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31.
Immacolata Del Giudice Danila Limauro Emilia Pedone Simonetta Bartolucci Gabriella Fiorentino 《Biochimica et Biophysica Acta - Proteins and Proteomics》2013,1834(10):2071-2079
Microorganisms living in arsenic-rich geothermal environments act on arsenic with different biochemical strategies, but the molecular mechanisms responsible for the resistance to the harmful effects of the metalloid have only partially been examined. In this study, we investigated the mechanisms of arsenic resistance in the thermophilic bacterium Thermus thermophilus HB27. This strain, originally isolated from a Japanese hot spring, exhibited tolerance to concentrations of arsenate and arsenite up to 20 mM and 15 mM, respectively; it owns in its genome a putative chromosomal arsenate reductase (TtarsC) gene encoding a protein homologous to the one well characterized from the plasmid pI258 of the Gram + bacterium Staphylococcus aureus. Differently from the majority of microorganisms, TtarsC is part of an operon including genes not related to arsenic resistance; qRT-PCR showed that its expression was four-fold increased when arsenate was added to the growth medium. The gene cloning and expression in Escherichia coli, followed by purification of the recombinant protein, proved that TtArsC was indeed a thioredoxin-coupled arsenate reductase with a kcat/KM value of 1.2 × 104 M− 1 s− 1. It also exhibited weak phosphatase activity with a kcat/KM value of 2.7 × 10− 4 M− 1 s− 1. The catalytic role of the first cysteine (Cys7) was ascertained by site-directed mutagenesis. These results identify TtArsC as an important component in the arsenic resistance in T. thermophilus giving the first structural–functional characterization of a thermophilic arsenate reductase. 相似文献
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Aureo Banhos Bruno L. Fontes Débora Regina Yogui Mario Henrique Alves Natália Carneiro Ardente Renata Valls Lucas Mendes Barreto Lucas Damásio Átilla Colombo Ferreguetti Andréa Siqueira Carvalho Vitor Roberto Schettino Alexandre Rosa dos Santos Helena Godoy Bergallo Ana Carolina Srbek-Araujo Emilia Patrícia Medici Ariel Canena Arnaud L.J. Desbiez 《Biotropica》2020,52(3):421-426
We report 24 records of giant armadillo roadkill on Brazilian highways in the Cerrado, Pantanal and Amazon biomes illustrating that highways are a threat to this species. However, we also documented the species using underpasses, demonstrating that these structures could help to reduce the risk of roadkill for giant armadillos. 相似文献
34.
In this study, by applying a combined approach of NMR measurements and molecular modelling, the conformations and the interactions with membrane-like environment of five arginine vasopressin (AVP) or oxytocin (OT) analogues modified with Cα-disubstituted cis-1-amino-4-phenylcyclohexane-1-carboxylic acid in position 2 have been determined. In addition, the AVP analogues were prepared in N-acylated forms with various bulky acyl groups. All of the peptides studied interacted with the mixed dodecylphosphocholine:sodium dodecyl sulphate micelle, providing a model of biological membrane. A different polarities of the AVP- and OT-like peptides resulted in their different position relative to the micelle surface. Thus, the arrangement of the former was nearly perpendicular, whereas the latter was rather parallel to the micelle's surface. Moreover, the results of our studies have shown that the binding sites for antagonists may be overlapped with that for agonists, as well as it may be quite different. Nevertheless, the aromatic–aromatic contacts represent the most important interactions for antagonists, whereas the hydrophilic interactions seem to be crucial for agonists. 相似文献
35.
