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D Legrand

Publications and source records attributed to D Legrand.

At least 19 recordsLinked to original sources
PubMed1992

Crystallization and preliminary X-ray diffraction study of Lathyrus ochrus isolectin II complexed to the human lactotransferrin N2 fragment.

Isolectin II (LOL II) isolated from the seeds of Lathyrus ochrus has been crystallized in the presence of the N2 fragment (18,500 Da) isolated from human lactotransferrin, which contains an N-acetyllactosamine type biantennary glycan linked to Asn137. This is the first example of a legume lectin crystallized with an N-glycosylprotein. Crystals of the LOL II-N2 complex belong to the tetragonal space group (P4(1)2(1)2 or the enantiomorph) with cell dimensions: a = b = 63.5 A, c = 251.9 A. They diffract well up to at least 3.5 A resolution and more weakly up to 2.8 A resolution. Assuming one functional half-entity in the asymmetric unit, an alpha, beta monomer complexed to one N2 fragment (24,500 Da + 18,500 Da) would give a Vm of 2.95 A3/Da and a solvent content of approximately 58%. SDS/polyacrylamide gels of the dissolved crystals show the presence of both the LOL II and N2 fragment.

Crystallization↗
PubMed1992

Molecular interactions between human lactotransferrin and the phytohemagglutinin-activated human lymphocyte lactotransferrin receptor lie in two loop-containing regions of the N-terminal domain I of human lactotransferrin.

Fluorescein isothiocyanate derivatization of the human lactotransferrin on Lys-264 inhibits the binding of the protein of human PHA-activated lymphocytes [Legrand, D., Mazurier, J., Maes, P., Rochard, E., Montreuil, J., & Spik, G. (1991) Biochem. J. 276, 733-738], indicating that part of the receptor-binding site is located in the N-terminal domain I of lactotransferrin. In the present study, a 6-kDa peptide (residues 4-52) was isolated from the N-terminal lobe of human lactotransferrin which inhibited the binding of the protein to its cell receptor. In addition, lactotransferrin was derivatized using sulfosuccinimidyl 2-(p-azidosalicylamido)ethyl-1,3'-dithiopropionate (SASD) and sulfosuccinimidyl 6-((4'-azido-2'-nitrophenyl)amino)hexanoate (sulfo-SANPAH), two heterobifunctional reagents generally used for receptor-ligand cross-linking. The azide group of these two reagents was inactivated by photolysis, and only the succinimidyl ester group was allowed to react with lysine residues of the protein. The binding of the derivatized lactotransferrins to the human lymphocyte receptor was assayed. SASD, which binds to Lys-74, was able to inhibit the binding of lactotransferrin to the cell receptor, in contrast to Lys-281-binding sulfo-SANPAH. Molecular modeling showed the position of SASD, sulfo-SANPAH, and fluorescein molecules at the surface of the protein and suggested that SASD and fluorescein could mask residues 4-6 and two loop-containing regions of human lactotransferrin (residues 28-34 and 38-45). The comparison of the primary and tertiary structures of human lactotransferrin and serotransferrin, which bind to specific cell receptors, shows that the above-mentioned regions, which are likely involved in protein-receptor interactions, possess specific structural features.

Amino Acid Sequence↗
PubMed1991

Inhibition of the specific binding of human lactotransferrin to human peripheral-blood phytohaemagglutinin-stimulated lymphocytes by fluorescein labelling and location of the binding site.

