Search PubMed⌕ Search

Biomedical subjects

J Torreilles

Publications and source records attributed to J Torreilles.

At least 37 records · Page 2Linked to original sources
PubMed1993

Boomerang effect between [Met]-enkephalin derivatives and human polymorphonuclear leukocytes.

[Met]-enkephalin or its precursor, pre-[Met]-enkephalin, were exposed to activated oxygen species produced by human phorbol myristate acetate (PMA)-stimulated polymorphonuclear leukocytes (PMNs) and then analyzed by high-pressure liquid chromatography (HPLC). The chromatograms recorded at the tyrosine maximum wavelength (lambda em 300 nm and lambda ex 280 nm) showed the formation of new peptides by oxidation of methionyl residue in position 5 and ortho, meta, or para hydroxylation of phenylalanyl residue in position 4. The chromatograms recorded at the dityrosine maximum wavelength (lambda em 400 nm and lambda ex 325 nm) showed the formation of new dimeric peptides which contained two [Met]-enkephalin-derivatives linked by a dityrosyl group. These new peptides were tested for chemiluminescence response to PMA-stimulated PMNs. [Met]-enkephalin, pre-[Met]-enkephalin, and the methionyl-oxidized derivatives suppressed the PMA-induced respiratory burst of PMNs. Conversely, after hydroxylation by activated oxygen species released by stimulated PMNs, these peptides enhanced the PMA-induced respiratory burst of PMNs. In the same conditions, dimeric peptides had no effect.

Amino Acid Sequence↗
PubMed1993

Neutrophil-catalysed dimerisation of tyrosyl peptides.

Evidence is given that tyrosyl-peptides are dimerised by polymorphonuclear leukocytes leading to a new family of compounds. The products formed are homo- and hetero-dimeric peptides with linkage between the tyrosyl residues. This corresponds to a dityrosine structure as determined by analytic and spectroscopic data.

Amino Acid Sequence↗
PubMed1993

4-Hydroxynonenal content lower in brains of 25 month old transgenic mice carrying the human CuZn superoxide dismutase gene than in brains of their non-transgenic littermates.

Basic peroxidation in brains of normal 2 month old mice was compared to that in brains of 25 month old mice by measurement of 4-hydroxy-2-nonenal and protein carbonyl contents. No significant age-related differences in 4-hydroxy-2-nonenal were observed, showing that lipid peroxidation is not a determining factor in cerebral aging. However, protein carbonyls increased with age in brains, indicating accumulation of age-related cell constituent damage. The role of excess CuZn superoxide dismutase in basal lipid peroxidation in mouse brains was studied by comparison of eight 25 month old transgenic mice and eight non-transgenic littermates. Higher 4-hydroxy-2-nonenal concentrations were found in normal mouse brains. These data suggest an increased protective role of CuZn superoxide dismutase against lipid peroxidation in transgenic mouse brains.

Aging↗
PubMed1992

Is malonaldehyde a valuable indicator of lipid peroxidation?

Malonaldehyde (MDA), a decomposition product of lipid hydroperoxides which is used as an indicator of oxidative damage to cells and tissues, reacts, in vitro, with hydrogen peroxide to form undetermined degradation products. Since human polymorphonuclear leukocytes (PMNs) release reactive oxygen species including hydrogen peroxide when stimulated with phorbol myristate acetate (PMA), we incubated specific amounts of MDA with resting PMNs and PMA-stimulated PMNs. The amount of MDA recovered after 30 min incubation with stimulated cells, as determined by MDA-thiobarbituric acid assay, was 25% lower than that recovered with resting cells. In the presence of catalase 18% of MDA disappeared and in the presence of superoxide dismutase 15% disappeared. This indicates that measurements of MDA production in living systems, in the presence of reactive oxygen species, could be underestimated.

Catalase↗
PubMed1992

Reciprocal effects between opioid peptides and human polymorphonuclear leukocytes--I. Chemical modifications of Leu-enkephalin by phorbol myristate acetate-stimulated polymorphonuclear leukocytes.

