proline endopeptidase probably does not play a regulatory role in the effect of synaptically released hypothalamic neuropeptides on behavior.
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PMID:Hypothalamic proline endopeptidase activity is not changed by various behavioral procedures. 353 16

Previous studies have shown that three distinct enzymes, amastatin-sensitive aminopeptidase, captopril-sensitive peptidyl dipeptidase A, and phosphoramidon-sensitive endopeptidase-24.11, played a critical role in the inactivation of enkephalins in isolated preparations. In the present study, therefore, the rank order of the potency of three endogenous opioid peptides, [Met5]-enkephalin, [Leu5]-enkephalin, and beta-endorphin, in three isolated preparations, guinea-pig ileum, mouse vas deferens, and rat vas deferens, was estimated in the presence of the mixture of three peptidase inhibitors, amastatin, captopril, and phosphoramidon. [Met5]-Enkephalin was approximately three-fold more potent than [Leu5]-enkephalin and four-fold more potent than beta-endorphin in guinea-pig ileum in which three opioid peptides were indicated to act on mu-receptors. Additionally, [Met5]-enkephalin was slightly but significantly more potent than [Leu5]-enkephalin and approximately twenty-fold more potent than beta-endorphin at delta-receptor sites in mouse vas deferens. Moreover, [Met5]-enkephalin was approximately three-fold more potent than [Leu5]-enkephalin, but sixty-fold less potent than beta-endorphin in rat vas deferens in which the opioid-receptor type interacting with enkephalins could not be determined. In conclusion, the well-known rank order of the potency of three endogenous opioid peptides was shown to be altered in both guinea-pig ileum and mouse vas deferens but not in rat vas deferens by the pretreatment of the preparations with the mixture of three peptidase inhibitors.
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PMID:The relative potency of enkephalins and beta-endorphin in guinea-pig ileum, mouse vas deferens and rat vas deferens after the administration of peptidase inhibitors. 376 46

gamma-Endorphin generating endopeptidase (gamma EGE) activity is an enzyme activity which converts beta-endorphin into gamma-endorphin and beta-endorphin-(18-31). The inhibitory potency on gamma EGE activity of neuropeptides and analogues or fragments of neuropeptides was tested. Dynorphin-(1-13) (IC50: 0.14 microM), human beta-endorphin-(1-31) (IC50: 15.5 microM), porcine ACTH-(1-39) (IC50: 6.3 microM), and substance P (IC50: 26 microM) had an inhibitory activity on gamma EGE activity. beta-Endorphin-(18-31) (IC50: 0.35 microM) but not gamma-endorphin potently inhibited gamma EGE activity. The IC50 of poly (Lys)40-60 was 0.8 microM. It is concluded that 1) gamma EGE activity is strongly inhibited by its product beta-endorphin-(18-31), 2) the enzyme is strongly inhibited by peptides with an aromatic amino acid at the NH2-terminal and/or basic amino acids in the COOH-terminal of the peptide chain.
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PMID:Inhibition of gamma-endorphin generating endopeptidase activity of rat brain by peptides: structure activity relationship. 391 46

gamma-Endorphin is a naturally occurring biologically active peptide that is produced by an endopeptidase activity cleaving its precursor beta-endorphin. This enzyme was termed gamma-endorphin generating enzyme (gamma-EGE). In order to quantitate gamma-EGE activity by means of a simple and sensitive assay two synthetic peptides derived from the sequence surrounding the gamma-EGE cleavage site in beta-endorphin were tested as substrates. One of these peptides Ac-Val-Thr-Leu-Phe-Lys-NHCH3 fulfilled all criteria for a suitable gamma-EGE substrate. The peptide was exclusively cleaved at the correct bond for gamma-EGE upon incubation with brain synaptic membranes, and this cleavage was inhibited by the naturally occurring substrate beta-endorphin. The peptide was insensitive to cleavage by exopeptidases and cathepsin D. Addition of a 14C-labeled methyl group at the lysine residue of this peptide by reductive methylation did not alter its properties as a substrate for gamma-EGE activity. The use of the 14C-labeled peptide allowed sensitive quantitation of its radioactive products after simple separation by hydrophobic chromatography on minicolumns containing polystyrene beads. gamma-EGE activity increased linearly with a protein concentration and incubation time. This assay can be used for reliable quantitation of gamma-EGE activity and permits investigations on the regulation of gamma-endorphin production.
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PMID:Quantitation of the endopeptidase activity generating gamma-endorphin from beta-endorphin in rat brain synaptic membranes by a radiometric assay. 620 8

