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At least 289 records · Page 16Linked to original sources

PubMed2005

Electrophysiological properties of human hypothalamic hamartomas.

The hypothalamic hamartoma (HH) is a rare developmental malformation often characterized by gelastic seizures, which are usually refractory to medical therapy. The mechanisms of epileptogenesis operative in this subcortical lesion are unknown. In this study, we used standard patch-clamp electrophysiological techniques combined with histochemical approaches to study individual cells from human HH tissue immediately after surgical resection. More than 90% of dissociated HH cells were small (6-9 microm soma) and exhibited immunoreactivity to the neuronal marker NeuN, and to glutamic acid decarboxylase, but not to glial fibrillary acidic protein. Under current-clamp, whole-cell recordings in single dissociated cells or in intact HH slices demonstrated typical neuronal responses to depolarizing and hyperpolarizing current injection. In some cases, HH cells exhibited a "sag-like" membrane potential change during membrane hyperpolarization. Interestingly, most HH cells exhibited robust, spontaneous "pacemaker-like" action potential firing. Under voltage-clamp, dissociated HH cells exhibited functional tetrodotoxin (TTX)-sensitive Na(+) and tetraethylammonium-sensitive K(+) currents. Both GABA and glutamate evoked whole-cell currents, with GABA exhibiting a peak current amplitude 10-fold greater than glutamate. These findings suggest that human HH tissues, associated with gelastic seizures, contained predominantly small GABAergic inhibitory neurons that exhibited intrinsic "pacemaker-like" behavior.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1991

Complete structure of the human gene encoding neuron-specific enolase.

At least three genes encode the different isoforms of the glycolytic enzyme enolase. We have isolated the gene for the human gamma- or neuron-specific enolase and determined the nucleotide sequence from upstream to the 5' end to beyond the polyadenylation site. The gene contains 12 exons distributed over 9213 nucleotides. Introns occur at positions identical to those reported for the homologous rat gene, as well as for the human alpha- or nonneuronal enolase gene, supporting the existence of a single ancestor for the members of this gene family. Primer extension analysis indicates that the gene has multiple start sites. The putative promoter region lacks canonical TATA and CAAT boxes, is very G + C-rich, and contains several potential regulatory sequences. Furthermore, an inverted Alu sequence is present approximately 572 nucleotides upstream of the major start site. A comparison of the 5'-flanking region of the human gamma-enolase gene with the same region of the rat gene revealed a high degree of sequence conservation.

Amino Acid Sequence↗

PubMed2003

Crystal structure of Enterococcus hirae enolase at 2.8 A resolution.

We report the crystal structure of an enolase from Enterococcus hirae, which is the first report of a structure determination among gram-positive bacteria. We isolated the enolase gene and determined the base sequence. The amino acid sequence deduced from the DNA sequence suggests that this enolase is composed of 431 amino acids. The amino acid sequence is very similar to those of enolases from eukaryotic and prokaryotic organisms, being 65% and 50% identical to enolases from Escherichia coli and yeast, respectively. The enolase prepared from E. hirae lysate yielded crystals containing one dimer per asymmetric unit. X-ray diffraction patterns were obtained at 2.8 A resolution on a SPring-8 synchrotron radiation source. Crystals belong to space group I4 with unit cell dimensions of a = b = 153.5 A, c = 90.7 A. The E. hirae, yeast, E. coli and lobster enolase structures are very similar. The E. hirae enolase takes an "Open" conformation. The regions in the structure that differ most from other enolases are loops L4 (132-140) and L3 (244-265). Considering the positions of these loops relative to the active site, they seem to have no direct involvement in function. Our findings show that the three dimensional structure of an important enzyme in the glycolytic pathway is evolutionarily conserved among eukaryotes and prokaryotes, including gram-positive bacteria.

Amino Acid Sequence↗

PubMed1994

The hyperthermophilic glycolytic enzyme enolase in the archaeon, Pyrococcus furiosus: comparison with mesophilic enolases.

