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51.
Enhanced extraction of proteins using cholinium‐based ionic liquids as phase‐forming components of aqueous biphasic systems 下载免费PDF全文
Maria V. Quental Magda Caban Matheus M. Pereira Piotr Stepnowski João A. P. Coutinho Mara G. Freire 《Biotechnology journal》2015,10(9):1457-1466
Aqueous biphasic systems (ABS) composed of ionic liquids (ILs) are promising platforms for the extraction and purification of proteins. In this work, a series of alternative and biocompatible ABS composed of cholinium‐based ILs and polypropylene glycol were investigated. The respective ternary phase diagrams, tie‐lines, tie‐line lengths and critical points were determined at 25°C. The extraction performance of these systems for commercial bovine serum albumin (BSA) was then evaluated. The stability of BSA at the IL‐rich phase was ascertained by size exclusion high‐performance liquid chromatography and Fourier transform infrared spectroscopy. Appropriate ILs lead to the complete extraction of BSA for the IL‐rich phase, in a single step, while maintaining the protein's native conformation. Furthermore, to evaluate the performance of these systems when applied to real matrices, the extraction of BSA from bovine serum was additionally carried out, revealing that the complete extraction of BSA was maintained and achieved in a single step. The remarkable extraction efficiencies obtained are far superior to those observed with typical polymer‐based ABS. Therefore, the proposed ABS may be envisaged as a more effective and biocompatible approach for the separation and purification of other value‐added proteins. 相似文献
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53.
Zilca Campos Guilherme Mour?o Marcos Coutinho William E. Magnusson Balbina M. A. Soriano 《PloS one》2015,10(6)
We monitored the number of caiman (Caiman crocodilus yacare) nests in two ranches in the Brazilian Pantanal that cover an area of about 50.000 ha for 28 years (1987–2014). The number of nests was related to combinations of rainfall, water level, and number of days with temperature below 20°C, depending on the area. Most of the variation in number of nests could not be predicted by the environmental variables, but could be represented mathematically by a sine wave. We were not able to identify any external driver and suspect that the regular fluctuations may have resulted from an intrinsic population process. Presently, ranches are used as management units under the legislation for ranching Pantanal caimans. However, although some breeding females were recaptured in the area after periods of up to 21 years, most were not recaptured near nests or in general surveys of the area, suggesting that females are not strongly philopatric and that ranches do not represent isolated demographic units. 相似文献
54.
Eduardo Vilanova Cristiano Coutinho Guilherme Maia Paulo A. S. Mourão 《Cell and tissue research》2010,340(3):523-531
Marine sponges (Porifera) display an ancestral type of cell-cell adhesion, based on carbohydrate-carbohydrate interaction.
The aim of the present work was to investigate further details of this adhesion by using, as a model, the in vitro aggregation
of dissociated sponge cells. Our results showed the participation of sulfated polysaccharides in this cell-cell interaction,
as based on the following observations: (1) a variety of sponge cells contained similar sulfated polysaccharides as surface-associated
molecules and as intracellular inclusions; (2) 35S-sulfate metabolic labeling of dissociated sponge cells revealed that the majority (two thirds) of the total sulfated polysaccharide
occurred as a cell-surface-associated molecule; (3) the aggregation process of dissociated sponge cells demanded the active
de novo synthesis of sulfated polysaccharides, which ceased as cell aggregation reached a plateau; (4) the typical well-organized
aggregates of sponge cells, known as primmorphs, contained three cell types showing sulfated polysaccharides on their cell
surface; (5) collagen fibrils were also produced by the primmorphs in order to fill the extracellular spaces of their inner
portion and the external layer surrounding their entire surface. Our data have thus clarified the relevance of sulfated polysaccharides
in this system of in vitro sponge cell aggregation. The molecular basis of this system has practical relevance, since the
culture of sponge cells is necessary for the production of molecules with biotechnological applications. 相似文献
55.