Labelling of human lactotransferrin with fluorescein 5'-isothiocyanate (FITC) in an equimolar ratio inhibits the binding of the protein to phytohaemagglutinin-activated human peripheral-blood lymphocytes. Therefore it can be assumed that FITC reacts at, or near, the receptor-binding site. Three FITC-labelled peptides have been purified from a tryptic digest of the FITC-labelled lactotransferrin. The determination of their amino acid sequence and their localization on the primary structure of the protein permitted the identification of two FITC-accessible areas in the N-terminal lobe and one in the C-terminal lobe. In fact, only 10% of the total FITC was conjugated to one lysine residue (Lys579) of the C-terminal lobe, whereas most (80%) of the FITC was conjugated to three close lysine residues [Lys263 (65% of total fluorescence), Lys280 and Lys282 (15% of total fluorescence)] located in beta-turn structures, of the N-terminal domain I of human lactotransferrin. The results obtained show that the receptor-binding site should be located in the vicinity of the FITC-accessible Lys263, Lys280 and Lys282, and corroborate our preliminary results reporting the involvement of the N-terminal domain I in the binding of human lactotransferrin to mitogen-stimulated lymphocytes [Rochard, Legrand, Mazurier, Montreuil & Spik (1989) FEBS Lett. 255, 201-204]. In any case, FITC labelling is not suitable for studying the binding of lactotransferrin to activated lymphocytes and its use may lead to erroneous interpretations of cell binding experiments.

Amino Acid Sequence↗
PubMed1990

Properties of the iron-binding site of the N-terminal lobe of human and bovine lactotransferrins. Importance of the glycan moiety and of the non-covalent interactions between the N- and C-terminal lobes in the stability of the iron-binding site.

The recent determination by X-ray diffraction of the tridimensional structure of human lactotransferrin has underlined the presence of two lobes, each composed of two domains, I and II, as well as the involvement of five ligands in the binding of iron. Only one of the ligands (Asp-61) is located in domain I (residues 1-90 and 252-320), while the others [two tyrosine, one histidine and one (bi)carbonate ion linked to an arginine residue] belong to domain II (residues 91-251). On the basis of these data and of our previous results concerning the isolation of the 30 kDa N-tryptic fragment (residues 4-281) and the 20 kDa N2-glycopeptide (N-terminal domain II; residues 91-253) from human and bovine lactotransferrins, we have compared the iron-binding properties of these two fragments. The results demonstrate that Asp-61, which is missing from domain II, does not take part in the stability upon protonation of the iron complex of both human and bovine lactotransferrins. Furthermore, by comparing the iron-binding properties of human and bovine lactotransferrins to those of isolated 30 kDa N-tryptic and 50 kDa C-tryptic fragments and of the reassociated N,C-tryptic complex of both proteins, it has been shown that the non-covalent interactions which occurred between the two lobes of lactotransferrins and in the reassociated N,C-tryptic complex can explain in part the high affinity of lactotransferrins for iron. Finally, deglycosylation experiments on the 30 kDa N-tryptic fragment and N-terminal domain II from human and bovine lactotransferrins demonstrate that full removal of the glycan moiety leads to the loss of iron-binding capacity and so underlines the importance of the glycan moiety in the stability upon protonation of the N-terminal iron-binding site of both lactotransferrins.

Animals↗
PubMed1989

The N-terminal domain I of human lactotransferrin binds specifically to phytohemagglutinin-stimulated peripheral blood human lymphocyte receptors.

Human lactotransferrin receptors have been recently characterized on mitogen-stimulated human lymphocytes [(1989) Eur. J. Biochem. 179, 481-487]. In order to define the lactotransferrin recognition site by these receptors, the binding to lymphocytes of several tryptic fragments, isolated from human lactotransferrin by mild tryptic hydrolysis [(1984) Biochim. Biophys. Acta 787, 90-96], has been investigated. The 30 kDa N-tryptic fragment (residues 4-281) and the re-associated N,C-tryptic complex bind to lactotansferrin lymphocyte receptor with a dissociation constant of 44 nM and 39 nM, respectively, similar to the value obtained for the native lactotransferrin (Kd = 46 nM). However, neither the N-terminal domain II (residues 91-257) nor the 50 kDa C-tryptic fragment (residues 282-703) are recognized. These results suggest that the binding site of human lactotransferrin by the lymphocyte receptor is located in the N-terminal lobe and more precisely in the N-terminal domain I (residues 4-90 and/or 258-281).

Binding Sites↗
PubMed1989

Expression of human lactotransferrin receptors in phytohemagglutinin-stimulated human peripheral blood lymphocytes. Isolation of the receptors by antiligand-affinity chromatography.