High enolase activity, as measured by the conversion of 2-phosphoglycerate to phosphoenolpyruvate, was found in the cytoplasm of Pyrococcus furiosus (an anaerobic, hyperthermophilic archaeon that grows optimally at 100 degrees C). In this organism, the enzyme probably functions in a sugar fermentation pathway. The enzyme was purified to homogeneity. It had a temperature optimum of > 90 degrees C and a pH optimum of 8.1. The enzyme was extremely thermostable with a time for 50% inactivation at 100 degrees C of 40 min. In contrast, an enolase from yeast was totally inactivated in 1 min at 88 degrees C. Both the P. furiosus and yeast enzymes required a metal ion for activity, but whereas the yeast enzyme has an absolute requirement for Mg2+, the P. furiosus enolase was equally active in the presence of Mn2+. Both enzymes were competitively inhibited by citrate. P. furiosus enolase, as for mesophilic enolases, probably has a homodimeric structure with subunit M(r) greater than 45,000. A highly conserved sequence of eight amino acids in the N-terminal region was found in enolases from P. furiosus and a wide range of other organisms including bacteria, yeast, birds, and mammals. Substantial differences in the thermal properties of the hyperthermophilic enzyme compared with that from less extreme thermophiles and mesophiles might be due to a substantially enhanced composition of hydrophobic amino acids.

Amino Acid Sequence↗

PubMed1991

Improving the prediction of secondary structure of 'TIM-barrel' enzymes.

The information contained in aligned sets of homologous protein sequences should improve the score of secondary structure prediction. Seven different enzymes having the (beta/alpha)8 or TIM-barrel fold were used to optimize the prediction with regard to this class of enzymes. The alpha-helix, beta-strand and loop propensities of the Garnier-Osguthorpe-Robson method were averaged at aligned residue positions, leading to a significant improvement over the average score obtained from single sequences. The increased accuracy correlates with the average sequence variability of the aligned set. Further improvements were obtained by using the following averaged properties as weights for the averaged state propensities: amphipathic moment and alpha-helix; hydropathy and beta-strand; chain flexibility and loop. The clustering of conserved residues at the C-terminal ends of the beta-strands was used as an additional positive weight for beta-strand propensity and increased the prediction of otherwise unpredicted beta-strands decisively. The automatic weighted prediction method identifies greater than 95% of the secondary structure elements of the set of seven TIM-barrel enzymes.

Amino Acid Sequence↗

PubMed1998

alpha-enolase, a novel strong plasmin(ogen) binding protein on the surface of pathogenic streptococci.

The plasmin(ogen) binding property of group A streptococci is incriminated in tissue invasion processes. We have characterized a novel 45-kDa protein displaying strong plasmin(ogen) binding activity from the streptococcal surface. Based on its biochemical properties, we confirmed the identity of this protein as alpha-enolase, a key glycolytic enzyme. Dose-dependent alpha-enolase activity, immune electron microscopy of whole streptococci using specific antibodies, and the opsonic nature of polyclonal and monoclonal antibodies concluded the presence of this protein on the streptococcal surface. We, henceforth, termed the 45-kDa protein, SEN (streptococcal surface enolase). SEN is found ubiquitously on the surface of most streptococcal groups and serotypes and showed significantly greater plasmin(ogen) binding affinity compared with previously reported streptococcal plasminogen binding proteins. Both the C-terminal lysine residue of SEN and a region N-terminal to it play a critical role in plasminogen binding. Results from competitive plasminogen binding inhibition assays and cross-linking studies with intact streptococci indicate that SEN contributes significantly to the overall streptococcal ability to bind plasmin(ogen). Our findings, showing both the protected protease activity of SEN-bound plasmin and SEN-specific immune responses, provide evidence for an important role of SEN in the disease process and post-streptococcal autoimmune diseases.

Amino Acid Sequence↗

PubMed1995

Chicken alpha-enolase but not beta-enolase has a Src-dependent tyrosine-phosphorylation site: cDNA cloning and nucleotide sequence analysis.

