Prediction-based protein engineering of domain I of Cry2A entomocidal toxin of Bacillus thuringiensis for the enhancement of toxicity against lepidopteran insects

Issues relating to sustenance of the usefulness of genetically modified first generation Bt crop plants in the farmer's field are of great concern for crop scientists. Additional biotechnological strategies need to be in place to safeguard the possibility for yield loss of Bt crop by other lepidopteran insects that are insensitive to the Cry1A toxin, and also against the possibility for emergence of resistant insects. In this respect, Cry2A toxin has figured as a prospective candidate to be the second toxin to offer the required protection along with Cry1A. In the present study, the entomocidal potency of Cry2A toxin was enhanced through knowledge-based protein engineering of the toxin molecule. Deletion of 42 amino acid residues from the N-terminal end of the peptide followed by the replacement of Lys residues by nonpolar amino acids in the putative transmembrane region including the introduction of Pro resulted in a 4.1-6.6-fold increase in the toxicity of the peptide against three major lepidopteran insect pests of crop plants.     

From rose petal to bone scaffolds: Using nature to fabricate osteon-like scaffolds for bone tissue engineering applications

In this study, rose petal was used to fabricate osteon-like scaffolds for bone tissue engineering applications. Rose petal was coupled with nanocrystalline forsterite colloid to mimic the lamellar structure of porous osteons. The microstructures on the surface of the petals were utilized as template for pores and lacuna spaces which are suitable for cell attachment. On the other hand, rolling the petals allowed us to form the osteon structure with haversian canal and lacuna spaces on the body of the samples. After trying different temperatures, the results showed that samples annealed at 1100 °C closely mimicked the lacuna spaces, haversian canal, and lamellar structures of osteons. These scaffolds had the pore diameter in the range of about 13–20 μm and presented good bioactivity and biocompatibility. It was found that red rose petal is a good candidate to be used as a template for designing scaffolds for bone tissue engineering applications.     

Process systems engineering: From Solvay to modern bio- and nanotechnology.: A history of development, successes and prospects for the future

The term Process Systems Engineering (PSE) is relatively recent. It was coined about 50 years ago at the outset of the modern era of computer-aided engineering. However, the engineering of processing systems is almost as old as the beginning of the chemical industry, around the first half of the 19th century. Initially, the practice of PSE was qualitative and informal, but as time went on it was formalized in progressively increasing degrees. Today, it is solidly founded on engineering sciences and an array of systems-theoretical methodologies and computer-aided tools. This paper is not a review of the theoretical and methodological contributions by various researchers in the area of PSE. Its primary objective is to provide an overview of the history of PSE, i.e. its origin and evolution; a brief illustration of its tremendous impact in the development of modern chemical industry; its state at the turn of the 21st century; and an outline of the role it can play in addressing the societal problems that we face today such as; securing sustainable production of energy, chemicals and materials for the human wellbeing, alternative energy sources, and improving the quality of life and of our living environment. PSE has expanded significantly beyond its original scope, the continuous and batch chemical processes and their associated process engineering problems. Today, PSE activities encompass the creative design, operation, and control of: biological systems (prokaryotic and eukaryotic cells); complex networks of chemical reactions; free or guided self-assembly processes; micro- and nano-scale processes; and systems that integrate engineered processes with processes driven by humans, legal and regulatory institutions. Through its emphasis on synthesis problems, PSE provides the dialectic complement to the analytical bent of chemical engineering science, thus establishing the healthy tension between synthesis and analysis, the foundation of any thriving discipline. As a consequence, throughout this paper PSE emerges as the foundational underpinning of modern chemical engineering; the one that ensures the discipline's cohesiveness in the years to come.     

Towards an efficient process for small-scale, decentralized conversion of methane to synthesis gas: combined reactor engineering and catalyst synthesis

Anthropogenic methane emissions not only pose an increasing global problem but can also be seen as an untapped renewable resource for hydrogen or liquid fuel production. Utilization of this resource requires the development of efficient processes for small-scale, decentralized methane conversion. We see catalytic partial oxidation of methane to synthesis gas as an ideal candidate for such a process. In the present study, we investigate the effect of heat-integration, flow rate and catalyst stability on syngas yields over alumina-supported Pt and Rh catalysts in a reverse-flow reactor configuration. We furthermore demonstrate that novel high-temperature stable nanocomposite catalysts can dramatically lower the noble metal requirement for this reaction, improve catalyst stability and further increase synthesis gas yields. Finally, we demonstrate that the combination of the reverse-flow reactor with these nanocomposite catalysts exploits the efficiency of this reaction route very effectively while maintaining a simple and compact reactor design.     

From structural ceramics to 2D materials with multi-applications: A review on the development from MAX phases to MXenes

MAX phases (Ti3SiC2, Ti3AlC2, V2AlC, Ti4AlN3, etc.) are layered ternary carbides/nitrides, which are generally processed and researched as structure ceramics. S...     