In the resting rate, the human peripheral blood lymphocytes did not show detectable surface and intracellular receptors for human lactotransferrin. However, both types of lactotransferrin receptors were expressed during stimulation of lymphocytes with phytohemagglutinin. The appearance of receptors was time-dependent and the number of receptors reached a plateau after at least two days of mitogen stimulation. These results suggest that the presence of surface receptors on mitogen-stimulated lymphocytes is not consecutive to a modification of subcellular distribution but to an induction of biosynthesis of the receptors. As measured by incorporation of [3H]thymidine into DNA, addition of human lactotransferrin in a serum-free medium increased the proliferative activity of phytohemagglutinin-stimulated lymphocytes. Optimal enhancement of [3H]thymidine incorporation was obtained by adding 30% iron-saturated lactotransferrin at a concentration of 0.17 microM. Therefore, the role of lactotransferrin in the response of lymphocytes to mitogen stimulation appears to be similar to that previously described for serotransferrin. The lactotransferrin receptor was visualized using 125I-labeled lactotransferrin on nitrocellulose paper after electroblotting of the Triton X-100 extract of the phytohemagglutinin-stimulated lymphocytes as two protein bands of 100 and 110 kDa molecular mass. Purification of the lactotransferrin receptor from the Triton-X-100-soluble extract of stimulated lymphocytes was performed by antiligand-affinity chromatography. The binding of lactotransferrin to the purified receptors was reversible and dependent on concentration and pH.

Cell Membrane↗
PubMed1988

[Postoperative hypoglycemia after excision of pheochromocytoma. A case].

A case of hypoglycaemia consecutive to excision of a bilateral phaeochromocytoma in a 33-year old patient with Sipple's syndrome is reported. The severity of the hypoglycaemia (1.3 mmol/l) accounted for the brain lesions which ultimately resulted in the patient's death. Eight cases of hypoglycaemia occurring in similar circumstances have been published. The condition is due to the massive release of insulin during the hours that follow removal of the tumour. This results in the persistence of the peri-operative hyperglycaemic stimulation and in the suppression of the previous inhibition of insulin secretion due to alpha-adrenergic stimulation of catecholamines in the beta-cells of Langerhans' islets.

Adrenal Gland Neoplasms↗
PubMed1988

Structure and spatial conformation of the iron-binding sites of transferrins.

Transferrins are iron-binding glycoproteins involved in iron metabolism and antibacterial defense mechanisms. Since the discovery of transferrins, many studies have attempted to characterize the iron ligands and to establish the conformation of the iron-binding sites. From chemical and spectroscopic studies, it was generally accepted that iron was hexacoordinated to Tyr and His residues, to a water molecule and to a (bi)carbonate ion, electrostatically linked to an Arg residue. On the basis of these studies, on the one hand, and on the basis of the homologies between the amino acid sequences of transferrins, on the other hand, predicted data have been provided about the number and location of the iron ligands. Recent X-ray crystallography studies of human lactotransferrin have partially confirmed the above-mentioned predicted data and have brought invaluable information about the nature of the ligands and the conformation of the iron-binding site. On the basis of the obtained results, a scheme has been proposed in which the iron is coordinated to 2 Tyr, 1 His and 1 Asp residues, to a (bi)carbonate linked to an Arg residue and probably to a water molecule. The iron-binding site is located at the interface between the two domains which constitute each lobe of the transferrins.

Amino Acid Sequence↗
PubMed1987

Identification of a major 72 kilodalton surface antigen in twelve isolates of Leishmania braziliensis braziliensis.

The study of the surface antigens of Leishmania braziliensis braziliensis revealed a great homogeneity among ten strains isolated from Bolivia and two reference strains from Brazil and Belize. A 72 kDa major protein, present in all L. b. braziliensis strains, was recognized by both cutaneous and mucocutaneous human sera, but was not recognized by Kala-azar and chagasic sera. No cross-reactive antigens were found among strains of Leishmania braziliensis guyanensis, Leishmania braziliensis panamensis, Leishmania mexicana amazonensis and Leishmania donovani chagasi testing these strains with hamster and human anti-L. b. braziliensis sera. Moreover, these strains possessed major antigens with molecular weights different from those of L. b. braziliensis strains. A microheterogeneity of L. b. braziliensis surface antigens was detected for the high molecular weight antigens and seemed to be related to the isoenzymic microheterogeneity.