Chicken alpha- and beta-enolase cDNAs have been cloned and analyzed to reveal that alpha- but not beta-enolase has a Src-dependent phosphorylation site. The deduced amino acid sequence of the chicken alpha-enolase showed more than 90% homologies with those of other vertebrate alpha-enolases including amphibian (Xenopus laevis) alpha-like enolase. The chicken beta-enolase, on the other hand, shares 84-85% amino acid sequence homology with mammalian beta-enolases. These chicken enolases also showed more than 70% sequence identity with an insect (Drosophila melanogaster) enolase and around 60% with two yeast enolases. The amino acid sequence between residues 33 and 50 in chicken alpha-enolase coincided with the reported tryptic peptide sequence of rabbit beta-enolase, the tyrosine residue in which was phosphorylated in vitro by Rous-sarcoma-virus tyrosine kinase. The present finding suggested that the tyrosine residue at position 44 in chicken alpha-enolase is the phosphorylation site by the tyrosine kinase. In chicken beta-enolase, on the other hand, the corresponding tyrosine residue was found to be replaced with a histidine residue, in accordance with the previous observation that chicken beta-enolase was not phosphorylated in vivo or in vitro. Northern blot analysis indicated that alpha-enolase mRNA can be expressed in a wide range of chicken tissues, and that the gene expression switch from alpha to beta-enolase occurs just after hatching in developing chicken muscle.

Amino Acid Sequence↗

PubMed1987

Sequence conservation in the 3'-untranslated regions of neurone-specific enolase, lymphokine and protooncogene mRNAs.

The C-terminal protein-coding and the entire 3'-untranslated regions of a cDNA corresponding to human neurone-specific enolase mRNA have been sequenced. The 3'-untranslated region is 892 bases long and shows a high degree of homology with the 3'-untranslated region of rat neurone-specific enolase mRNA. This sequence conservation is not seen in non-neuronal enolase mRNAs. Features of the conserved sequence include an A-rich region approx. 250 bases from the stop codon at a point corresponding to the polyadenylation signal site in non-neuronal enolase mRNA, and a repeating ATTT sequence. This unusual motif in eukaryotic mRNAs has previously been reported in the 3'-untranslated regions of lymphokine and protooncogene mRNAs.

Amino Acid Sequence↗

PubMed1985

Molecular cloning and the nucleotide sequence of cDNA for neuron-specific enolase messenger RNA of rat brain.

The cDNAs to mRNA for rat gamma gamma enolase (neuron-specific enolase; NSE; EC 4.2.1.11) were isolated from a cDNA library by using differential colony hybridization and a hybrid-selected translation assay. By overlapping of the nucleotide sequences of several cDNA inserts, it was found that they spanned 2232 base pairs (bp) which included 1299 bp of the complete coding region, 68 bp of the 5' noncoding region, and 848 bp of the 3' noncoding region, including a polyadenylylation signal. In addition, the poly(A) tail was also found. The amino acid sequence deduced from the nucleotide sequence was composed of 433 amino acids. Southern blot analysis with a cDNA insert detected one hybridizing fragment in rat genomic DNA digested with several different restriction enzymes. Dot-blot and transfer hybridization analyses of poly(A)+ RNA from developing rat brains showed an increase of NSE mRNA 10-30 days after birth.

Amino Acid Sequence↗

PubMed1994

[Biochemical parameters in the comprehensive diagnosis of lung cancer].

Biochemical characteristics of blood serum were studied in 310 patients with lung cancer (stage I-IV), 188 cases of non-malignant pathology od the lung and 35 healthy subjects. Mean levels of total sialic acids, lipid-bound sialic acids, neuron-specific enolase and lactate depydrogenase in blood serum of cancer patients were significantly higher than those in control groups. Mean neuron-specific enolase concentrations in small cell carcinoma of the lung were significantly higher than those in squamous cell and glandular carcinoma and carcinoid. Significant differences were observed for blood serum levels in cases of lung cancer disseminated to the liver and bones, as compared with those without distant metastases. Gamma-glutamyl transferase proced the most sensitive and specific when used for diagnosis of hepatic metastases, while alkaline phospohase--for bone metastases.

Adenocarcinoma↗

PubMed2003

Neuron-specific enolase, nucleotides, nucleosides, purine bases, oxypurines and uric acid concentrations in cerebrospinal fluid of children with meningitis.