Vijay M. Khedkar Premlata K. Ambre Jitender Verma Mushtaque S. Shaikh Raghuvir R. S. Pissurlenkar Evans C. Coutinho 《Journal of molecular modeling》2010,16(7):1251-1268
HIV-1 protease is an obligatory enzyme in the replication process of the HIV virus. The abundance of structural information
on HIV-1PR has made the enzyme an attractive target for computer-aided drug design strategies. The daunting ability of the
virus to rapidly generate resistant mutants suggests that there is an ongoing need for new HIV-1PR inhibitors with better
efficacy profiles and reduced toxicity. In the present investigation, molecular modeling studies were performed on a series
of 54 cyclic urea analogs with symmetric P2/P2′ substituents. The binding modes of these inhibitors were determined by docking.
The docking results also provided a reliable conformational superimposition scheme for the 3D-QSAR studies. To gain insight
into the steric, electrostatic, hydrophobic and hydrogen-bonding properties of these molecules and their influence on the
inhibitory activity, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA)
were performed. Two different alignment schemes viz. receptor-based and atom-fit alignment, were used in this study to build the QSAR models. The derived 3D-QSAR models were found to be robust with statistically
significant r
2
and r
2
pred
values and have led to the identification of regions important for steric, hydrophobic and electronic interactions. The predictive
ability of the models was assessed on a set of molecules that were not included in the training set. Superimposition of the
3D-contour maps generated from these models onto the active site of enzyme provided additional insight into the structural
requirements of these inhibitors. The CoMFA and CoMSIA models were used to design some new inhibitors with improved binding
affinity. Pharmacokinetic and toxicity predictions were also carried out for these molecules to gauge their ADME and safety
profile. The computational results may open up new avenues for synthesis of potent HIV-1 protease inhibitors. 相似文献
56.
Jean‐Charles Blouzard Pedro M. Coutinho Henri‐Pierre Fierobe Bernard Henrissat Sabrina Lignon Chantal Tardif Sandrine Pagès Pascale de Philip 《Proteomics》2010,10(3):541-554
Clostridium cellulolyticum is a model mesophilic anaerobic bacterium that efficiently degrades plant cell walls. The recent genome release offers the opportunity to analyse its complete degradation system. A total of 148 putative carbohydrate‐active enzymes were identified, and their modular structures and activities were predicted. Among them, 62 dockerin‐containing proteins bear catalytic modules from numerous carbohydrate‐active enzymes' families and whose diversity reflects the chemical and structural complexity of the plant carbohydrate. The composition of the cellulosomes produced by C. cellulolyticum upon growth on different substrates (cellulose, xylan, and wheat straw) was investigated by LC MS/MS. The majority of the proteins encoded by the cip‐cel operon, essential for cellulose degradation, were detected in all cellulosome preparations. In the presence of wheat straw, the natural and most complex of the substrates studied, additional proteins predicted to be involved in hemicellulose degradation were produced. A 32‐kb gene cluster encodes the majority of these proteins, all harbouring carbohydrate‐binding module 6 or carbohydrate‐binding module 22 xylan‐binding modules along dockerins. This newly identified xyl‐doc gene cluster, specialised in hemicellulose degradation, comes in addition of the cip‐cel operon for plant cell wall degradation. Hydrolysis efficiencies determined on the different substrates corroborates the finding that cellulosome composition is adapted to the growth substrate. 相似文献
57.
58.
The Lotka-Volterra competition model was used to represent the interaction between Laurencia obtusa and Hypnea spinella. A new model that considers effects of competition on algal carrying capacity is suggested. To test the models, data from field experiments conducted in an intertidal region at Cabo Frio Island, Rio de Janeiro, Brazil, were used. Both models showed that Hypnea was a stronger competitor than Laurencia. The model of interaction through the carrying capacity showed a stable coexistence between the algal populations and better represented the experimental data. 相似文献
59.