Animals↗
PubMed1986

Evidence for interactions between the 30 kDa N- and 50 kDa C-terminal tryptic fragments of human lactotransferrin.

Gel filtration of a mild tryptic digest of diferric human lactotransferrin carried out in presence of 10% (v/v) acetic acid led to the isolation of two fragments, an N-terminal tryptic fragment having an Mr of 30,000 and a C-terminal tryptic fragment having an Mr of 50,000 [Legrand, Mazurier, Montreuil & Spik (1984) Biochim. Biophys. Acta 787, 90-96]. Both fragments possess a degree of organization lower than that of the native protein, as shown by the decrease of about 30% of the alpha-helical content observed by c.d. The two fragments are able to re-associate in neutral solutions, as shown by the isolation, by gel chromatography, of a re-associated 80 kDa N,C-tryptic complex having the chromatographic behaviour of the native lactotransferrin. Computer-based comparison of the measured c.d. spectrum of the mixture of N-tryptic and C-tryptic fragments (molar ratio 1:1) with the spectrum calculated by assuming one molecule of each fragment, shows that the alpha-helix content of lactotransferrin is restored. These results strongly suggest the existence of non-covalent and reversible interactions between the two lobes of lactotransferrin. In addition it was demonstrated that short peptide segments (residues 19-24, 45-58 and 264-276) are involved in the secondary-structure modifications referred to above.

Amino Acids↗
PubMed1986

[Preliminary results in favor of the existence of a major surface antigen, specific for Leishmania braziliensis braziliensis].

The comparative surface antigen study of 10 bolivian strains and 1 brazilian reference strain from L. b. braziliensis sub-species shows an important homogeneity within this group. All the strains tested so far present similar antigenic patterns with a major antigen at 72 kD. On the contrary, the comparative analysis of surface antigens of L. b. braziliensis with those of L. b. guyanensis, L. b. panamensis, L. mexicana amazonensis and L. donovani chagasi shows a large antigenic heterogeneity between the Leishmania sub-species and species we studied. The 72 kD antigen was only detected on L. b. braziliensis surface.

Animals↗
PubMed1985

[Light chain disease with terminal myocardiopathy].

The authors report a case of a 35 year old man with of congestive cardiac failure. Echocardiography showed diffuse hypokinetic wall motion with moderate parietal hypertrophy without dilatation. Post-mortem examination showed intramyocardial deposits of light chains identical to those observed in "in vivo" renal and liver biopsies. This rarely described disease has a poor prognosis. It is characterised by polyvisceral infiltrations of light chain monoclonal immunoglobulins. Renal disease is usually the main problem progressing rapidly to renal failure. Of the extra renal localisations, cardiac involvement would appear to be common and preoccupying in itself. Monoclonal plasmocytic proliferation is observed in all cases, the majority but not all being malignant (myeloma). The incidence of this condition is probably underestimated and may pass undetected if immunofluorescent techniques are not used. Myelomatous light chain cardiac disease could therefore be more common than amyloidosis with which it presents a number of common features.

Adult↗
PubMed1978

Nuclear scattering radiography of the spine and sphenoid bone.

Nuclear scattering radiographs of a portion of a spine and a sphenoid bone have been obtained using a 1 GeV proton beam. The ability of the method to yield three-dimensional representations is illustrated by three series of adjacent pictures corresponding to the three orthogonal planes (elementary volume: 5.2 mm3 and 0.9 mm3). The sensitivity of the method is discussed. Nuclear scattering radiographs are compared with ones obtained by conventional X-ray tomography and computed tomography. Nuclear scattering radiography also may be used to analyze the partition of hydrogen within the tissures. Hydrogen radiographs obtained in this way are shown.

Elementary Particles↗