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: EC:3.4.16.2 (PCP)
3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Columns containing ribosomes translating poly(U) covalently bound with cellulose (solid-phase translating system) were used to study translocation in ribosomes. It is shown that the passing of elongation factor G (EF-G) with the non-cleavable analog of GTP (GMP-PCP) through a column containing pre-translocated ribosomes results in the increase of competence for puromycin (i. e. to the transition of pre-translocated peptidyl-tRNA into the post-translocated state) just as in the case of the passing of EF-G with GTP. On the other hand, it is shown that the passing of EF-G with GMP-PCP through a column with pre-translocated ribosomes makes them capable of binding the next aminoacyl-tRNA (i. e. leads to the vacation of the ribosomal A-site). Thus, by means of the two independent tests it is shown that EF-G-promoted translocation in the ribosome can proceed without GTP hydrolysis. On the basis of the data obtained, a controlled step-wise elongation of polypeptide with the participation of EF-G without GTP cleavage has been carried out in the solid-phase column system of translation.
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PMID:[Translocation in ribosomes induced by elongation factor G without cleavage of GTP. Study using a solid phase translation system in columns]. 25 70

Phencyclidine (PCP) receptors have been solubilized from rat forebrain membranes with the zwitterionic detergent 3-(3-cholamidopropyl)dimethylammonio-1-propanesulfonate. Specific binding of the potent PCP receptor ligands [3H]thienyl-phencyclidine (TCP) and [3H]MK-801 was restored by incorporating extracted membrane protein into lipid vesicles prepared from a total brain lipid extract. A nearly quantitative recovery of solubilized receptor activity was achieved; this was dependent upon both the concentration of detergent used during membrane solubilization and the concentration of added lipid used during the reconstitution. The single, saturable, binding site measured for both [3H]TCP and [3H]MK-801 in solubilized and reconstituted preparations exhibited properties similar to those of the high affinity PCP binding site labeled by these ligands in brain membranes. The ability of ligands selective for this site (MK-801, TCP, and dexoxadrol) to competitively displace specific [3H]TCP binding was retained after solubilization and reconstitution, although IC50 values measured for these ligands were shifted to higher concentrations. Levoxadrol and haloperidol were ineffective at displacing the radioligand binding in both membrane and vesicle preparations. The additive and dose-dependent ability of glutamate and glycine to enhance [3H]TCP binding to the solubilized/reconstituted receptor further suggests that a direct interaction with the N-methyl-D-aspartate receptor/ion channel complex has been preserved in the vesicle preparations. The photoaffinity labeling of two polypeptides (Mr 98,000 and 59,000) by azido-[3H]PCP was demonstrated in the vesicle preparations; this was largely prevented by competitive displacement of the radioligand with PCP before photolysis. These results establish both an essential lipid dependency and polypeptide composition for the high affinity, haloperidol-insensitive, PCP receptor in brain.
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PMID:High efficiency reconstitution of a phencyclidine/MK-801 receptor binding site solubilized from rat forebrain membranes. 165 3

Constant fragments with different carboxyl terminals, CL(109-211), CL(109-207), and CL-(109-200), were prepared by limited carboxypeptidase P or Y proteolysis of the constant fragment, CL-(109-214), of a type lambda immunoglobulin light chain, and their conformations and stabilities, and formation of the disulfide bond from the reduced fragments, were studied. No change in conformation or stability was observed on removal of three residues from the C-terminal end. Removal of seven or more residues from the C-terminal end destabilized the CL fragment. The rate of disulfide bond formation from reduced CL(109-207) was about 7 times faster than that for CL(109-214). These findings suggest that elongation of the polypeptide chain at least beyond the 207th residue is necessary for folding of the CL fragment into a definite conformation.
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PMID:Conformation and disulfide bond formation of the constant fragment of an immunoglobulin light chain: effect of truncation at the C-terminal region. 190 45