Monteiro-Vitorello CB Camargo LE Van Sluys MA Kitajima JP Truffi D do Amaral AM Harakava R de Oliveira JC Wood D de Oliveira MC Miyaki C Takita MA da Silva AC Furlan LR Carraro DM Camarotte G Almeida NF Carrer H Coutinho LL El-Dorry HA Ferro MI Gagliardi PR Giglioti E Goldman MH Goldman GH Kimura ET Ferro ES Kuramae EE Lemos EG Lemos MV Mauro SM Machado MA Marino CL Menck CF Nunes LR Oliveira RC Pereira GG Siqueira W de Souza AA Tsai SM Zanca AS Simpson AJ Brumbley SM Setúbal JC 《Molecular plant-microbe interactions : MPMI》2004,17(8):827-836
The genome sequence of Leifsonia xyli subsp. xyli, which causes ratoon stunting disease and affects sugarcane worldwide, was determined. The single circular chromosome of Leifsonia xyli subsp. xyli CTCB07 was 2.6 Mb in length with a GC content of 68% and 2,044 predicted open reading frames. The analysis also revealed 307 predicted pseudogenes, which is more than any bacterial plant pathogen sequenced to date. Many of these pseudogenes, if functional, would likely be involved in the degradation of plant heteropolysaccharides, uptake of free sugars, and synthesis of amino acids. Although L. xyli subsp. xyli has only been identified colonizing the xylem vessels of sugarcane, the numbers of predicted regulatory genes and sugar transporters are similar to those in free-living organisms. Some of the predicted pathogenicity genes appear to have been acquired by lateral transfer and include genes for cellulase, pectinase, wilt-inducing protein, lysozyme, and desaturase. The presence of the latter may contribute to stunting, since it is likely involved in the synthesis of abscisic acid, a hormone that arrests growth. Our findings are consistent with the nutritionally fastidious behavior exhibited by L. xyli subsp. xyli and suggest an ongoing adaptation to the restricted ecological niche it inhabits. 相似文献
60.
EFFECTS OF HUMAN ACTIVITIES ON STRUCTURE AND COMPOSITION OF WOODY SPECIES OF THE NOKREK BIOSPHERE RESERVE OF MEGHALAYA,NORTHEAST INDIA 下载免费PDF全文
Aims Our study was conducted in the Nokrek Biosphere Reserve (NBR) in the Garo hills districts of Meghalaya, Northeast India. Our aim was to assess the effects of human activities on plant diversity,population structure and regeneration.Methods We selected a representative 1.2 hm2 stand in both the core and buffer zones of NBR. Structure and composition were determined by randomly sampling square quadrats, population structure was assessed by determining age structure, and regeneration was assessed by measuring densities of seedling, sapling and adult trees.Important findings More woody species were recorded from the core zone than the buffer zone (87 vs. 81 species), and there were a large number of tropical, temperate, and Sino-Himalayan, Burma-Malaysian and Malayan elements, primitive families and primitive genera. The trees were distributed in three distinct strata,canopy, subcanopy and sapling. Subcanopy and sapling layers had the highest species richness (81% -88% ). Lauraceae and Euphorbiaceae were the dominant families in terms of the number of species, and a large number of families were represented by single species. Most woody species (57 % - 79 % ) were contagiously distributed and had low frequency ( < 20% ). Although stand density was high in the buffer zone, its basal area was low compared to the stand in the core zone. Low similarity and high β-diversity indicate marked differences in species composition of the stands. Shannon diversity index was high in both the stands, while Simpson dominance index was low. The diameter-class distribution for dominant species revealed that the most had a large number of young individuals in their populations. Preponderance of tree seedlings, followed by a steep decline in population density of saplings and adult trees, indicated that the seedling to sapling stage was the most critical in the life cycle of the tree populations. Most species (42 % - 48 % ) had no regeneration,25 % - 35 % had good/fair regeneration, and the rest had poor regeneration or reoccurred as immigrants. 相似文献