Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.16.2 (PCP)
 3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human polymorphonuclear neutrophils (PMN) respond to ATP with an elevation in intracellular calcium and a marked enhancement of O2-production in response to stimulation by the chemotactic peptide N'-formyl-Met-Leu-Phe (FMLP). These pertussis toxin-sensitive pathways appear to be mediated by a nucleotide receptor(s) on the surface of human PMN. In the current study, we have examined the binding to intact human PMN of the ATP analog, adenosine 5'-O-(3-thio[35S] triphosphate) [( 35S]ATP gamma S). On the basis of Scatchard analysis, the binding of [35S]ATP gamma S involves at least two sites, one of high and one of low affinity. In the presence of sodium thiophosphate, a compound which did not affect intracellular increases in calcium induced by ATP or N'-formyl-Met-Leu-Phe, a significant fraction of the [35S]ATP gamma S binding was eliminated. This reduction involved both high and low affinity binding of [35S]ATP gamma S and was related to a reduction in numbers of binding sites. The Kd values for the high affinity binding site were unaffected by the presence of sodium thiophosphate, although the low affinity Kd values were numerically increased by 2-fold. In the presence of thiophosphate, [35S]ATP gamma S binding was specific, saturable, and reversible, and was related to a single class of high affinity (Kd = 36 +/- 19 nM) binding sites (184 +/- 144 sites/cell), together with a second class of low affinity (Kd = 1110 +/- 503 nM) binding sites (13,562 +/- 6,851 sites/cells). Competitive binding experiments, based on the ability of nucleotides and ATP analogs to block [35S]ATP gamma S binding to PMN, revealed a rank order of ATP gamma S greater than ATP greater than 2-MeS-ATP = 8-Bromo ATP greater than ADP = ITP greater than AMP-PCP = GTP much greater than CTP. A comparison between the ability of nucleotides to compete with [35S]ATP gamma S binding and their ability to induce a biologic response (elevation of intracellular calcium) revealed a close correlation (r2 = 0.83). These findings support the possibility of a common nucleotide PMN receptor functionally linked to a cellular response which involves increases in intracellular calcium.
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PMID:Adenosine-5'-O-(3-thiotriphosphate) binding to human neutrophils. Evidence for a common nucleotide receptor. 165 77

Scratching induced by intrathecal (IT) administration of kainic acid (0.5 nmol) to rats was inhibited by IT pretreatment with the selective mu agonists levorphanol (30 and 90 nmol), [D-Ala2,N-Met-Phe4,Gly5-ol]-enkephalin (DAGO, 0.4 and 1.1 nmol), or morphine (90 nmol), the mixed mu-delta agonist [D-Ala2,D-Leu5]-enkephalinamide (DADLE, 10 and 30 nmol), or the sigma/phenycyclidine (PCP) agonists dextrorphan (90 nmol) or (+)-N-allyl-N-normetazocine ([+]-NAM, 90 nmol). The kappa agonists dynorphin (1.1 nmol) and ethylketocyclazocine (EKC, 90 nmol) had no significant effect, nor did the selective delta agonist [D-Pen2,D-Pen5]-enkephalinamide (DPDPE, 90 nmol). The nonopioids (+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine ([+]-3-PPP, 90 nmol) and PCP (90 nmol), selective for sigma and PCP sites, respectively, both antagonized kainic-induced scratching. Levorphanol- and DADLE-induced attenuation of scratching was partially antagonized by naltrexone. These findings suggest that opioid inhibition of kainic acid-induced scratching is mediated by classical mu receptors as well as sigma and PCP sites.
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PMID:Opioid inhibition of kainic acid-induced scratching: mediation by mu and sigma but not delta and kappa receptors. 215 73

