Étude par diffraction de neutrons de Ho2C

La structure rhomboédrique de Ho₂C ordonné a été précisée par diffraction de neutrons. On peut la considérer comme un empilement, normalement à l'axe ternaire d'une succession de couches Ho — C — Ho — □… . La structure magnétique ordonnée est complexe.Bacchella G. L., Mériel Pierre, Pinot M., Lallement R. Étude par diffraction de neutrons de Ho2C. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 89, 2, 1966. pp. 226-228

Structure of L-aspartate oxidase : implications for the succinate dehydrogenase/fumarate reductase oxidoreductase family

Background: Given the vital role of NAD+ in cell metabolism, the enzymes involved in bacterial de novo NAD+ biosynthesis are possible targets for drug design against pathogenic bacteria. The first reaction in the pathway is catalysed by L-aspartate oxidase (LASPO), a flavoenzyme that converts aspartate to iminoaspartate using either molecular oxygen or fumarate as electron acceptors. LASPO has considerable sequence homology with the flavoprotein subunits of succinate dehydrogenase (SDH) and fumarate reductase (FRD). Results: The crystal structure of the apoform of LASPO from Escherichia coli has been determined to 2.2 \uc5 resolution. The enzyme shows a novel fold for an FAD-dependent protein, comprising a three-domain structure: an FAD-binding domain with the dinucleotide-binding fold, a C-terminal three- helical bundle domain, and an \u3b1+\u3b2 capping domain, which is topologically similar to the small subunit of spinach ribulose-1,5-bisphosphate carboxylase/oxygenase. The interface between the FAD-binding and capping domains defines a cleft in which the active site is located. Conclusions: A number of strictly conserved residues present in all three domains indicate that LASPO, SDH and FRD share the same overall folding topology. Many of these conserved residues are in the FAD-binding site and active centre, suggesting a similar catalytic mechanism. Thus, LASPO, SDH and FRD form a class of functionally and structurally related oxidoreductases that are all able to reduce fumarate and to oxidise a dicarboxylate substrate

Headache and reproductive life.

Indagine sui rapporti che legano la cefalea, e in particolare l'emicrania, con gli eventi della vita riproduttiva femminil

Structure of L-aspartate oxidase: implications for the succinate dehydrogenase/fumarate reductase oxidoreductase family

BACKGROUND: Given the vital role of NAD+ in cell metabolism, the enzymes involved in bacterial de novo NAD+ biosynthesis are possible targets for drug design against pathogenic bacteria. The first reaction in the pathway is catalysed by L-aspartate oxidase (LASPO), a flavoenzyme that converts aspartate to iminoaspartate using either molecular oxygen or fumarate as electron acceptors. LASPO has considerable sequence homology with the flavoprotein subunits of succinate dehydrogenase (SDH) and fumarate reductase (FRD). RESULTS: The crystal structure of the apoform of LASPO from Escherichia coli has been determined to 2.2 A resolution. The enzyme shows a novel fold for an FAD-dependent protein, comprising a three-domain structure: an FAD-binding domain with the dinucleotide-binding fold, a C-terminal three-helical bundle domain, and an alpha + beta capping domain, which is topologically similar to the small subunit of spinach ribulose-1,5-bisphosphate carboxylase/oxygenase. The interface between the FAD-binding and capping domains defines a cleft in which the active site is located. CONCLUSIONS: A number of strictly conserved residues present in all three domains indicate that LASPO, SDH and FRD share the same overall folding topology. Many of these conserved residues are in the FAD-binding site and active centre, suggesting a similar catalytic mechanism. Thus, LASPO, SDH and FRD form a class of functionally and structurally related oxidoreductases that are all able to reduce fumarate and to oxidise a dicarboxylate substrate

Crystallization of L-aspartate oxidase, the first enzyme in the bacterial de novo biosynthesis of NAD

