Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A dipeptidyl aminopeptidase was partially purified from a supernatant fraction of bovine adrenal medulla by gel filtration and anion-exchange chromatography. From gel filtration, the apparent molecular weight of the enzyme was 68,100 and its pH optimum was 9.5. Its Km for hydrolysis of the synthetic substrate arginylarginine-beta-naphthylamide was 5.5 X 10(-6) M. The enzyme was inhibited by metal ion chelating agents and thiol blocking agents, suggesting the requirement for both a metal ion and an active cysteine residue for its activity. Several peptides were cleaved by the dipeptidyl aminopeptidase involving the sequential removal of dipeptides from the N-terminus. Biologically active peptides, such as leucine-enkephalin, methionine-enkephalin, and angiotensin II, were hydrolyzed by the dipeptidyl aminopeptidase although opioid peptides with a length greater than five amino acid residues were not susceptible to hydrolysis. Other peptides with a blocked N-terminus (neurotensin, bombesin) or a proline residue adjacent to a potential cleavage site (substance P) were not hydrolyzed. The ability of this dipeptidyl aminopeptidase to degrade certain neuropeptides suggests that it could be involved in neuropeptide degradation.
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PMID:Characterization of a dipeptidyl aminopeptidase from bovine adrenal medulla. 333 50

Some factors influencing the oxidative activity of upper horizons of spruce forest soils (a mixture of fermentative and humus layers) toward intermediates of the oxidative part of the sulphur cycle were investigated. Preincubation of the soil with added cysteine, sulphide, elemental sulphur or thiosulphate was found to stimulate enzyme systems oxidating any of these compounds. Sulphite and sulphate were ineffective in this respect. The oxidation of elemental sulphur was stimulated by CaCO3, technical urea and high doses of superphosphate and potassium sulphate. It was inhibited by KH2PO4, pure urea, 40 % potassium salt, ammonium nitrate with calcium carbonate and the fertilizer NPK I. It proceeded at the highest rate at approximately 60 % capillary capacity (61 % of mass water content). Oxidation of thiosulphate was stimulated by KH2PO4, pure urea, superphosphate, potassium sulphate and only slightly by the fertilizer NPK I. It was inhibited by CaCO3, 40 % potassium salt and only slightly by ammonium nitrate with calcium carbonate. Potassium chloride, glucose and technical urea were without effect. The oxidation proceeded at the highest rate at 35 % maximal capillary capacity (48 % mass water content).
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PMID:Some factors influencing production of sulphate by oxidation of elemental sulphur and thiosulphate in upper horizons of spruce forest soils. 626 35

A post-proline cleaving enzyme [prolyl endopeptidase, EC 3.4.21.26] was purified about 3,700-fold from an extract of bovine brain by a series of column chromatographies on DEAE-Sephadex, hydroxyapatite and PCMB-T-Sepharose, and gel filtration on Sephadex G-200 using N-carbobenzoxy-Gly-Pro-beta-naphthylamide (Z-Gly-Pro-2-NNap), thyrotropin releasing hormone (TRH) and oxytocin as substrates. The purified enzyme appeared homogeneous as judged by disc gel and SDS gel electrophoreses. The enzyme was most active at pH 7.5 and 7.2 with Z-Gly-Pro-2-NNap and TRH, respectively, and hydrolyzed peptide bonds involving Pro-X (X=amino acid, peptide, ester and amide) bonds of synthetic substrates, oxytocin, vasopressin, neurotensin, substance P, tuftsin, bradykinin, and insulin B chain. However, the enzyme was inert toward collagen, gelatin, and casein. The enzyme was completely inactivated by diisopropylphosphorofluoridate (DFP), Z-Gly-Pro-chloromethyl ketone and p-chloromercuribenzoate (PCMB), while it was not inhibited by phenylmethane sulfonylfluoride (PMSF) or metal chelators. Determination of the amino acid composition revealed that the enzyme contained 25 half-cystines. Modification of three cysteine residues of the enzyme by PCMB led to complete inactivation. The isoelectric point of the enzyme was 4.8, and the molecular weight was estimated to be 76,000 by ultracentrifugal analysis and 75,000-74,000 by both gel filtration and sodium dodecyl sulfate (SDS) gel electrophoresis, suggesting that the enzyme is present as a monomer. These results indicate that the post-proline cleaving enzyme from bovine brain is very similar to those previously purified from lamb brain and kidney in its enzymatic properties, substrate specificity and physicochemical properties, in sharp contrast with the results obtained by Tate, who reported that the bovine brain prolyl endopeptidase was inert toward oxytocin, vasopressin and bradykinin.
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PMID:Post-proline cleaving enzyme (prolyl endopeptidase) from bovine brain. 636 Oct 10