Glutamine synthetase of plants is the physiological target of tabtoxinine-beta-lactam, a toxin produced by several disease-causing pathovars of Pseudomonas syringae. This toxin, a unique amino acid, is an active site-directed, irreversible inhibitor of glutamine synthetase from pea. ATP is required for inactivation. Neither ADP, AMP, nor adenosine 5'-(beta,gamma-methylene)triphosphate (AMP-PCP) supports inactivation. Adenyl-5'-yl imidophosphate (AMP-PNP) is slowly hydrolyzed by glutamine synthetase to produce adenyl-5'-yl phosphoramidate (AMP-PN) and inorganic phosphate as identified by 31P NMR spectroscopic analysis. AMP-PNP also supports a slow inactivation of glutamine synthetase by tabtoxinine-beta-lactam. These data are consistent with gamma-phosphate transfer being involved in the inactivation. Completely inactivated glutamine synthetase has 0.9 mumol of toxin bound/mumol of subunit. One mumol of ATP is bound per mumol of subunit of glutamine synthetase in the absence of either the toxin or another active site-directed inhibitor, methionine sulfoximine; whereas, a 2nd mumol of either [alpha- or gamma-32P]ATP is bound per mumol of subunit when glutamine synthetase is incubated in the presence of either toxin or methionine sulfoximine until all enzyme activity is lost. These data suggest that the gamma-phosphate hydrolyzed from ATP during inactivation remains with the enzyme-inhibitor complex, as well as the ADP. The open chain form, tabtoxinine, was neither a reversible nor an irreversible inhibitor of glutamine synthetase, suggesting that the beta-lactam ring is necessary for inhibition. The inactivation of glutamine synthetase with tabtoxinine-beta-lactam is pseudo-first-order when done in buffer containing 15% (v/v) ethylene glycol. The rate constant for this reaction is 3 X 10(-2) S-1, and the Ki for the toxin is 1 mM. Removal of the ethylene glycol from the buffer allows the reaction to proceed in a non-first-order manner with the apparent rate constant decreasing with time. As the enzyme is inactivated in these conditions, the binding affinity for the toxin appears to decrease, while the Km observed for glutamate does not change.
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PMID:Inactivation of pea seed glutamine synthetase by the toxin, tabtoxinine-beta-lactam. 287 40

Carboxypeptidase P has been purified by immunoaffinity chromatography from pig kidneys. A single-step assay with Z-Pro-Met (where Z represents benzyloxycarbonyl) as substrate was used, methionine being determined by using L-amino acid oxidase and horseradish peroxidase. The enzyme constitutes about 1.5% of the kidney microvillar proteins. Triton X-100-solubilized and papain-released forms of the enzyme were isolated. The former had an apparent subunit Mr of 135 000, and the latter form contained two polypeptide chains of Mr 128 000 and 95 000. The undenatured forms were dimeric proteins. In common with other microvillar hydrolases, carboxypeptidase P was a glycoprotein and each subunit contained one Zn atom. MnCl2 (1 mM) in the assay was necessary for maximum activity; in its absence, 0.5 mM-ZnSO4 produced a limited activation, but was inhibitory at higher concentrations. The Km for Z-Pro-Met, in the presence of MnCl2, was 4.1 mM, and the kcat. for freshly prepared enzyme was 1230 min-1. The enzyme lost activity during storage at -20 degrees C. In a limited survey of peptides, hydrolysis was observed only with substrates containing a proline, alanine or glycine residue in the P1 position, and these included angiotensins II and III. The best substrate in this series was Val-Ala-Ala-Phe.
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PMID:Proteins of the kidney microvillar membrane. Purification and properties of carboxypeptidase P from pig kidneys. 403 59

The chronic administration of phencyclidine-HCl (PCP-HCl), 10 mg/kg, for 6-7 days resulted in a significant increase in the striatal methionine-enkephalin level, although acute administration induced no change of methionine-enkephalin level in this area. The methionine-enkephalin levels in other areas investigated, i.e. the medulla oblongata/pons, the midbrain, the hypothalamus and the cortex, were unchanged after chronic PCP treatment. These results suggest that chronic administration of PCP alters the enkephalinergic neuronal activity in the striatum.
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PMID:Chronic phencyclidine increases methionine-enkephalin level in mouse striatum. 687 60