The flavoenzyme L-aspartate oxidase from Escherichia coli was crystallized using the hanging-drop vapour-diffusion technique with PEG 4000 as precipitant. The crystals belong to space group P3121 (or P3221) with unit-cell parameters a = b = 84.9, c = 159.9 \uc5. A solvent content of 42% corresponds to a monomer (60 kDa) in the asymmetric unit. A complete 2.8 \uc5 resolution data set was collected using a rotating-anode X-ray generator

CG5/Dx human breast cancer cell line: characterization of a new doxorubicin-resistant variant

By continuous exposure of CG5 human breast cancer cell line to increasing doxorubicin (Dx) concentrations, a multidrug-resistant (MDR) subline (CG5/Dx) was obtained. The resistant variant showed P-glycoprotein (P-gp) expression and a lower intracellular doxorubicin level than the parental cells. CG5/Dx cells were 19.4 fold more resistant to Dx than CG5 cells and showed a cross-resistance to some structurally related and unrelated compounds. Differences in kinetics, biological and ultrastructural features between the two cell lines were investigated. The CG5/Dx cells grew more slowly, produced higher CEA levels and showed a reduced progesterone receptor (PgR) content than the parental cells. Ultrastructural studies revealed differences involving, polyribosomes, rough endoplasmic reticulum, [mitochondria] and cytoskeleton

Changes in serum levels of N-terminal procollagen type III propeptide as an index of postinfarction ventricular remodeling

The levels of aminoterminal propeptide of type III procollagen (PIIINP) can be used as an index of collagen breakdown. The aim of our study was to evaluate modifications in serum concentration of PIIINP (PIIINPs) in patients with a first episode of myocardial infarction. We examined 70 patients admitted at our Institution for acute myocardial infarction and 10 normal subjects. PIIINPs dosage was obtained by radioimmunoassay method utilizing a commercial available kit. All patients underwent three PIIINPs dosages: within 24 hours after admission, at 6 and 12 months after myocardial infarction. Control values were 0.4 +/- 0.1 U/ml. In 38 patients (Group I) PIIINPs levels increased at 6 and 12 months after infarction: 0.53 +/- 0.2, 0.75 +/- 0.2 and finally 0.76 +/- 0.1 U/ml. In the remaining 32 patients (Group II) PIIINPs values increased at 6 months and then returned to baseline at 12 months: 0.56 +/- 0.2, 0.75 +/- 0.1 and then 0.46 +/- 0.1 U/ml. The end-diastolic volume index did not change significantly in Group I (from 93.7 +/- 21 to 79.7 +/- 20 ml/m2) while it decreased after 12 months in Group II (from 88.9 +/- 13 to 58.6 +/- 11 ml/m2; confidence interval 95% from 2 to 55 ml/m2; p = 0.03). Similarly, there was no significant variation in end-systolic volume index (ESVI, from 39.7 +/- 11 to 36.9 +/- 11 ml/m2) and ejection fraction (from 60 +/- 10 to 59 +/- 15%) in Group I; while in Group II ESVI decreased significantly (from 33.6 +/- 13 to 20 +/- 5 ml/m2, confidence interval 95% from 3 to 24 ml/m2; p = 0.02) and ejection fraction improved (from 62 +/- 11 to 72 +/- 15%; confidence interval 95% from -20 to -1%; p = 0.04). In conclusion, patients with elevated levels of PIIINPs at 12 months did not improve ventricular function while patients with PIIINPs returning to baseline at 12 months had an improvement. Our results suggest an active participation of newly formed collagen in post-infarct ventricular remodeling. Therefore PIIINPs may be a marker of this process

Crystallization of L-aspartate oxidase, the first enzyme in the bacterial de novo biosynthesis of NAD.

The flavoenzyme L-aspartate oxidase from Escherichia coli was crystallized using the hanging-drop vapour-diffusion technique with PEG 4000 as precipitant. The crystals belong to space group P3121 (or P3221) with unit-cell parameters a = b = 84.9, c = 159.9 A. A solvent content of 42% corresponds to a monomer (60 kDa) in the asymmetric unit. A complete 2.8 A resolution data set was collected using a rotating-anode X-ray generator