The present study was undertaken to investigate the in vivo effects of nitric oxide (NO) mediating agents injected intracavernosally on penile erection in cats. All NO donors increased the cavernosal pressure and penile length in a dose-dependent manner. The maximal effects on cavernosal pressure and penile length induced by s-nitrosocysteine (NO-CYS) and s-nitroso-n-acetylpenicillamine (SNAP), respectively, were 8-fold and 5-fold increases in pressure, and 45% and 34% increases in length when compared with baseline values. These changes were comparable to that caused by the control drug combination (papaverine, phentolamine and prostaglandin E1). The effects of acetylcholine (ACh) and substance P on cavernosal pressure and penile length were less than those obtained with the control drug combination, NO-CYS (p < 0.01), or SNAP (p < 0.05). N omega-nitro-l-arginine-methyl-ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, significantly decreased the effects of NO-CYS, ACh and substance P on penile erection. This in vivo study with NO donors and an NOS inhibitor suggests that NO is a mediator of penile erection in cats.
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PMID:Nitric oxide mediates penile erection in cats. 750 45

The action of neuropeptides at the synapse is terminated through enzymatic degradation by membrane-bound proteases. We defined and purified membrane-bound proteases functioning at the initial stage of degradation of four neuropeptides. 1. Substance P-degrading endopeptidases isolated from the rat brain and pig striatum showed similar properties to those of endopeptidase-24.16 (neurolysin) except for cleavage sites of substance P. 2. LHRH fragment (1-5)-generating endopeptidases isolated from the neuroblastoma cells and rat brain showed similar properties to those of endopeptidase-24.15 (thimet oligopeptidase). 3. One of two dynorphin-degrading cysteine proteases isolated from neuroblastoma cells showed strict specificity toward the Arg-Arg residues. 4. Endopeptidase-24.11 (neprilysin) isolated from the rat brain was identified as a somatostatin-degrading enzyme.
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PMID:[Membrane-bound proteases involved in neuropeptide degradation in the brain]. 836 28

The influence of Zaprinast (M&B 22948), a guanosine 3',5'-cyclic monophosphate (cGMP)-specific phosphodiesterase inhibitor, was investigated in the pulmonary vascular bed of the cat under conditions of controlled blood flow and constant left atrial pressure. Under baseline conditions, injections of Zaprinast into the perfused lobar artery produced small decreases in lobar arterial pressure without altering systemic arterial or left atrial pressure. When tone was increased with U-46619, Zaprinast caused larger dose-dependent decreases in lobar arterial pressure without altering left atrial pressure. The decreases in lobar arterial pressure were reduced significantly by treatment with the nitric oxide (NO) synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME) or the guanylate cyclase inhibitor methylene blue. Under elevated tone conditions, efferent vagal stimulation and intralobar injections of acetylcholine, substance P, NO solution, and the S-nitrosothiols [S-nitroso-N-acetylpenicillamine (SNAP) and S-nitroso-L-cysteine (CysNO)] decreased lobar arterial pressure in a frequency-dependent and dose-related manner. After treatment with Zaprinast, the decreases in lobar arterial pressure in response to efferent vagal stimulation, the endothelium-dependent vasodilators, and the nitrovasodilators were not changed, whereas the duration of the vasodilator responses as measured by the half times was increased significantly. Vasodilator responses to adenosine, albuterol, and pinacidil were not altered by Zaprinast. These data suggest that cGMP hydrolysis in the lung is rapid and that endothelium-derived NO is important in stimulating basal cGMP production and in regulating vascular tone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Influence of Zaprinast on vascular tone and vasodilator responses in the cat pulmonary vascular bed. 839 Apr 41

