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Biomedical subjects

A Caille

Publications and source records attributed to A Caille.

At least 19 recordsLinked to original sources
PubMed2001

Solution structures of the antifungal heliomicin and a selected variant with both antibacterial and antifungal activities.

In response to an experimental infection, the lepidopteran Heliothis virescens produces an antifungal protein named heliomicin. Heliomicin displays sequence similarities with antifungal plant defensins and antibacterial or antifungal insect defensins. To gain information about the structural elements required for either antifungal or antibacterial activity, heliomicin and selected point-mutated variants were expressed in yeast as fusion proteins. The effects of mutations, defined by comparing the primary structure of heliomicin with the sequences of members of the insect defensin family, were analyzed using antibacterial and antifungal assays. One of the variants shows significant activity against Gram-positive bacteria while remaining efficient against fungi. The three-dimensional structures of this variant and of the wild-type protein were determined by two-dimensional (1)H NMR to establish a correlation between structure and antibacterial or antifungal activity. Wild-type and mutated heliomicins adopt a similar scaffold, including the so-called cysteine-stabilized alphabeta motif. A comparison of their structures with other defensin-type molecules indicates that common hydrophobic characteristics can be assigned to all the antifungal proteins. A comparative analysis of various structural features of heliomicin mutant and of antibacterial defensins enables common properties to be assessed, which will help to design new mutants with increased antibacterial activity.

Amino Acid Sequence↗
PubMed2000

The wide binding properties of a wheat nonspecific lipid transfer protein. Solution structure of a complex with prostaglandin B2.

The 3D solution structure of wheat nonspecific lipid transfer protein (ns-LTP) complexed with prostaglandin B2, a lipid with both vinyl and hydroxylated groups, has been determined by 1H 2D NMR. The global fold of the protein is close to the previously published structures of wheat, maize, barley and rice ns-LTPs. The ligand is almost completely embedded in the hydrophobic core of the protein. Structure comparisons of free and bound wheat ns-LTP reveal that the binding of prostaglandin B2 hardly affects the global fold of the protein. The structural data on this unusual complex are discussed and compared with other known ns-LTP lipid-complexes.

Binding Sites↗
PubMed1998

Erythema nodosum and associated diseases. A study of 129 cases.

BACKGROUND: Erythema nodosum (EN) is associated with many infectious diseases. The purpose of this study was to evaluate the relative prevalence of associated diseases in a large series of EN, and to review the previously described causes of EN. MATERIALS AND METHODS: A total of 157 inpatients with a diagnosis of EN made in Strasbourg, France between 1960 and 1995 were studied retrospectively, but only 129 patients with confirmed EN were evaluated. A biopsy was taken in 30 patients with atypical clinical symptoms. Chest radiography, blood cell count, throat swab, and anti-streptolysin dosage were performed systematically. Viral investigations and serodiagnoses for various bacterial infections were carried out in approximately half of the patients. All investigations were analyzed retrospectively and compared with the world literature. RESULTS: The female: male ratio was 5 : 1 and the mean age was 31 years. We found 28% confirmed streptococcal infections, 11% sarcoidosis, 1.5% enteropathies, 1.5% Chlamydia infections, 0.8% Mycoplasma infections, 0.8% Yersinia infections, 0.8% hepatitis B, and 0.8% tuberculosis (one case). The causative factor could not be determined in 55% of patients. CONCLUSIONS: Our data confirm the predominance of streptococcal infections and sarcoidosis among patients with EN. Tuberculosis has virtually disappeared, since the last case was observed in 1962. Various viral or bacterial diseases are rarely associated with EN, but all patients were not thoroughly investigated. A large and prospective study should be performed in order to determine the true prevalence of associated diseases in EN. In the absence of specific symptoms, exhaustive investigations are not cost-effective.

Adolescent↗
PubMed1997

1H NMR and fluorescence studies of the complexation of DMPG by wheat non-specific lipid transfer protein. Global fold of the complex.

Plant non-specific lipid transfer proteins (LTPs) are proteins which transfer lipids between membranes in vitro and are believed to be involved in the transport of cutin monomers to the cuticle layer in vivo or in the plant defence against phytopathogens. The complexation of DMPG, a diacyl phospholipid, by wheat ns-LTP, a protein extracted from wheat seeds, was followed by 1H NMR and fluorescence spectroscopy. The global fold of the protein was calculated using the DIANA software package from a list of 968 distance constraints. The internal cavity volume, a feature common to all known ns-LTP structures, was estimated to be 750 A3 using the 'CAVITE' program. This model of the complex was obtained by inserting a lipid molecule in the cavity and was energy minimized. The study showed that the protein fold described for the free form was only weakly affected by the insertion of the bulky lipid. Observation of some intermolecular NOEs between the protein and the lipid glycerol moiety revealed that the cavity entrance was located between residues His35 and Arg44. The resulting solution structure was compared to the crystal structure of the maize ns-LTP/palmitate complex.