Maria Victoria Tuttolomondo Maria Emilia Villanueva Gisela Solange Alvarez Martín Federico Desimone Luis Eduardo Díaz 《Biotechnology letters》2013,35(10):1571-1577
The synthesis of monodispersed magnetic silica nanoparticles (MSN) is described using a water-in-oil reverse microemulsion system that does not require the use of co-surfactants. Sodium silicate, Tween 20 as a neutral surfactant and 1-butanol as the organic phase were used. There are several advantages of the proposed method including a saturation magnetization value of 10 emu/g for the particles obtained, uniformity of size and that they are easily functionalized to bind urease covalently. Moreover, the intra-day, inter-day and long-term stability results confirm that the procedure was successful and the enzyme-linked MSNs were stable over repeated uses and storage retaining more than 75 % activity after 4 months. 相似文献
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An analysis was made of the protein content of pollen loads produced by the bees in a hive situated in Viana do Bolo (Ourense, north-west Spain), to establish whether or not the relative quantity of protein in the pollen of each plant species influences the preference made by the bee of the flowers that supply pollen to the hive. This analysis was performed on all types of pollen that formed more than 5% of the pollen spectrum. Pollen load samples were collected directly from the hive from March to September. Pollen loads were separated by colour, and their specific homogeneity was confirmed microscopically. The Bradford method has been used for protein extraction and spectrophotometry was used for the determination of protein content. The results show that the different pollen loads have high protein content. Pollen of the plant species that reached relatively higher percentages in the pollen spectrum are also those that have the highest protein content. These were Cytisus scoparius type, uncultivated Poaceae, Quercus robur type, Sanguisorba minor, Salix fragilis and Spergularia rubra type. The pollen of the systematic units, which had pollen loads that could be identified at the level of species, maintained a constant value of protein content independently of the date the samples were obtained. The pollen of the systematic units, which had pollen loads that could be identified at the level of pollen type, has varied in protein content in the analyses performed on samples obtained on different dates. This result is due to the fact that the different species that integrate the pollen type flower on different dates, and thus have a pollenkitt with different characteristics. 相似文献
38.
The pollen content of eleven honey samples from ten different apiaries in the Baixa Limia – Serra do Xurés Nature Reserve and other honey commercialised by the cooperative as “Mel do Xurés” (north‐west Spain) was subjected to quantitative and qualitative melissopalynological analysis. The quantitative analysis found that ten samples belonged to Maurizio's Class III and one to Class IV. According to the qualitative analysis, four samples were classified as unifloral honey with Erica, four samples as multifloral honey with Erica pollen as the principal component and three samples as multifloral honey with Cytisus‐type pollen and Erica as the principal component pollen. The pollen spectra differ between the diverse honeys analysed, with a common denominator being Erica and Cytisus‐type pollen being abundant in all. For the rest of the samples, the pollen spectra were mainly the same, but with different relative percentages among secondary elements. Thus, either as a secondary or an important element, 91% of the honeys contained Quercus, 82% Castanea sativa Miller, 45% Rubus, 36% Cistus and 27% Lithodora prostrate (Loisel) Griseb,. In particular, we record for the first time the presence of Ribes and Ilex aquifolium L. pollen in Spanish honeys as an important minor or minor pollen component. 相似文献
39.
Luciano Pirone Luigi Vitagliano Sonia Di Gaetano Emilia Pedone 《Journal of molecular recognition : JMR》2013,26(10):488-495
Recent investigations have shown that members of the KCTD family play important roles in fundamental biological processes. Despite their roles, very limited information is available on their structures and molecular organization. By combining different experimental and theoretical techniques, we have here characterized the two folded domains of KCTD12, an integral component and modulator of the GABAB2 receptor. Secondary prediction methods and CD spectroscopy have shown that the N‐terminal domain KCTD12BTB assumes an α/β structure, whereas the C‐terminal domain KCTD12H1 is predominantly characterized by a β‐structure. Binding assays indicate that the two domains independently expressed show a good affinity for each other. This suggests that the overall protein is likely endowed with a rather compact structure with two interacting structured domains joint by a long disordered region. Notably, both KCTD12BTB and KCTD12H1 are tetrameric when individually expressed. This finding could modify the traditional view that ascribes only to POZ/BTB domain a specific oligomerization role. The first quantification of the affinity of KCTD12POZ/BTB for the C‐terminal region of GABAB2 shows that it falls in the low micromolar range. Interestingly, we also demonstrate that a GABAB2‐related peptide is able to bind KCTD12BTB with a very high affinity. This peptide may represent a useful tool for modulating KCTD12/GABAB2 interaction in vitro and may also constitute the starting point for the development of peptidomimetic compounds with a potential for therapeutic applications. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
40.
David Mansouri Donald C. McMillan Yasmin Grant Emilia M. Crighton Paul G. Horgan 《PloS one》2013,8(6)