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1.
Sarrah M'Barek Ziad Fajloun Sandrine Cestle Christiane Devaux Pascal Mansuelle Amor Mosbah Besma Jouirou Massimo Mantegazza Jurphaas van Rietschoten Mohamed El Ayeb Herv Rochat Jean‐Marc Sabatier Francois Sampieri 《Journal of peptide science》2004,10(11):666-677
Aah I is a 63-residue alpha-toxin isolated from the venom of the Buthidae scorpion Androctonus australis hector, which is considered to be the most dangerous species. We report here the first chemical synthesis of Aah I by the solid-phase method, using a Fmoc strategy. The synthetic toxin I (sAah I) was renatured in DMSO-Tris buffer, purified and subjected to thorough analysis and comparison with the natural toxin. The sAah I showed physico-chemical (CD spectrum, molecular mass, HPLC elution), biochemical (amino-acid composition, sequence), immunochemical and pharmacological properties similar to those of the natural toxin. The synthetic toxin was recognized by a conformation-dependent monoclonal anti-Aah I antibody, with an IC50 value close to that for the natural toxin. Following intracerebroventricular injection, the synthetic and the natural toxins were similarly lethal to mice. In voltage-clamp experiments, Na(v) 1.2 sodium channel inactivation was inhibited by the application of sAah I or of the natural toxin in a similar way. This work describes a simple protocol for the chemical synthesis of a scorpion alpha-toxin, making it possible to produce structural analogues in time. 相似文献
2.
Claudia C. Cornilescu Gabriel Cornilescu Hongyu Rao Sarah F. Porter Marco Tonelli Michele L. DeRider John L. Markley Fariba M. Assadi‐Porter 《Proteins》2013,81(6):919-925
The sweet protein brazzein, a member of the Csβα fold family, contains four disulfide bonds that lend a high degree of thermal and pH stability to its structure. Nevertheless, a variable temperature study has revealed that the protein undergoes a local, reversible conformational change between 37 and 3°C with a midpoint about 27°C that changes the orientations and side‐chain hydrogen bond partners of Tyr8 and Tyr11. To test the functional significance of this effect, we used NMR saturation transfer to investigate the interaction between brazzein and the amino terminal domain of the sweet receptor subunit T1R2; the results showed a stronger interaction at 7°C than at 37°C. Thus the low temperature conformation, which alters the orientations of two loops known to be critical for the sweetness of brazzein, may represent the bound state of brazzein in the complex with the human sweet receptor. Proteins 2013; © 2012 Wiley Periodicals, Inc. 相似文献
3.
Winter pruning is a cultural practice used to modify vegetative growth, which is likely to affect the development of pests. However, it has been poorly defined as a cultural method for diminishing the population levels of the pomegranate aphid Aphis punicae (Hemiptera, Aphididae) in pomegranate orchards. This study aimed to evaluate the impact of winter pruning of pomegranate on A. punicae population and their natural enemies. The results showed that winter pruning significantly decreased the population of A. punicae (p < 0.05) in pomegranate. Also, number of natural enemies decreased in pomegranate trees after winter pruning. This technical practice affects the number of winged and wingless individuals, the mean relative growth rate, the specific age of the population and the infestation rate. Winter pruning for A. punicae control in pomegranate orchards is highly recommended. 相似文献
4.
Ameur Cherif Besma Ettoumi Afef Najjari Noura Raddadi Abdellatif Boudabous 《Annals of microbiology》2007,57(1):21-27
The genomic diversity and relationship among 61Bacillus thuringiensis andBacillus cereus reference strains were investigated by electrophoretic analysis of esterase enzymes on native polyacrylamide gel. Polymorphism of the esterolytic bands revealed seven esterases, designed as Est A to Est G in order of decreasing anodal migration. Each esterase showed two to three mobility variants that assigned the analysed strains into 35 electrophoretic types (ETs). This high diversity allowed the identification of several serovar or strain-specific ETs. Cluster analysis of ETs showed three major groups in which the strains belonging to the serovartolworthi were the most distant. The ETs distribution showed thatB. thuringiensis andB. cereus are intermingled in the dendrogram with the resolution of some common serovars ofB. thuringiensis in tight phylogenetic lineages. These results indicate that the esterase enzyme electrophoresis, applied as a sole typing method for the closely related speciesB. thuringiensis andB. cereus is suitable to highlight the intraspecific genetic diversity. 相似文献
5.
Besma Sghaier-Hammami Jesús V. Jorrín-Novo Radhia Gargouri-Bouzid Noureddine Drira 《Phytochemistry》2010,71(11-12):1223-1236
Various supplements (abscisic acid (ABA) or sucrose) were added to the initial embryo culture medium (M3) with the aim of improving the vigour of vitroplants deriving from date palm somatic embryogenesis. ABA (20 and 40 μM) and sucrose (90 g/l) applied for 4 and 2 weeks respectively increased embryo thickness, with no apparent difference in length. ABA (5–40 μM) increased embryo proliferation rate. Somatic embryos maintained in modified M3 (M3 supplemented with ABA and an increased sucrose concentration) contained a higher amount of protein than those maintained in initial M3 (no ABA, 30 g/l of sucrose), with a 1.5–1.7-fold increase depending on the compound and concentration assayed. The 1-D and 2-DE protein profiles showed qualitative and quantitative differences between the somatic embryos cultured in initial M3 (control) and in modified M3. Statistical analysis of spot intensity was performed by principal component analysis, yielding two accurate groups of samples and determining the most discriminating spots. Samples were also clustered using Euclidean distance with an average linkage algorithm. Thirty-four variable spots were identified using mass spectrometry analysis. Identified proteins were classified into the following functional categories: energy metabolism (five proteins); protein translation, folding and degradation (9); redox maintenance (5); cytoskeleton (3); storage protein (2); and with no assigned function as (10). While “up-regulation” of stress-related proteins and “down-regulation” of energy metabolism proteins were observed in somatic embryos matured in M3 supplemented with ABA, storage proteins (legumin) were “up-regulated” in somatic embryos matured in M3 supplemented with increased sucrose. 相似文献
6.