Arginine↗
PubMed1996

[Osteomalacia cured by resection of cutaneous neurinoma].

INTRODUCTION: Regression of osteomalacia after exeresis of a skin tumor is unusual. CASE REPORT: A 62-year-old man had suffered from bone and joint symptoms for several years due to osteomalacia which was confirmed both biologically and histologically. The patient also had a plantar neurinoma. After exeresis of the tumor the biological results returned to normal levels within one week followed by regression of the clinical signs of osteomalacia. DISCUSSION: The neurinoma in this patient was apparently the cause of osteomalacia, since signs of the disease disappeared after exeresis. To date, three cases of neurinoma associated with osteomalacia have been published, including a single case with skin localization. The tumor would secrete a substance which inhibits the synthesis of vitamin D and enhances phosphorus excretion.

Foot Dermatoses↗
PubMed1994

Three-dimensional structure in solution of a wheat lipid-transfer protein from multidimensional 1H-NMR data. A new folding for lipid carriers.

Two-dimensional and three-dimensional 1H-NMR experimental data [Simorre, J. P., Caille, A., Marion, D., Marion, D. & Ptak, M. (1991) Biochemistry 30, 11600-11608] were used to build models of the three-dimensional structure of a non-specific wheat lipid-transfer protein (LTP) by using distance geometry, simulated annealing, energy minimization and molecular dynamics techniques. A first set of 881 distance constraints derived from NOE cross-peak intensities was used to generate 74 initial structures. One family of topological mirror images of the protein structure was eliminated by considering helical secondary-structure organization and steric requirements. Back calculations of NOE intensities led us to introduce 535 additional distance constraints. Finally, 21 structures were selected as representative of the structure of the protein. The polypeptide backbone folds into a simple and original right-handed winding. It is composed of a bundle of four helices linked by flexible loops, which is packed against a C-terminal fragment forming a non-standard saxophone-like shape. The folded protein is stabilized by hydrophobic interactions and the four disulfide bridges combined by pairs on each side of the protein. An hydrophobic cleft, formed by residues located in the second half of the protein could be a potential site for the binding of lipids.

Amino Acid Sequence↗
PubMed1992

Effect of different culture techniques used to induce capacitation on the chromatin stability of human sperm.

To validate an in-vitro bioassay for assessing chromatin stability of human sperm, 38 semen samples from infertile men were studied using sodium dodecyl sulphate, an anionic detergent which disorganizes only the cytoplasmic membrane. Assay sensitivity was 50 sperm, whilst the within- and between-assay variation, and the between-observer variation were found to be within the accepted range for this type of bioassay. The influence of different in-vitro treatments currently used in some clinical assisted fertilization programmes was evaluated: a destabilizing effect occurred in Grade I (stable) and Grade III (swollen) sperm. In the former, all treatments reduced stable sperm; in the latter, a significant (P less than 0.001) increase in swollen sperm was shown with two methods that used Ham's F-10 as culture medium. Different chromatin patterns found in the treated sperm suggest the possibility that the recovered samples could be modified compared to their status at the time of isolation.

Biological Assay↗
PubMed1992

Sperm peritoneal recovery in infertile couples with male factors.

Several studies (1-3) dealing with the presence of spermatozoa in preovulatory peritoneal liquid have shown a low correlation with the situation prevailing in the uterine cervix. Although all previous studies have worked with normospermic populations, we aimed at answering whether alterations of seminal variables are associated with alterations in transportation along the feminine tract. Different sperm migrations (in concentration and motility) were found, depending on the number of seminal variables altered.

Female↗
PubMed1991

Two- and three-dimensional 1H NMR studies of a wheat phospholipid transfer protein: sequential resonance assignments and secondary structure.