To determine the effects of meningitis on cerebral energy metabolism, cerebrospinal fluid concentrations of adenosine monophosphate, inosine monophosphate, inosine, adenosine, guanosine, adenine, guanine, hypoxanthine, xanthine and urate were determined by high-performance liquid chromatography, and neuron-specific enolase by an enzyme immunoassay method, in 100 children with meningitis (45 bacterial, 46 viral and nine tuberculous), aged between 1 month and 13 years, and in 160 age-matched controls. Compared with controls, patients with bacterial meningitis showed high concentrations of hypoxanthine, xanthine and urate; patients with viral meningitis showed high concentrations of inosine, guanosine, xanthine, urate and neuron-specific enolase; and patients with tuberculous meningitis showed very high concentrations of inosine, xanthine and urate. Xanthine and urate concentrations were significantly higher in patients with tuberculous meningitis than in patients with viral or bacterial meningitis. These results suggest that in the acute stage of bacterial, viral and tuberculous meningitis, neuronal energy metabolism may be altered. The measurement of cerebrospinal xanthine and uric acid concentrations may be useful for the early diagnosis of a tuberculous origin.

Child↗

PubMed1992

Activation of protein kinase C by the 14-3-3 proteins homologous with Exo1 protein that stimulates calcium-dependent exocytosis.

The 14-3-3 proteins are a family of acidic proteins found mainly in the brain and are suggested to have a role in monoamine synthesis based on their ability to activate tyrosine and tryptophan hydroxylases in the presence of type II Ca2+/calmodulin-dependent protein kinase. Recently, however, it has been demonstrated that a member of the 14-3-3 family, termed Exo1, stimulates Ca(2+)-dependent exocytosis in permeabilized adrenal chromaffin cells, suggesting that this protein family may influence the protein kinase C-mediated control of Ca(2+)-dependent exocytosis. Here we show that the 14-3-3 proteins activate protein kinase C at about 2-fold more than the known level of the activated protein kinase, i.e. the activity of protein kinase C in the presence of Ca2+ and phospholipids. This raises the possibility that the cellular activity of protein kinase C is regulated by diverse members of the 14-3-3 family and that the reported ability of Exo1 to reactivate Ca(2+)-dependent exocytosis is based on its stimulatory effect on protein kinase C activity. The 14-3-3 family, therefore, appears to be a multifunctional regulator of cell signalling processes mediated by two types of Ca(2+)-dependent protein kinase, protein kinase C and type II calmodulin-dependent protein kinase.

14-3-3 Proteins↗

PubMed1993

Molecular cloning and characterization of the Candida albicans enolase gene.

A DNA clone containing the putative Candida albicans enolase gene (ENO1) was isolated from a genomic DNA library. The sequenced insert contained a continuous open reading frame of 1,320 bp. The predicted 440-amino-acid protein is 78 and 76% identical, respectively, to Saccharomyces cerevisiae enolase proteins 1 and 2. Only one enolase gene could be detected in C. albicans genomic DNA by Southern analysis with a homologous probe. Northern (RNA) analysis detected a single, abundant C. albicans ENO1 transcript of approximately 1,600 nucleotides. When cells were grown on glucose, levels of ENO1 mRNA were markedly increased by comparison with ENO1 mRNA levels in cells grown on ethanol, a gluconeogenic carbon source. In contrast to this glucose-mediated transcriptional induction, the carbon source had no dramatic effect on the levels of enolase protein or enzyme activity in the C. albicans strains tested. These results suggest that posttranscriptional mechanisms are responsible for modulating expression of the C. albicans enolase gene.

Amino Acid Sequence↗

PubMed1991

Molecular structure of the human muscle-specific enolase gene (ENO3).

The single human gene for muscle-specific enolase was isolated and its structure was characterized, from which the mature mRNA transcript and encoded protein were also deduced. The gene contains 12 exons, spans approx. 6 kb and encodes a protein of 433 residues. The gene structure is similar to that found for the rat neuron-specific enolase gene, and the deduced protein aligns precisely with other enolase sequences, including the sequence of the only published crystallized enolase, yeast eno-1. The 5' boundary of the gene includes a 5' non-coding exon and is characterized by an upstream TATA-like box and CpG-rich region. This region contains potential recognition motifs for general transcriptional regulation involving Sp1, activator protein 1 and 2, CCAAT box transcription factor/nuclear factor I and cyclic AMP, and for muscle-specific transcriptional regulation involving a CC(A + T-rich)6GG box, M-CAT-box CAATCCT and two myocyte-specific enhancer-binding factor 1 boxes.

Amino Acid Sequence↗

PubMed2004

cDNA cloning and characterization of enolase from Chinese cabbage, Brassica campestris ssp. Pekinensis.