When L-tyrosyl-glycyl-L-phenylalanyl-L-leucine (Leu-enkephalin) is exposed to the activated oxygen species produced by phorbol myristate acetate (PMA)-stimulated polymorphonuclear leukocytes (PMNs), hydroxylation of the phenylalanyl residue in position 4 of the peptide occurs, producing hydroxy-phenylalanyl derivatives which are identified by HPLC analysis and mass spectrometry. Attack of hydroxyl radicals generated by the Cu (II)/ascorbate system upon Leu-enkephalin also produces isomeric o-, m- and p-hydroxy-phenylalanyl derivatives. When PMNs are incubated with a synthetic peptide, L-tyrosyl-glycyl-glycyl-L-tyrosyl-L-leucine used as a model of hydroxylated Leu-enkephalin, their chemiluminescence response to PMA activation is higher than that of PMNs incubated with Leu-enkephalin.

Chromatography, High Pressure Liquid↗
PubMed1992

Reciprocal effects between opioid peptides and human polymorphonuclear leukocytes--II. Enhancement of phorbol myristate acetate-induced respiratory burst in human polymorphonuclear leukocyte by opioid peptides previously exposed to activated oxygen species.

Activated oxygen species (AOS) have often been shown to promote strong modifications in peptide structures and thus in their biological functions. In the present study, the immunomodulatory effects of Leu-enkephalin, beta-endorphin, dynorphin and some fragments are evaluated, before and after exposure of peptides to AOS, by studying their influence on human polymorphonuclear leukocyte (PMN) respiratory burst. None of the tested opioid peptides (modified or not) were shown to affect resting oxidative metabolism in the PMNs. The effects of peptides on phorbol myristate acetate (PMA)-stimulated production of AOS were measured in a lucigenin-enhanced chemiluminescence assay. Before AOS exposure, the opioid peptides suppressed the PMA-stimulated respiratory burst in human PMNs and a U-shaped dose-response relationship was observed. Conversely, after AOS exposure the opioid peptides enhanced the PMA-stimulated respiratory burst in human PMNs and an inverted U-shaped dose-response relationship was observed. In both cases, the maximal effect was reached at peptide concentrations of 10(-10)M-10(-12) M.

Binding Sites↗
PubMed1990

Nickel (II) as a temporary catalyst for hydroxyl radical generation.

Many in vivo studies show peroxidative damage during nickel toxicity, suggesting the generation of oxygen-activated species. Using the murexide (5,5'-nitrilodibarbituric acid ammonium salt) bleaching technique, we attempted to spectroscopically determine whether there are any histidylpeptides-Ni (II) complexes able to catalyze a nickel-dependent reduction of hydrogen peroxide leading to free oxygen radical production. We show that peptides containing the glycyl-glycyl-L-histidyl sequence trigger nickel-dependent production of oxygen radicals which can damage proteins, cause a rapid loss of tryptophan and a significant production of bityrosine and also induce peroxidation of polyunsaturated fatty acids. During the reaction, the histidine residue in the peptide is selectively damaged and breakdown of the peptide switches off hydroxyl-radical production.

Amino Acid Sequence↗
PubMed1990

Nickel (II) complexes of histidyl-peptides as Fenton-reaction catalysts.

Addition of histidyl-peptides containing the glycyl-glycyl-L-histidyl sequence stimulated the catalysis of Ni(II) hydrogen peroxide reduction. Maximum bleaching of murexide or nitrosodimethylaniline was obtained with glycyl-glycyl-L-histidine. A decrease in the bleaching rates was observed upon addition of SOD or hydroxyl radical scavengers, showing that the hydrogen peroxide/Ni(II)/glycyl-glycyl-L-histidine system generated superoxide anions as well as hydroxyl radicals. In contrast, addition of glycyl-glycyl-L-histidine inhibited the Cu(II) hydrogen peroxide reduction. When peptides or proteins were exposed to oxygen radicals produced by Ni(II)/glycyl-glycyl-L-histidine catalysis of hydrogen peroxide reduction, the observed effects were similar to those produced by oxygen radicals generated by water radiolysis or by Fe(II) or Cu(II) mediated Fenton-reactions: hydroxylation of phenylalanine, interchange of disulfides, destruction of tryptophans and dityrosine formation.

Amino Acid Sequence↗
PubMed1986

Influence of coenzyme structure on the transient chemical intermediate formed during horse-liver alcohol-dehydrogenase-catalyzed reduction of aromatic aldehydes.