A soluble tripeptidylaminopeptidase has been isolated from human post-mortem cerebral cortex by anion exchange, hydrophobic interaction and size-exclusion chromatography. From gel filtration studies the active enzyme can exist in both high molecular weight (M(r) > 10(6) and smaller forms. The enzyme hydrolyses Ala-Ala-Phe-7-amido-4-methylcoumarin with a pH optimum of around 7.5 and Km of 148 microM. It did not hydrolyse N-succinyl-Ala-Ala-Phe-7-amido-4-methylcoumarin, aminoacyl- or dipeptidyl-7-amido-methylcoumarins and was not inhibited by bestatin. The enzyme was inhibited by phenylmethylsulphonyl-fluoride, 3,4-dichloroisocoumarin, N-hydroxymercuriphenyl-sulphonic acid and N-ethylmaleimide showing that its activity is serine and cysteine dependent. The purified enzyme released tripeptides from several naturally occurring neuropeptides with quite broad specificity. Cholecystokinin octapeptide, angiotensin III and neurokinin A were the most rapidly hydrolysed. Peptides with Pro residues around the point of cleavage were not hydrolysed.
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PMID:Purification and characterization of tripeptidylpeptidase-II from post-mortem human brain. 839 12

Substance P (SP) is a neuropeptide that mediates multiple physiological responses including transmission of painful stimuli and inflammation via an interaction with a receptor of known primary sequence. To identify the regions of the SP receptor, also termed the NK-1 receptor, involved in peptide recognition, we are using analogues of SP containing the photoreactive amino acid p-benzoyl-L-phenylalanine (Bpa). In the present study, we used radioiodinated Bpa8-SP to covalently label with high efficiency the rat SP receptor expressed in a transfected mammalian cell line. To identify the amino acid residue that serves as the site of covalent attachment, a membrane preparation of labeled receptor was subjected to partial enzymatic cleavage by trypsin. A major digestion product of 22 kDa was identified. Upon reduction with 2-mercaptoethanol the mass of this product decreased to 14 kDa. The 22-kDa tryptic fragment was purified in excellent yield by preparative SDS/PAGE under nonreducing conditions. Subcleavage with Staphylococcus aureus V8 protease and endoproteinase ArgC yielded fragments of 8.2 and 9.0 kDa, respectively. Upon reductive cleavage, the V8 protease fragment decreased to 3.0 kDa while the endoproteinase ArgC fragment decreased to 3.2 kDa. Taking into consideration enzyme specificity, molecular size, determination of the presence or absence of N-glycosylation sites, and recognition by antibodies to specific sequences of the SP receptor, the V8 protease fragment is Thr-173 to Glu-183, while the endoproteinase ArgC fragment is Val-178 to Arg-190. These two fragments share the common sequence Val-Val-Cys-Met-Ile-Glu (residues 178-183). The site of covalent attachment of radioiodinated Bpa8-SP is thus restricted to a residue within this overlap sequence. The data presented here also establish that the cysteine residue in this sequence Cys-180, which is positioned in the middle of the second extracellular loop, participates in a disulfide bond that links the first and second extracellular loops of the receptor.
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PMID:The peptide binding site of the substance P (NK-1) receptor localized by a photoreactive analogue of substance P: presence of a disulfide bond. 855 54

