References of "Biochimica et Biophysica Acta - General Subjects"
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See detailDer p 1 is the primary activator of Der p 3, Der p 6 and Der p 9 the proteolytic allergens produced by the house dust mite Dermatophagoides pteronyssinus
Herman, Julie ULg; Thelen, Nicolas ULg; Smargiasso, Nicolas ULg et al

in Biochimica et Biophysica Acta - General Subjects (2013), 1840

Background: The enzymatic activity of the four proteases found in the house dust mite Dermatophagoides pteronyssinus is involved in the pathogenesis of allergy. Our aim was to elucidate the activation ... [more ▼]

Background: The enzymatic activity of the four proteases found in the house dust mite Dermatophagoides pteronyssinus is involved in the pathogenesis of allergy. Our aim was to elucidate the activation cascade of their corresponding precursor forms and particularly to highlight the interconnection between proteases during this cascade. Methods: The cleavage of the four peptides corresponding to the mite zymogen activation sites was studied on the basis of the Förster Resonance Energy Transfermethod. The proDer p 6 zymogen was then produced in Pichia pastoris to elucidate its activation mechanismbymite proteases, especially Der p 1. The role of the propeptide in the inhibition of the enzymatic activity of Der p 6 was also examined. Finally, the Der p 1 and Der p 6 proteases were localised via immunolocalisation in D. pteronyssinus. Results: All peptides were specifically cleaved by Der p 1, such as proDer p 6. The propeptide of proDer p 6 inhibited the proteolytic activity of Der p 6, but once cleaved, it was degraded by the protease. The Der p 1 and Der p 6 proteases were both localised to the midgut of the mite. Conclusions: Der p 1 in either its recombinant formor in the natural context of house dustmite extracts specifically cleaves all zymogens, thus establishing its role as a major activator of both mite cysteine and serine proteases. General significance: This finding suggests that Der p 1 may be valuable target against mites. [less ▲]

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See detailStructural Determinants of Specificity and Catalytic Mechanism in mammalian 25-kDa Thiamine Triphosphatase
Delvaux, David; Kerff, Frédéric ULg; Murty, Mamidanna R.V.S. et al

in Biochimica et Biophysica Acta - General Subjects (2013), 1830

Background: Thiamine triphosphate (ThTP) is present in most organisms and might be involved in intracellular signaling. In mammalian cells, the cytosolic ThTP level is controlled by a specific thiamine ... [more ▼]

Background: Thiamine triphosphate (ThTP) is present in most organisms and might be involved in intracellular signaling. In mammalian cells, the cytosolic ThTP level is controlled by a specific thiamine triphosphatase (ThTPase), belonging to the CYTH superfamily of proteins. CYTH proteins are present in all superkingdoms of life and act on various triphosphorylated substrates. Methods: Using crystallography, mass spectrometry and mutational analysis, we identified the key structural determinants of the high specificity and catalytic efficiency of mammalian ThTPase. Results: Triphosphate binding requires three conserved arginines while the catalytic mechanism relies on an unusual lysine-tyrosine dyad. By docking of the ThTP molecule in the active site, we found that Trp-53 should interact with the thiazole part of the substrate molecule, thus playing a key role in substrate recognition and specificity. Sea anemone and zebrafish CYTH proteins, which retain the corresponding Trp residue, are also specific ThTPases. Surprisingly, the whole chromosome region containing the ThTPase gene is lost in birds. Conclusion: The specificity for ThTP is linked to a stacking interaction between the thiazole heterocycle of thiamine and a tryptophan residue. The latter likely plays a key role in the secondary acquisition of ThTPase activity in early metazoan CYTH enzymes, in the lineage leading from cnidarians to mammals. General significance: We show that ThTPase activity is not restricted to mammals as previously thought but is an acquisition of early metazoans. This, and the identification of critically important residues, allows us to draw an evolutionary perspective of the CYTH family of proteins. [less ▲]

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See detailDiversity of mechanisms involved in aromatase regulation and estrogen action in the brain
Charlier, Thierry ULg; Cornil, Charlotte ULg; Ball, Gregory et al

in Biochimica et Biophysica Acta - General Subjects (2010)