The translocation of the mRNA in relation to the ribosome during peptide synthesis represents an example for a mechanochemical reaction in which the chemical bond energy of GTP is transformed into coordinated motion. We demonstrate here that translocation can be explained simply by binding equilibria between the tRNA, the mRNA, and their binding sites on the ribosome. The presence of two cognate tRNAs shifts the association constant for the 70 S ribosome . AUGU3 complex from 6.8 x 10(5) to 2.2 x 10(8) M-1. The elongation factor G and GTP or guanosine-5'-(beta,gamma-methylene)triphosphate GMP-PCP) displace the methionine tRNAs which can be formylated (tRNAfMet) from the quaternary complex 70 S . AUGU3 . tRNAfMet . tRNAPhe. Only the ternary complex Phe-tRNAPhe . elongation factor Tu . GMP-PCP shows an absolute preference for the aminoacyl-tRNA binding site (A site) (K a = 6.6 x 10(6) M-1). AcPhe-tRNAPhe, (N alpha-acetylphenylalanyl-tRNA) an analogue of a peptidyl-tRNA exhibits a 20-fold higher affinity to the peptidyl-tRNA binding site (P site) (K a = 3.5 x 10(6) M-1) as against the A site (K a = 1.8 x 10(6) M-1) at 8 mM Mg2+. Compared to aminoacyl-tRNA and tRNA, peptidyl-tRNA shows a 3- to 15-fold higher affinity toward complementary oligonucleotides both in the binary complex and in the presence of 70 S ribosomes (UUCA . AcPhe-tRNAPhe: K a = 1.9 x 10(5) M-1), UUCA . tRNAPhe:K a = 3.2 x 10(4) M-1). This indicates a stabilization of the peptidyl-tRNA . mRNA complex during translocation. Our data support a concept of mRNA translocation in which the removal of the deacylated tRNA from the P site requires GTP energy and a peptidyl-tRNA . mRNA complex diffuses from its low affinity site (A) to its high affinity binding site (P).
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PMID:Mechanism of translocation. Binding equilibria between the ribosome, mRNA analogues, and cognate tRNAs. 703 57

The effects of acute administration of phencyclidine (PCP) on the steady state levels of methionine-enkephalin in discrete brain areas were investigated in mice. The methionine-enkephalin levels in the medulla oblongata-pons and the midbrain were decreased by the administration of PCP. However, PCP induced no change of the methionine-enkephalin levels in other brain areas at the dose range of 5-20 mg/kg. These results suggest that the pharmacological effects of PCP may involve changes in enkephalinergic neuronal activity.
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PMID:Phencyclidine-induced decrease of methionine-enkephalin levels in mouse brain. 716 Apr 37

Disease-associated proteins separated by two-dimensional electrophoresis (2-DE) are often in the femtomole range. Identification of 2-DE separated proteins by sequencing and amino acid analysis is limited to the lower picomole range. Identification down to the femtomole range can be achieved by matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS). We optimized the measurement by MALDI-MS for the analysis of proteolytic digests of 2-DE-separated proteins. The direct analysis of peptide mixtures can be used for rapid and sensitive protein identification. In some cases, more information about the protein can be obtained by separating the peptides by micro high-performance liquid chromatography (HPLC) before employing MALDI-MS analysis. More peptides are found than in the mixtures, and comparison of HPLC patterns can reveal some differences to be post-translational modifications of proteins, even in the case of identical peptide mass fingerprints. Furthermore, carboxy-terminal sequencing by on-target carboxypeptidase P digestion can be used to confirm the obtained result without the need for more material. The search program FRAGFIT was modified and renamed FRAGMOD to include the modifications of methionine and tryptophan oxidation and alkylation of cysteine by acrylamide into the mass search. By applying this procedure, 15 proteins were identified, among them two different putative phosphorylated forms of two proteins, a putative N-terminal blocking group and four dilated cardiomyopathy-associated proteins. The resulting approach for the identification may be used for large-scale investigations of 2-DE-separated proteins.
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PMID:Identification of human myocardial proteins separated by two-dimensional electrophoresis with matrix-assisted laser desorption/ionization mass spectrometry. 874 Jan 84

The newly approved use of an Atovaquone (Mepron) suspension for treating mild to moderate Pneumocystis carinii (PCP) in patients unable to tolerate trimethoprim-sulfamethoxazole (TMP-SMX), has shown that it is twice as bioavailable compared with the previously licensed tablet formulation. However, Atovaquone use has produced more deaths than TMP-SMX, a problem that may in part be due to its lack of a broad antibacterial spectrum.
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PMID:Atovaquone (Mepron) suspension approved by FDA. Food and Drug Administration. 1136 54

Glaxo Wellcome, makers of atovaquone (Mepron), has announced that the Food and Drug Administration (FDA) has cleared a new suspension formulation of the drug that produces better results than the tablets. The suspension is indicated for the treatment of mild to moderate cases of PCP in patients who are intolerant to other therapies.
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PMID:Liquid atovaquone (Mepron) for PCP. 1136 75


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