The biotransformation of adrenocorticotropin (ACTH-(1-39)) by brain synaptic membranes has been studied. Peptide fragments of ACTH-(1-39) which were formed during in vitro incubation of the peptide with membrane preparations were isolated by high pressure liquid chromatography and characterized by determination of amino acid composition and NH2- terminal residue. At pH 7.4, ACTH-(1-38) was found as the main metabolite, together with ACTH-(7-21) and ACTH-(7-20). In addition, a series of secondary products was identified. At pH 6.2, ACTH-(1-38), ACTH-(1-37), and ACTH-(1-36) were exclusively formed, while at pH 8.5, ACTH-(1-39) was converted into ACTH-(1-16), ACTH-(17-39), ACTH-(22-39), and ACTH-(3-15). Time course experiments demonstrated the action of a carboxypeptidase activity and a trypsin-like endopeptidase on ACTH-(1-39) as predominant proteolytic events. The carboxypeptidase was optimally active at pH values of 5.7 or below. These enzymes play an essential role in the stepwise conversion of ACTH-(1-39) in brain. It is suggested that they are involved in the modulation of the central activities of ACTH fragments in the brain.
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PMID:Proteolysis of adrenocorticotropin in brain. Characterization of cleavage sites by peptidases in synaptic membranes and formation of peptide fragments. 630 63

The primary mechanism of activation of intracellular prohormones seems to involve proteolytic cleavage at sequences of consecutive basic residues. Thus, all the known biologically active peptides derived from the prohormone of corticotropin and beta-endorphin appear to be excised initially by enzymes with this specificity. The C-terminal peptide, beta-endorphin (1-31), is generated by cleavage at a lysyl arginine sequence and an additional cleavage can give rise to the related peptides, beta-endorphin (1-27) and beta-endorphin (1-26). These derivatives of beta-endorphin are released by an endopeptidase that appears to catalyse cleavage on the carboxyl side of paired lysine residues, followed by the action of a carboxypeptidase B-like enzyme (Fig. 1). The beta-endorphin fragments, beta-endorphin (1-27) and beta-endorphin (1-26), have been isolated from porcine and bovine pituitary but the C-terminal dipeptide, glycyl glutamine, has not been reported previously. Here we describe the isolation of glycyl glutamine from porcine pituitary and present evidence for its presence in sheep brain stem. When applied ionophoretically to brain stem neurones in the rat, the dipeptide exhibited an inhibitory action on cell firing.
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PMID:Glycyl glutamine, an inhibitory neuropeptide derived from beta-endorphin. 631 48

The kinetics of the reactions of nine opioid peptides with the neutral endopeptidase ("enkephalinase") activities of human kidney, rat kidney, and rat brain have been determined. These opioid peptides can be divided into two classes, those that are good inhibitors of Leu5-enkephalin hydrolysis (Ki less than 75 microM) and good substrates for the enzyme, and those that are poor inhibitors (Ki greater than 500 microM) and are not substrates for the enzyme. The former group includes Leu5-enkephalin, Met5-enkephalin, Met5-enkephalin-Arg6-Phe7, beta-lipotropin, and gamma-endorphin, while the nonreactive opioid peptides include alpha-neo-endorphin, beta-neo-endorphin, dynorphin, and beta-endorphin. These results suggest that those peptides containing the Met5-enkephalin sequence are more reactive than those containing the Leu5-enkephalin sequence. The lack of specificity of this neutral endopeptidase indicates that it may function in the degradation of a variety of biologically active peptides.
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PMID:Reaction of opioid peptides with neutral endopeptidase ("enkephalinase"). 637 10