Two highly selective radiolabeled probes for sigma receptors were found to bind with high affinity and capacity to membranes from undifferentiated PC12 cells. [3H]1,3-di-o-tolylguanidine [( 3H]DTG) bound with Kd = 23.7 +/- 4.6 nM and Bmax = 2025 +/- 660 fmol/mg protein. The Kd and Bmax for [3H](+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine ([3H](+)-3-PPP) were 86.3 +/- 21.6 nM and 1539 +/- 242 fmol/mg protein, respectively. These binding parameters were comparable to those observed in guinea pig brain, although the Kd for [3H](+)-3-PPP was 3-fold higher in the PC12 membranes. Both the PC12 and guinea pig brain sites exhibited high affinity for haloperidol, moderate affinity for phencyclidine (PCP), and negligible affinity for MK-801, apomorphine, and (-)-sulpiride. These data suggest a relationship of the PC12 site to sigma receptors. However, all (+)-opiates [+)-benzomorphans and (+)-morphinans) tested bound with markedly lower affinity to the PC12 site compared to guinea pig brain. These include (+)-N-allylnormetazocine [+)-SKF 10,047), (+)-pentazocine, and dextrallorphan. In fact, PC12 sites exhibited preference for (-)-benzomorphans, the reverse stereoselectivity of guinea pig brain sites. Binding of [3H]N-[1-(2-thienyl)cyclohexyl]piperidine [( 3H]TCP) could not be detected, demonstrating absence of PCP receptors on this cell line. Differentiation of cells by treatment with nerve growth factor had no effect on sigma binding parameters. Membranes from guinea pig brain and PC12 cells were photoaffinity-labeled using [3H]azido-di-o-tolylguanidine. In guinea pig brain, a polypeptide of 25 kDa was specifically labeled. However, label was incorporated into polypeptides of 18 kDa and 21 kDa in membranes from PC12 cells. In view of the otherwise similar binding characteristics, the marked differences in affinity for (+)-benzomorphans and molecular weight suggest that PC12 cells contain a molecular form of sigma receptor distinct from that predominant in guinea pig brain. This raises the possibility of multiple sigma receptor types.
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PMID:A sigma-like binding site in rat pheochromocytoma (PC12) cells: decreased affinity for (+)-benzomorphans and lower molecular weight suggest a different sigma receptor form from that of guinea pig brain. 217 17

Two populations of phencyclidine (PCP) binding sites are shown to exist in the rat brain: a high-affinity monovalent ion-sensitive site (Kd of 10-14 nM for [3H]TCP, [3H]N-[1-(2-thienyl)cyclohexyl]piperidine), which exists in both the frontal cortex and the hippocampus, and a lower affinity site (Kd of 80-130 nM for [3H]TCP) which is found in the hippocampus but not in the frontal cortex. The nature of the interactions between the ion-binding sites and the high affinity PCP receptors depend on both ligand structure (PCP or TCP) and the ion involved (K' or Na'). The high-affinity sites are associated with an Mr 90,000 polypeptide whose labeling by [3H]azido phencyclidine is selectively inhibited by monovalent ions.
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PMID:Multiple mode of binding of phencyclidines: high affinity association between phencyclidine receptors in rat brain and a monovalent ion-sensitive polypeptide. 243 96

Binding and photoaffinity labeling experiments were employed in order to differentiate 1-(1-phenylcyclohexyl)piperidine (PCP) receptor sites in rat brain. Two classes of PCP receptors were characterized and localized: one class binds [3H]-N-[1-(2-thienyl)cyclohexyl]piperidine [( 3H]TCP) with high affinity (Kd = 10-15 nM) and the other binds the ligand with a relatively low affinity (Kd = 80-100 nM). The two classes of sites have different patterns of distribution. Forebrain regions are characterized by high-affinity sites (hippocampus greater than frontal cortex greater than thalamus greater than olfactory bulb greater than hypothalamus), but some parts (e.g., hippocampus, hypothalamus) contain low-affinity sites as well. In the cerebellum only low-affinity sites were detected. Binding sites for [3H]PCP and for its photolabile analogue [3H]azido-PCP showed a regional distribution similar to that of the [3H]TCP sites. The neuroleptic drug haloperidol did not block binding to either the high- or the low-affinity [3H]TCP sites, whereas Ca2+ inhibited binding to both. Photoaffinity labeling of the PCP receptors with [3H]AZ-PCP indicated that five specifically labeled polypeptides of these receptors (Mr 90,000, 62,000, 49,000, 40,000, and 33,000) are unevenly distributed in the rat brain. Two of the stereoselectively labeled polypeptides (Mr 90,000 and 33,000) appear to be associated with the high- and low-affinity [3H]TCP-binding sites; the density of the Mr 90,000 polypeptide in various brain regions correlates well with the localization of the high-affinity sites, whereas the density of the Mr 33,000 polypeptide correlates best with the distribution of the low-affinity sites.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Binding studies and photoaffinity labeling identify two classes of phencyclidine receptors in rat brain. 282 87