Background In recent years, the mechanisms through which estrogens modulate neuronal physiology, brain morphology, and behavior have proven to be far more complex than previously thought. For example, a ... [more ▼]

Background In recent years, the mechanisms through which estrogens modulate neuronal physiology, brain morphology, and behavior have proven to be far more complex than previously thought. For example, a second nuclear estrogen receptor has been identified, a new family of coregulatory proteins regulating steroid-dependent gene transcriptions was discovered and, finally, it has become clear that estrogens have surprisingly rapid effects based on their actions on cell membranes, which in turn result in the modulation of intracellular signaling cascades. Scope of review This paper presents a selective review of new findings in this area related to work in our laboratories, focusing on the role of estrogens in the activation of male sexual behavior. Two separate topics are considered. We first discuss functions of the steroid receptor coactivator-1 (SRC-1) that has emerged as a key limiting factor for behavioral effects of estradiol. Knocking-down its expression by antisense oligonucleotides drastically inhibits male-typical sexual behaviors. Secondly, we describe rapid regulations of brain estradiol production by calcium-dependent phosphorylations of the aromatase enzyme, themselves under the control of neurotransmitter activity. These rapid changes in estrogen bioavailability have clear behavioral consequences. Increases or decreases in estradiol concentrations respectively obtained by an acute injection of estradiol itself or of an aromatase inhibitor lead within 15–30 min to parallel changes in sexual behavior frequencies. These new controls of estrogen action offer a vast array of possibilities for discrete local controls of estrogen action. They also represent a formidable challenge for neuroendocrinologists trying to obtain an integrated view of brain function in relation to behavior. [less ▲]

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See detailReactivity towards singlet oxygen of propofol inside liposomes and neuronal cells
Heyne, Belinda; Brault, Daniel; Fontaine-Aupart, Marie-Pierre et al

in Biochimica et Biophysica Acta - General Subjects (2005), 1724

Singlet oxygen (1O2), a reactive oxygen species, has been found to be implicated in many cellular events and pathological disorders.Herein, we investigated the reactivity of 1O2 towards the anaesthetic ... [more ▼]

Singlet oxygen (1O2), a reactive oxygen species, has been found to be implicated in many cellular events and pathological disorders.Herein, we investigated the reactivity of 1O2 towards the anaesthetic agent propofol (PPF) encapsulated within DMPC liposomes. By time resolved luminescence, the rate constant of 1O2 quenching by PPF was evaluated, depending on the location of the sensitizer. The nature of the oxidation product, resulting from the reaction of 1O2 with PPF, was determined using absorption and HPLC techniques. Finally, the in vitro protective effect of PPF towards the1O2-induced neuronal cell toxicity was evaluated in terms of cell viability. [less ▲]

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See detailHemolytic activity of new linear surfactin analogs in relation to their physico-chemical properties
Dufour, Samuel; Deleu, Magali ULg; Nott, Katherine ULg et al

in Biochimica et Biophysica Acta - General Subjects (2005), 1726

New linear analogs of surfactin have been synthesized. Their physico-chemical parameters were determined. The results indicate that these linear products show surface activities although they are lowered ... [more ▼]

New linear analogs of surfactin have been synthesized. Their physico-chemical parameters were determined. The results indicate that these linear products show surface activities although they are lowered compared to those of cyclic compounds. The hemolytic activities have also been assayed. In contrast with cyclic surfactins, no significant hemolysis occurs for the linear products in the range of concentrations tested. Moreover, a protective effect against Triton X-100 induced hemolysis has been highlighted for linear surfactins. The concentration at which this protective effect happens is correlated directly to the CMC, and inversely to the acyl chain length of the product. In a hypotonic medium, analogs having a long acyl chain tend to increase the hemolysis, meanwhile the product with the shortest chain tends to decrease it. [less ▲]

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See detailPig tissues express a catalytically inefficient 25-kDa thiamine triphosphatase: Insight in the catalytic mechanisms of this enzyme
Szyniarowski, Piotr; Lakaye, Bernard ULg; Czerniecki, Jan ULg et al

in Biochimica et Biophysica Acta - General Subjects (2005), 1725(1), 93-102

Thiamine triphosphate (ThTP) is found in most organisms and may be an intracellular signal molecule produced in response to stress. We have recently cloned the cDNA coding for a highly specific mammalian ... [more ▼]