Two- and three-dimensional 1H NMR experiments have been used to sequentially assign nearly all proton resonances of the 90 residues of wheat phospholipid transfer protein. Only a few side-chain protons were not identified because of degeneracy or overlapping. The identification of spin systems and the sequential assignment were made at the same time by combining the data of the two- and three-dimensional experiments. The classical two-dimensional COSY, HOHAHA, and NOESY experiments benefit from both good resolution and high sensitivity, allowing the detection of long-range dipolar connectivities. The three-dimensional HOHAHA-NOESY experiment offers the advantage of a faster and unambiguous assignment. As a matter of fact, homonuclear three-dimensional NMR spectroscopy proved to be a very efficient method for resonance assignments of protein 1H NMR spectra which cannot be unraveled by 2D methods. An assignment strategy which overcomes most of the ambiguities has been proposed, in which each individual assignment toward the C-terminal end is supported by another in the opposite direction originating from a completely different part of the spectrum. Location of secondary structures of the phospholipid transfer protein was determined by using the method of analysis introduced here and was confirmed by 3J alpha NH coupling and NH exchange rates. Except for the C-terminal part, the polypeptide chain appears to be organized mainly as helical fragments connected by disulfide bridges. Further modeling will display the overall folding of the protein and should provide a better understanding of its interactions with lipids.

Amino Acid Sequence↗
PubMed1990

A 2D NMR study of the internal flexibility of the antifungal peptide stendomycin.

A 2-D 1H NMR study (NOESY, COSY, HOHAHA and ROESY experiments) of the antifungal peptide stendomycin is presented. The variation of the NOESY cross peak intensities is measured as a function of temperature in order to discriminate between constant and fluctuating interproton distances. It is shown that among 71 NOESY cross peaks, only 12 correspond to well defined interproton distances and their correlation time is determined. The other cross peaks cannot be translated accurately in terms of distances owing to internal molecular motions. (1H)-13C nOe measurements confirm the internal mobility of the molecule. Finally a flexibility map of stendomycin can be established.

Amino Acid Sequence↗
PubMed1987

Modelling and refinement of the conformation of mycosubtilin in solution from two-dimensional NMR data.

The conformation in solution of mycosubtilin, an antifungal lipopeptide [cyclo(L-Asn-D-Tyr-D-Asn-L-Gln-L-Pro-D-Asn-L-Ser-beta-amino acid)]has been probed by two-dimensional nuclear magnetic resonance and restrained energy minimization. Several structures have been proposed belonging to the same family with minor local variations related to different orientations of amide planes. The molecular topology was found to be completely different from that of iturin A, an analogue which exhibits quite different biological properties. The cyclic peptide of mycosubtilin is shown to be rather rigid in the region of L-proline and stabilized by C7 structures; in contrast, the neighbourhood of D-tyrosine-2 was found to be more flexible. The validity of our models is discussed first in terms of distance violation and second on the basis of reconstructed NOE spectroscopy maps. The different limitations towards higher-resolution structures are discussed.

Antifungal Agents↗
PubMed1978

Synthesis and beta-conformation of copolypeptides with alternating hydrophilic and hydrophobic residues.

Copolypeptides with alternating hydrophilic and hydrophobic residues were prepared, and their ability to form beta-structures in aqueous solutions was investigated by circular dichroism. Optically pure samples of poly (Lys-Leu-Lys-Leu) and poly (Leu-Glu-Leu-Glu), obtained via the 2-hydroxyphenyl esters, undergo a coil-to-beta transition in presence of salt. The beta-structures obtained under identical conditions with partially racemized samples of poly (Leu-Lys)Np and poly (Leu-Glu)Np, prepared by polycondensation of the corresponding dipeptide p-nitrophenyl esters, appear to be less regular. Non-alternating poly (Gly-Lys-Leu-Lys-Leu) does not form beta-structures in presence of NaCl as does alternating poly (Lys-Leu-Lys-Leu) indicating that the amino acid sequence can dramatically change the tendency to form beta-structures.

Amino Acid Sequence↗
PubMed1977

Reactivity of sulfhydryl group in peptides and poly-peptides with p-nitrophenylacetate. S to N acyl shift in cysteine.

The activity of poly (Cys-Ser-Phe-Glu-Glu) and related polypeptides as models of cysteine-proteases towards p-nitrophenylacetate was studied. The reaction leads to the formation of an S-acetylated form which proved to be quite stable, except at very high pH values. The presence of imidazole groups in the neighbourhood of sulfhydryl functions seems to result in an enhancement of the activity, which we attributed to a cooperative interaction. However, this interaction has no effect upon the S-deacylation rate. In the case of cysteine we found that the reaction with NPA occurred through a S to N acyl shift. Our results lead us to suggest that, unless convincing proofs of deacylation are given, the various models of cysteine-proteases studied so far do not behave as "true catalysts".

Acylation↗