N alpha-Acyl amino acid releasing enzyme (NAARE), an enzyme cleaving acetylMet-Ala at the Met-Ala bond was purified from rat brain cytosol to apparent homogeneity by salt precipitation, gel filtration, and several steps of ion exchange. Levels of NAARE exceeded acylase measured with acetylmethionine in all brain regions and subcellular fractions examined: 60% was associated with cytosol and the remainder with debris or the crude nuclear and mitochondrial-synaptosomal subfractions. Activity was highest in pituitary and was approximately 0.5-0.6 that of liver or kidney. The purified enzyme preferentially hydrolyzed acetylmethionyl peptides: Km for acetylMet-Ala was 0.93; Vmax, 3.5 nmol-1 (kcat, 1185) with pH optimum of 8.9 as compared with 8.2 for acylases measured in cytosol. The purified enzyme was devoid of acylase and common exo- and endopeptidase contamination. Structure-activity relationships examined with synthetic formylated or acetylated peptides indicated no significant effects for di- or tripeptides if the second substituent was Ala, Ser, Asn, or Thr, but the activity was reduced 0.5-fold for Leu, a branched-chain amino acid. No hydrolysis was observed for polypeptides with five or more residues having N-terminal acetylated Tyr (enkephalin) or Ser (alpha-melanocyte-stimulating hormone, thymosin alpha 1), supporting the notion that the enzyme plays a role only in turnover of smaller peptides formed perhaps as a result of endopeptidase cleavage of proteins or polypeptides containing acetylated Met at the N terminus.
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PMID:Observations on N alpha-deacetylation of model amino acids and peptides: distribution and purification of a specific N-acyl amino acid releasing enzyme in rat brain. 686 20

A porcine kidney microsomal metalloendopeptidase has been enriched 3900-fold. Gel filtration on a calibrated Toyo-Soda G-3000 SW column indicated an appropriate molecular weight for the endopeptidase of 88,000 +/- 2000. The purified enzyme is inhibited by a number of synthetic inhibitors of thermolysin. The endopeptidase hydrolyzes the succinyl (Suc)-containing fluorogenic peptide substrate Suc-Ala-Ala-Phe-(7-amino-4-methylcoumarin) at the Ala-Phe position with a Km of 2.9 X 10(-4) M. The endopeptidase also hydrolyzes a variety of peptides including corticotropin, substance P, angiotensin I and II, neurotensin, somatostatin, bradykinin, and the renin tetradecapeptide substrate. The endopeptidase hydrolyzes both [Leu]- and [Met]enkephalin at the Gly-Phe bond.
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PMID:Purification of a membrane-bound metalloendopeptidase from porcine kidney that degrades peptide hormones. 703 58

One case of breast neuroendocrine primary small cell carcinoma with light microscopic and immunohistochemical findings is reported. The patient died of unrelated disease 21 months after diagnosis and treatment by modified radical mastectomy, radiotherapy and subsequent chemotherapy. Immunohistochemical studies revealed cytokeratin and neuroendocrine markers (chromogranin, neuron-specific enolase) immunostaining on tumoral cells. Expression for neuropeptides (met-enkephalin, leu-enkephalin, beta-endorphin) and CALLA antigen was found. Based on this case report and six other previously reported cases, breast neuroendocrine primary small cell carcinoma appears to be a very aggressive tumor for which no firm conclusions regarding treatment can be drawn.
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PMID:Neuroendocrine primary small cell carcinoma of the breast. Report of a case and review of the literature. 863 51


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