Thiamine triphosphate (ThTP) is found in most organisms and may be an intracellular signal molecule produced in response to stress. We have recently cloned the cDNA coding for a highly specific mammalian 25-kDa thiamine triphosphatase. The enzyme was active in all mammalian species studied except pig, although the corresponding mRNA was present. In order to determine whether the very low ThTPase activity in pig tissues is due to the absence of the protein or to a lack of catalytic efficiency, we expressed human and pig ThTPase in E. coli as GST fusion proteins. The purified recombinant pig GST-ThTPase was found to be 2-3 orders of magnitude less active than human GST-ThTPase. Using site-directed mutagenesis, we show that, in particular, the change of Glu85 to lysine is responsible for decreased solubility and catalytic activity of the pig enzyme. Immunohistochemical studies revealed a distribution of the protein in pig brain very similar to the one reported in rodent brain. Thus, our results suggest that a 25-kDa protein homologous to hThTPase but practically devoid of enzyme activity is expressed in pig tissues. This raises the possibility that this protein may play a physiological role other than ThTP hydrolysis. [less ▲]

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See detailAscididemin and meridine stabilise G-quadruplexes and inhibit telomerase in vitro
Guittat, Lionel; De Cian, Anne; Rosu, Frédéric ULg et al

in Biochimica et Biophysica Acta - General Subjects (2005), 1724(3), 375-384

Ascididemin and Meridine are two marine compounds with pyridoacridine skeletons known to exhibit interesting antitumour activities. These molecules have been reported to behave like DNA intercalators. In ... [more ▼]

Ascididemin and Meridine are two marine compounds with pyridoacridine skeletons known to exhibit interesting antitumour activities. These molecules have been reported to behave like DNA intercalators. In this study, dialysis competition assay and mass spectrometry experiments were used to determine the affinity of ascididemin and meridine for DNA structures among duplexes, triplexes, quadruplexes and single-strands. Our data confirm that ascididemin and meridine interact with DNA but also recognize triplex and quadruplex structures. These molecules exhibit a significant preference for quadruplexes over duplexes or single-strands. Meridine is a stronger quadruplex ligand and therefore a stronger telomerase inhibitor than ascididemin (IC50= 11 and > 80 mu M, respectively in a standard TRAP assay). (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailSolubilization of Thiamine Triphosphatase from the Electric Organ of Electrophorus Electricus
Bettendorff, Lucien ULg; Longree, Isabelle; Wins, Pierre et al

in Biochimica et Biophysica Acta - General Subjects (1991), 1073(1), 69-76

The membrane-associated, anion-regulated thiamine triphosphatase from Electrophorus electricus electric organ can be solubilized by various neutral detergents. Polyoxyethylene ethers are the most ... [more ▼]

The membrane-associated, anion-regulated thiamine triphosphatase from Electrophorus electricus electric organ can be solubilized by various neutral detergents. Polyoxyethylene ethers are the most effective. Anionic detergents readily inactivate the enzyme. A 6.4-fold increase in specific activity is obtained by successive treatment of crude membranes with octanoyl-N-methylglucamide, which solubilized other proteins, and Lubrol-PX with releases 60% of the thiamine triphosphatase (TTPase) activity. Solubilization by Lubrol-PX rapidly modifies kinetic parameters. The Km, Vmax and pH optimum are decreased. However, the solubilized TTPase may be kept at 0 degrees C for many hours without further change in specific activity. At 35 degrees C, the half-life is still 83 min at pH 5.0, but denaturation becomes rapid at pH greater than or equal to 7. Solubilization modifies anion effects on TTPase activity. The activating effect of nitrate is nearly lost, while inhibition by sulfate is no longer time-dependent. [less ▲]

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See detailPurification and properties of the exocellular β-lactamase of Actinomadura strain R39
Duez, Colette ULg; Frère, Jean-Marie ULg; Ghuysen, Jean-Marie ULg et al

in Biochimica et Biophysica Acta - General Subjects (1982), 700

The exocellular beta-lactamase (penicillin amido-beta-lactamhydrolase, EC 3.5.2.6) of Actinomadura R39 consists of one single polypeptide chain of molecular weight about 15 200. It exhibits a highly ... [more ▼]