The influence of coenzyme structure on the transient chemical intermediate formed in the reaction between the horse-liver alcohol dehydrogenase-NADH complex and an aromatic aldehyde such as 4-trans-(N,N-dimethylamino)cinnamaldehyde or 4-(N,N-dimethylamino)benzaldehyde was investigated by substituting various adenylic dinucleotides for NADH. Two classes of dinucleotide were studied. (a) Dinucleotides which, in the presence of horse-liver alcohol dehydrogenase and either 4-(N,N-dimethylamino)benzaldehyde or 4-trans-(N,N-dimethylamino)cinnamaldehyde, lead to a chromophore structurally analogous to the transient chemical intermediate formed with NADH under the same experimental conditions. This includes dinucleotides with a neutral 1,4-dihydropyridine ring, analogues of NADH and adducts of NAD+ (or analogues) with enolizable carbonyl compounds. (b) Dinucleotides which, under the same experimental conditions, do not form any new chromophores when mixed with horse-liver alcohol dehydrogenase and either 4-trans-(N,N-dimethylamino)cinnamaldehyde or 4-trans-(N,N-dimethylamino)benzaldehyde. This includes oxidized coenzyme analogues, NADPH and NADP+ adducts. Our data suggest that a neutral 1,4-dihydropyridine ring is crucial for the formation of the transient chemical intermediate. When the NAD+-sulphite complex, which has a 1,4-dihydronicotinamide structure and a positive charge at position 4 neutralized by sulphite ions, was substituted for NADH, the transient chemical intermediate chromophore was observed. The implications of this phenomenon are examined by assuming the existence of intermediate-activated forms of substrates and coenzymes during the horse-liver alcohol dehydrogenase catalytic reduction of aldehydes.

Alcohol Dehydrogenase↗
PubMed1986

Rapid separation of dehydrogenases by affinity chromatography with new induced specificity phases.

We describe a procedure using immobilized nicotinamide as an affinity chromatographic ligand for the binding of NAD(P)+-dependent dehydrogenases. The procedure involves preparation of nicotinamide N1-(N-(6-aminohexyl)-acetamide)-agarose and modification of the immobilized nicotinamide by the addition of a ketone or an aldehyde to form an adduct. The nicotinamide, which has no affinity for dehydrogenase, becomes a very specific ligand of dehydrogenase, which binds the ketone or the aldehyde as substrate or inhibitor. In tests, the adduct prepared with immobilized nicotinamide and sodium pyruvate bound specifically to lactate dehydrogenase (EC 1.1.1.27), whereas the adduct prepared with alpha-ketoglutarate bound to glutamate dehydrogenase (EC 1.4.1.3). This technique enables the rapid isolation of a given dehydrogenase.

Alcohol Dehydrogenase↗
PubMed1985

[Simple compounds with high pharmacologic potential: beta-carbolines. Origins, syntheses, biological properties].

We reviewed the origins, the synthetic pathways and the biological properties of beta-carbolines, the condensation products of tryptophan and indole alkylamines with aldehydes. They were found in many plants, some of which have been used as hallucinogens. They also occur as minor constituents in tobacco smoke. In mammalian body, beta-carboline derivatives occur normally in plasma, platelets and urine, moreover it seems that some are formed in human body after alcohol intake. Due to interesting biological effects described in recent years (inhibition of monoamine oxidase, binding to benzodiazepine receptors, comutagenic and carcinogenic properties, 5-hydroxy tryptamine uptake inhibition), many attempts were made to prepare beta-carbolines starting from various indole derivatives. We reviewed the published methods up to 1975 and summarized the main patents related with pharmacological properties of synthetic beta-carbolines.

Alcohol Drinking↗
PubMed1983

The structure of the abortive nicotinamide adenine dinucleotide-pyruvate-lactate dehydrogenase complex as determined by circular dichroism.