Kallmann syndrome is a genetically heterogeneous developmental disease characterised by a partial or complete lack of olfactory
bulb development. Two genes underlying this disease have so far been identified: the KAL-1 gene, which encodes anosmin-1, an extracellular matrix protein that promotes axonal guidance and branch formation in vitro;
and KAL-2, which encodes the known FGFR1. The implication of FGFR1 and anosmin-1 in the same developmental disease led us to test whether
anosmin-1 and FGFR1 interact during the development of the olfactory system. In this paper, we showed that the two proteins
co-localise in the olfactory bulb during development in rat. Using cross-immunoprecipitation assays of olfactory bulb extracts,
we also demonstrated that anosmin-1 and FGFR1 are comprised within the same protein complex. Moreover, we show that anosmin-1
expression in CHO transfected cells increases FGFR1 accumulation, suggesting that anosmin-1 may act as a positive extracellular
regulator of FGFR1 signalling. Taken together, our findings strongly suggest that anosmin-1 is an essential component of a
FGFR1 pathway that plays a key role during olfactory bulb morphogenesis. 相似文献
7.
8.
Effect of various parameters such as size of inoculum, temperature, carbon source on decolorization of textile wastewater by Phanerochaete chrysosporium was investigated. Textile wastewater decolorization occurred during the primary phase of growth and secondary metabolism in carbon and nitrogen limited medium, respectively. It was found that glucose concentration up to 0.3 g/l has considerable effect on decolorisation rate. Further, it was also found that the concentration of the organic nitrogen of the effluent stream was sufficient to furnish the decolorisation process. It was observed that the inoculum size in this case within 10% increased the decolorisation rate rapidly. It was found that the temperature rise from 20 to 38 °C enhanced the rate of decolorization. The optimum temperature for decolorisation was found to be about 35 °C. Effect of pH from 2-4 on decolorization was also investigated. It is concluded that using Phanerochaete chrysosporium, decolorization of the azo dye containing effluent of the textile industry was achieved to about 96% within 28 h of operation. 相似文献
9.
An isoenzyme analysis was performed on 109 individuals from 11 populations of Juniperus excelsa complex collected from Iran. A total of 61 allozymes from five enzyme systems were scored. The mean numbers of bands per presumed isoenzyme, ranged from 2.07 to 3.23. The value of Euclidean distance ranged from 1.920 to 4.411. The average value of Shannon diversity index (H′) estimated for each population ranged from 0.317 in the population sampled from ‘Fasa’ to 1.053 in the population of ‘Golestan’, and the average H′ value for each enzyme system ranged from 0.031 (SOD-3) to 1.670 (PPO-1). To reveal the relationships among these populations, a cluster analysis based on Euclidean distances was performed. The results of the analysis suggest recognizing three taxa in the complex in Iran: Juniperus polycarpos subsp. polycarpos, Juniperus polycarpos subsp. turcomanica, and one cryptic species not recorded from Iran until now. Moreover, the analysis presented, does not confirm the occurrence of J. excelsa in Iran. 相似文献
10.
Amor BB Shaw SL Oldroyd GE Maillet F Penmetsa RV Cook D Long SR Dénarié J Gough C 《The Plant journal : for cell and molecular biology》2003,34(4):495-506
Establishment of the Rhizobium-legume symbiosis depends on a molecular dialogue, in which rhizobial nodulation (Nod) factors act as symbiotic signals, playing a key role in the control of specificity of infection and nodule formation. Using nodulation-defective (Nod-) mutants of Medicago truncatula to study the mechanisms controlling Nod factor perception and signalling, we have previously identified five genes that control components of a Nod factor-activated signal transduction pathway. Characterisation of a new M. truncatula Nod- mutant led to the identification of the Nod Factor Perception (NFP) locus. The nfp mutant has a novel phenotype among Nod- mutants of M. truncatula, as it does not respond to Nod factors by any of the responses tested. The nfp mutant thus shows no rapid calcium flux, the earliest detectable Nod factor response of wild-type plants, and no root hair deformation. The nfp mutant is also deficient in Nod factor-induced calcium spiking and early nodulin gene expression. While certain genes controlling Nod factor signal transduction also control the establishment of an arbuscular mycorrhizal symbiosis, the nfp mutant shows a wild-type mycorrhizal phenotype. These data indicate that the NFP locus controls an early step of Nod factor signal transduction, upstream of previously identified genes and specific to nodulation. 相似文献