The exocellular beta-lactamase (penicillin amido-beta-lactamhydrolase, EC 3.5.2.6) of Actinomadura R39 consists of one single polypeptide chain of molecular weight about 15 200. It exhibits a highly asymmetrical shape, has a low isoelectric point (at pH 5.0) and contains about 9.3% (w/w) of a polydeoxyribonucleotide with which it forms a rather stable complex. Removal of a substantial amount of this deoxyribonucleotide by treatment with DNAase I has no effect on the enzyme activity. The beta-lactamase has a wide spectrum of activity. Penicillins and delta 3-cephalosporins can be either good or poor substrates. Oxacillin, which is a poor substrate of most beta-lactamases from Gram-positive bacteria, is a good substrate of the beta-lactamase of Actinomadura R39. Its best substrate, however, is nitrocefin (kcat/Km: 2300 000 M-1.s-1; catalytic centre activity: 210 s-1). The kcat/Km values observed with some penicillins and delta 3-cephalosporins are similar to the values of the bimolecular rate constants that govern the formation of the acyl-enzyme intermediates between these antibiotics and the serine D-alanyl-D-alanine peptidase that is also secreted by the same strain Actinomadura R39. Such a relationship, however, is not observed with all the beta-lactam compounds tested. [less ▲]

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See detailStudies on the primary structures of the exocellular D-Alanyl-D-Alanine peptidases of Streptomyces strain R61 and Actinomadura strain R39
Duez, Colette ULg; Frère, Jean-Marie ULg; Ghuysen, Jean-Marie ULg et al

in Biochimica et Biophysica Acta - General Subjects (1981), 671

The Mr 37 000 D-alanyl-D-alanine peptidase excreted by Streptomyces R61 and the Mr 53 000 D-alanyl-D-alanine peptidase excreted by Actinomadura R39 are both characterized by a very uneven distribution of ... [more ▼]

The Mr 37 000 D-alanyl-D-alanine peptidase excreted by Streptomyces R61 and the Mr 53 000 D-alanyl-D-alanine peptidase excreted by Actinomadura R39 are both characterized by a very uneven distribution of the basic (Arg + Lys) amino acid residues. Trypsin degradation of the heat-denatured enzymes generates (1) thirteen soluble peptides which contain from 2 to 28 residues in the case of the R61 enzyme and nineteen soluble peptides which contain 2 to 39 residues in the case of the R39 enzyme; and (2) three large segments or core peptides which, irrespective of the enzymes from which they originate, consist of 50-60, 70-80 and 110-120 residues. About 90% of the basic (Arg + Lys) amino acid residues are recovered in the soluble tryptic peptides. The core peptides represent 62% (Mr approximately 23 000) and 45% (Mr approximately 24 000) of the untreated R61 and R39 enzymes, respectively. One 28-residue soluble peptide isolated from the R61 enzyme represents the N-terminal portion of the protein whose sequence has been established. The penicillin attachment site of the R61 enzyme has been located in one of the core peptides. For the R39 enzyme, indirect evidence shows that the penicillin binding site is probably within one of the soluble peptides. [less ▲]

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See detailOccurrence of N-glycolylmuramic acid in bacterial cell walls: a preliminary survey
Azuma, I.; Thomas, D. W.; Adam, A. et al

in Biochimica et Biophysica Acta - General Subjects (1970), 208(3), 444-451

The N-acyl substituent of muramic acid in the cell walls of some species of Actinomycetales and of the related family of Corynebacteriaceae has been studied. The N-glycolyl derivative, recently identified ... [more ▼]

The N-acyl substituent of muramic acid in the cell walls of some species of Actinomycetales and of the related family of Corynebacteriaceae has been studied. The N-glycolyl derivative, recently identified in Mycobacterium smegmatis, has been found in the three other species of Mycobacterium studied: M. kansasii, M. tuberculosis BCG, and M. phlei. The classical N-acetyl derivative has been found in Streptomyces albus and Corynebacterium fermentans. [less ▲]

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