Photoaffinity labeling of rat brain phencyclidine (PCP) receptors with [3H] azido phencyclidine ([3H]AZ-PCP) reveals the existence of five polypeptides which are specifically labeled by the affinity probe (Mr's 90,000, 62,000, 49,000, 40,000 and 33,000). These labeled components are unevenly distributed in rat brain. In the frontal cortex, thalamus and olfactory bulb, the major bands labeled are the Mr's 90 K and 62 K polypeptides; in the cerebellum most of the labeling is in the 90 K and 33 K bands; and in the hippocampus all but the Mr 40 K band are heavily labeled. Together with dexoxadrol/[3H]PCP competition binding data, which indicated the existence of high and low affinity dexoxadrol/PCP binding sites, these results suggest regional heterogeneity of PCP receptors. The regional distribution of the high affinity dexoxadrol binding sites correlates best with that of the Mr 90 K polypeptide.
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PMID:Regional heterogeneity of rat brain phencyclidine (PCP) receptors revealed by photoaffinity labeling with [3H] azido phencyclidine. 299 36

The role of the "C-terminal tail" segment of long neurotoxins has been investigated. The C-terminal four to five residues of alpha-bungarotoxin and Laticauda colubrina b have been cleaved off by carboxypeptidase P. The effect of such deletion on the toxin conformation has been monitored in proton nuclear magnetic resonance spectra and circular dichroism spectra. The removal of the C-terminal residues primarily affects the chemical shifts of proton resonances of the residues close to the cleavage site and does not induce a major conformational change. Therefore, the C-terminal tail of long neurotoxins does not appear to be important in maintaining the specific polypeptide chain folding. On the other hand, competition binding with tritium-labeled toxin alpha to Narke japonica acetylcholine receptor has revealed that cleavage of the C-terminal residues reduces the binding activity of alpha-bungarotoxin or Laticauda colubrina b to acetylcholine receptor. Thus it is likely that (the basic amino acid residues in) the C-terminal tail is directly involved in the binding of long neurotoxins to electric organ (and muscle) acetylcholine receptor.
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PMID:Role of C-terminal tail of long neurotoxins from snake venoms in molecular conformation and acetylcholine receptor binding: proton nuclear magnetic resonance and competition binding studies. 366 10

The primary structure of a pancreatic stone protein form has been elucidated for the first time. The protein studied was the lowest-Mr form prepared from human pancreatic juice (PSP S1). The N-terminal sequence up to residue 65 had already been determined. The five peptides obtained after staphylococcal protease digestion of the carboxymethylated reduced and succinylated PSP S1 enabled the deduction of the entire sequence. The tryptic peptides arising from the digest of cyclohexanedione--treated PSP S1 and the amino acids released by carboxypeptidase P digestion of PSP S1 confirmed the data of the sequence. The peptides were purified by Sephadex filtration and, if required, by chromatography on DEAE-cellulose or thin-layer cellulose. The amino acid sequences of the peptides were determined with a sequencer. From the sequence data it was deduced that the PSP S1 polypeptide chain contains 133 amino acid residues and has a Mr of 15,000.
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PMID:Complete amino acid sequence of an immunoreactive form of human pancreatic stone protein isolated from pancreatic juice. 366 16

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


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