Both ternary complexes consisting of lactate dehydrogenase-NAD+ and pyruvate or alpha ketobutyrate were compared, by means of circular dichroism spectra, with the corresponding binary complexes formed between lactate dehydrogenase and both NAD-pyruvate and NAD-alpha ketobutyrate adducts. Strong differences were observed. They disappeared when the ternary complexes were dissociated by addition of urea. This behaviour is explained by assuming the existence, in the abortive ternary complexes of a NAD+ activated transient form having a partial carbonium ion at position 4. Such a structure may account for the abortive and for the evolutive ternary complexes of the dehydrogenases as well as for the chemical synthesis mechanism of adducts.

Animals↗
PubMed1982

Binding of adducts of NAD(P) and enolizable ketones to NAD(P)-dependent dehydrogenases.

Carbonyl compounds such as alpha-ketoglutarate, pyruvate, oxaloacetate, butyraldehyde, acetaldehyde or acetone react with NAD or NADP to give adducts. Binding studies of adducts to dehydrogenases are performed by means of ultraviolet differential spectroscopy, circular dichroism and spectrofluorimetry. The dehydrogenases show a high degree of binding specificity toward the adducts which contain their specific oxidized substrate and their specific coenzyme. The high selectivity of the dehydrogenases for adducts is evidenced by binding studies of NAD(P)-pyruvate and NAD(P)-alpha-ketoglutarate adducts on glutamate dehydrogenase at pH 7.6 and 8.9. Evidence is presented showing that adducts bind to the active site of the enzymes.

Alcohol Dehydrogenase↗
PubMed1982

[Affinity chromatography of NAD(P)+ dehydrogenases dependent on the concentration of NAD(P)+ bound to ketones or aldehydes].

The use of general ligands such as NAD(P)+ for affinity chromatography of dehydrogenase requires elution with pulses of oxidized or reduced cofactor at suitable concentrations. This method of elution can involve considerable effort before ideal eluent conditions are evolved. We report on a new method of immobilized NAD(P)+ modifications which increases the selectivity of the phase and may be of rather wide application. The immobilized NAD(P)+ is modified by addition of a ketone or an aldehyde substrate of the dehydrogenase which must be purified and becomes a very specific ligand of that dehydrogenase. The adduct of immobilized NAD+ and sodium pyruvate absorbs specifically the lactate dehydrogenase, whereas the adduct of immobilized NAD+ and cyclohexanone adsorbs specifically the horse liver alcohol dehydrogenase. Absorbed dehydrogenases are eluted with NaCl gradients.

Aldehydes↗
PubMed1982

Studies of covalent adducts of NAD(P) and enolizable ketones as specific glutamate dehydrogenase inhibitors.

Structural analogues of the reduced coenzymes, NADH or NADPH, of dehydrogenases are prepared by addition of carbonyl compounds including: pyruvate, alpha ketoglutarate, oxaloacetate, butyraldehyde, acetaldehyde and acetone, to the oxidized coenzymes NAD(P). Some of the adducts obtained are specific inhibitors of the glutamate dehydrogenase. The specificity is related to the carbonyl compound used. The high selectivity of the dehydrogenases for adducts is evidenced by inhibition studies of NAD(P)-pyruvate and NAD(P)-alpha ketoglutarate adducts on both activities of glutamate dehydrogenase. The inhibitions are competitive with the reduced coenzymes and the oxidized substrates: adducts could be considered as structures closely related to the ternary complexes of the dehydrogenase.

Animals↗
PubMed1982

NAD(P) adducts as protective agents against glutamate dehydrogenase inactivation by pyridoxal 5'-phosphate: a tool for the study of oxidized coenzyme activated state in enzymatic evolutive and abortive complexes.

Glutamate dehydrogenase is reversibly inhibited by the reaction of 1 mole of pyridoxal 5'-phosphate per mole of subunit of the enzyme polypeptide chain. We have shown that NAD(P) adducts as well as NMNH protect the glutamate dehydrogense against this reversible inactivation in the same way as reduced coenzymes. These data lead to the conclusion that it is the 1,4-dihydronicotinamide structure that is responsible for protecting the enzyme. NAD+ and NMN+ do not protect the enzyme, but in the presence of the oxidized substrate NAD+ became a good protecting agent whereas NMN+ remained ineffective. To explain the protection exerted by NAD+ in the presence of oxidized substrate, a transient activated form of the oxidized coenzyme with a 1,4-dihydronicotinamide structure and a positive charge on the C-4 atom is postulated.

Animals↗