Substance P (SP) is a peptide neurotransmitter that is involved in multiple responses in both the central and the peripheral nervous systems through a G-protein-coupled contains a number of conserved cysteine residues. To localize and identify the cysteine residues that participate in receptor binding, intact Chinese hamster ovary cells expressing the SP receptor were treated with various sulfhydryl reagents and the effect of these reagents on radioiodinated SP binding affinity and dissociation rate was determined. We used a series of amphiphilic maleimide derivatives in which the reactive maleimide group penetrates to different depths within the plane of membrane. Only the maleimide derivatives with intermediate chain lengths modified receptor binding properties, indicating that the reactive sulfhydryl group is located within a transmembrane domain of the receptor close (within 1.7 nm) to the extracellular border. Since peptide binding to a mutant receptor C199S, in which Cys-199 was replaced by a serine, was found to be insensitive to modulation by sulfhydryl reagents, this reactive sulfhydryl group is on Cys-199 of the receptor. Receptor occupancy by SP protects Cys-199 from modification and thus this residue is either located at or conformationally linked to the SP binding site.
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PMID:Identification of the site in the substance P (NK-1) receptor for modulation of peptide binding by sulfhydryl reagents. 856 43

The nicotinic acetylcholine receptor (AChR) presents two very well differentiated domains for ligand binding that account for different cholinergic properties. In the hydrophilic extracellular region of both alpha subunits there exist the binding sites for agonists such as the neurotransmitter acetylcholine (ACh) and for competitive antagonists such as d-tubocurarine. Agonists trigger the channel opening upon binding while competitive antagonists compete for the former ones and inhibit its pharmacological action. Identification of all residues involved in recognition and binding of agonist and competitive antagonists is a primary objective in order to understand which structural components are related to the physiological function of the AChR. The picture for the localisation of the agonist/competitive antagonist binding sites is now clearer in the light of newer and better experimental evidence. These sites are mainly located on both alpha subunits in a pocket approximately 30-35 A above the surface membrane. Since both alpha subunits are sequentially identical, the observed high and low affinity for agonists on the receptor is conditioned by the interaction of the alpha subunit with the delta or the gamma chain, respectively. This relationship is opposite for curare-related drugs. This molecular interaction takes place probably at the interface formed by the different subunits. The principal component for the agonist/competitive antagonist binding sites involves several aromatic residues, in addition to the cysteine pair at 192-193, in three loops-forming binding domains (loops A-C). Other residues such as the negatively changed aspartates and glutamates (loop D), Thr or Tyr (loop E), and Trp (loop F) from non-alpha subunits were also found to form the complementary component of the agonist/competitive antagonist binding sites. Neurotoxins such as alpha-, kappa-bungarotoxin and several alpha-conotoxins seem to partially overlap with the agonist/competitive antagonist binding sites at multiple point of contacts. The alpha subunits also carry the binding site for certain acetylcholinesterase inhibitors such as eserine and for the neurotransmitter 5-hydroxytryptamine which activate the receptor without interacting with the classical agonist binding sites. The link between specific subunits by means of the binding of ACh molecules might play a pivotal role in the relative shift among receptor subunits. This conformational change would allow for the opening of the intrinsic receptor cation channel transducting the external chemical signal elicited by the agonist into membrane depolarisation. The ion flux activity can be inhibited by non-competitive inhibitors (NCIs). For this kind of drugs, a population of low-affinity binding sites has been found at the lipid-protein interface of the AChR. In addition, several high-affinity binding sites have been found to be located at different rings on the M2 transmembrane domain, namely luminal binding sites. In this regard, the serine ring is the locus for exogenous NCIs such as chlorpromazine, triphenylmethylphosphonium, the local anaesthetic QX-222, phencyclidine, and trifluoromethyliodophenyldiazirine. Trifluoromethyliodophenyldiazirine also binds to the valine ring, which is the postulated site for cembranoids. Additionally, the local anaesthetic meproadifen binding site seems to be located at the outer or extracellular ring. Interestingly, the M2 domain is also the locus for endogenous NCIs such as the neuropeptide substance P and the neurotransmitter 5-hydroxytryptamine. In contrast with this fact, experimental evidence supports the hypothesis for the existence of other NCI high-affinity binding sites located not at the channel lumen but at non-luminal binding domains. (ABSTRACT TRUNCATED)
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PMID:Topology of ligand binding sites on the nicotinic acetylcholine receptor. 940 37


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