An enolase-encoding cDNA clone from Chinese cabbage, Brassica campestris ssp. Pekinensis, was isolated. This gene (Accession number: AY307448) had a total length of 1580bp with an open reading frame of 1335bp, and encoded a predicted polypeptide of 444 amino acids with a molecular weight of 47.38 kDa. The deduced amino acid (aa) sequence shared identity with a number of enolases ranging from Bacillus subtilis to human beings and had much higher identity with other plant enolases than with enolases from Bacillus, yeast and human beings. Comparison of its primary structure with those of other enolases revealed the presence of an insertion of 5 amino acids in enolase of Chinese cabbage. Expression of the cloned enolase gene decreased under salt stress, but increased in response to low temperature. Southern blot analysis of genomic DNA indicated that low-copies of enolase gene were present in the genome of Chinese cabbage.

Amino Acid Sequence↗

PubMed1991

Plant enolase: gene structure, expression, and evolution.

Enolase genes were cloned from tomato and Arabidopsis. Comparison of their primary structures with other enolases revealed a remarkable degree of conservation, except for the presence of an insertion of 5 amino acids unique to plant enolases. Expression of the enolase genes was studied under various conditions. Under normal growth conditions, steady-state messenger and enzyme activity levels were significantly higher in roots than in green tissue. Large inductions of mRNA, accompanied by a moderate increase in enzyme activity, were obtained by an artificial ripening treatment in tomato fruits. However, there was little effect of anaerobiosis on the abundance of enolase messenger. In heat shock conditions, no induction of enolase mRNA was observed. We also present evidence that, at least in Arabidopsis, the hypothesis that there exists a complete set of glycolytic enzymes in the chloroplast is not valid, and we propose instead the occurrence of a substrate shuttle in Arabidopsis chloroplasts for termination of the glycolytic cycle.

Amino Acid Sequence↗

PubMed1995

Posttranscriptional and posttranslational control of enolase expression in the facultative Crassulacean acid metabolism plant Mesembryanthemum Crystallinum L.

During the induction of Crassulacean acid and metabolism by environmental stresses in the common ice plant (Mesembryanthemum crystallinum L.), enzyme activities involved in glycolysis and gluconeogenesis, including enolase (2-phospho-D-glycerate hydrolase), increase significantly. In this study, we describe two nearly identical cDNA clones (Pgh1a and Pgh1b) encoding enolase from the common ice plant. This cytoplasmically localized enzyme is encoded by a gene family of at least two members. The polypeptides encoded by these cDNAs share a high degree of amino acid sequence identity (86.7-88.3%) with other higher plant enolases. Enolase activity increased more than 4-fold in leaves during salt stress. This increase was accompanied by a dramatic increase in Pgh1 transcription rate and the accumulation of enolase transcripts in leaves. Pgh1 transcript levels also increased in leaves in response to low temperature, drought, and anaerobic stress conditions and upon treatment of unstressed plants with the plant growth regulators abscisic acid and 6-benzylaminopurine. In roots, enolase transcripts increased in abundance in response to salt, low and high temperature, and anaerobic stresses. Surprisingly, we observed no increase in enolase protein levels, despite the increased levels of mRNA and enzyme activity during salt stress. The stress-induced increase in enolase activity is therefore due to posttranslational regulation of steady-state enzyme pools. Our results demonstrate that the stress-induced shift to Crassulacean acid metabolism in the ice plant involves complex regulatory control mechanisms that operate at the transcriptional, posttranscriptional, and postranslational levels.

Amino Acid Sequence↗

PubMed1985

Malignant teratoma in the brain. An immunohistochemical study.

A case of intracranial malignant teratoma found in a 27-year-old man was reported. This unique tumor was found in the right frontal lobe separated from the pineal region and revealed various tissue components such as stratified squamous epithelium, glandular tissues, neuron, glia, ependyma, fibromuscular tissue, cartilage, bone, hemangiomatous lesion, melanin-laden cells, and some germ cell components. An immunohistochemical study demonstrated the presence of S-100 protein, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), carcinoembryonic antigen (CEA), and Factor VIII in some tumourous components. In particular, the distribution of S-100 protein in some germ cells suggested the possibility of the neuroectodermal origin of the germ cells or, alternatively, differentiation to the neuroectoderm.

Adult↗