From peptides to proteins: lessons from my years at the Centre for Protein Engineering

The MRC Centre for Protein Engineering (CPE) hosted and trained many scientists over the years. It is a unique research environment that shaped the career of many scientists in all aspects. These include research directions and methodologies, but even more important--issues such as how to approach scientific problems and how to manage a research team. Alan Fersht was the director of the CPE when I joined it as a postdoc in the year 2000. In the current article for the PEDS special CPE issue, I will review how my scientific research and my approach to science developed from the days I arrived to the CPE as a young peptide chemist and throughout the years I spent at the CPE, and how it shaped my current research interests and attitude. I will focus on two major fields: (i) Using peptides to study and modulate the structure and interactions of proteins; (ii) Using quantitative biophysical methods to study proteins and their interactions at the molecular level.     

Three highly odorous metabolites from an actinomycete: 2-Isopropyl-3-methoxy-pyrazine,methylisoborneol, and geosmin

The highly odorous metabolites isopropylmethoxypyrazine, methylisoborneol, and geosmin were identified from aStreptomyces sp. Their role in the odor pollution of water is discussed. 2-Isopropyl-3-methoxypyrazine has not been reported previously from actinomycetes.     

Probing small-molecule binding to cytochrome P450 2D6 and 2C9: An in silico protocol for generating toxicity alerts

Drug metabolism, toxicity, and their interaction profiles are major issues in the drug-discovery and lead-optimization processes. The cytochromes P450 (CYPs) 2D6 and 2C9 are enzymes involved in the oxidative metabolism of a majority of marketed drugs. Therefore, the prediction of the binding affinity towards CYP2D6 and CYP2C9 would be beneficial for identifying cytochrome-mediated adverse effects triggered by drugs or chemicals (e.g., toxic reactions, drug-drug, and food-drug interactions). By identifying the binding mode by using pharmacophore prealignment, automated flexible docking, and by quantifying the binding affinity by multidimensional QSAR (mQSAR), we validated a model family of 56 compounds (46 training, 10 test) and 85 compounds (68 training, 17 test) for CYP2D6 and CYP2C9, respectively. The correlation with the experimental data (cross-validated r2=0.811 for CYP2D6 and 0.687 for CYP2C9) suggests that our approach is suited for predicting the binding affinity of compounds towards CYP2D6 and CYP2C9. The models were challenged by Y-scrambling and by testing an external dataset of binding compounds (15 compounds for CYP2D6 and 40 for CYP2C9). To assess the probability of false-positive predictions, datasets of nonbinders (64 compounds for CYP2D6 and 56 for CYP2C9) were tested by using the same protocol. The two validated mQSAR models were subsequently added to the VirtualToxLab (VTL, http://www.virtualtoxlab.org).     

Among the trends for a modern chemical engineering,the third paradigm: The time and length multiscale approach as an efficient tool for process intensification and product design and engineering

To respond to the changing needs of the chemical and related industries in order both to meet today's economy demands and to remain competitive in global trade, a modern chemical engineering is vital to satisfy both the market requirements for specific nano and microscale end-use properties of products, and the social and environmental constraints of industrial meso and macroscale processes. Thus an integrated system approach of complex multidisciplinary, non-linear, non-equilibrium processes and phenomena occurring on different length and time scales of the supply chain is required. That is, a good understanding of how phenomena at a smaller length-scale relates to properties and behaviour at a longer length-scale is necessary (from the molecular-scale to the production-scales). This has been defined as the triplet “molecular Processes-Product-Process (3PE)” integrated multiscale approach of chemical engineering. Indeed a modern chemical engineering can be summarized by four main objectives: (1) Increase productivity and selectivity through intensification of intelligent operations and a multiscale approach to processes control: nano and micro-tailoring of materials with controlled structure. (2) Design novel equipment based on scientific principles and new production methods: process intensification using multifunctional reactors and micro-engineering for micro structured equipment. (3) Manufacturing end-use properties to synthesize structured products, combining several functions required by the customer with a special emphasis on complex fluids and solid technology, necessating molecular modeling, polymorph prediction and sensor development. (4) Implement multiscale application of computational chemical engineering modeling and simulation to real-life situations from the molecular-scale to the production-scale, e.g., in order to understand how phenomena at a smaller length-scale relate to properties and behaviour at a longer length-scale. The presentation will emphasize the 3PE multiscale approach of chemical engineering for investigations in the previous objectives and on its success due to the today's considerable progress in the use of scientific instrumentation, in modeling, simulation and computer-aided tools, and in the systematic design methods.     

Natural protein engineering: a uniquely salt-tolerant, but not halophilic, alpha-type carbonic anhydrase from algae proliferating in low- to hyper-saline environments

Dunaliella salina is a unicellular green alga thriving in environments ranging from fresh water to hyper-saline lakes, such as the Dead Sea. An unusual, internally duplicated, 60 kDa alpha-type carbonic anhydrase (dCA I), located on the surface of this alga, is expected to function over a broad range of salinities. It would therefore differ from other carbonic anhydrases that already lose activity at low salinities and also from halophilic proteins that require high salinities for conformational stability. Enzymatic analyses indeed indicated that dCA I retained activity at salt concentrations ranging from low salt to at least 1.5 M NaCl or KCl for CO(2) hydration, 2.0 M NaCl for esterase activity and 0.5 M for bicarbonate dehydration. Although measurements at higher salinities were constrained by the interference of salt in the respective assayed reactions, activity was noticeable even at 4.0 M NaCl. Comparisons of the internally duplicated dCA I to single-domain derivatives indicated that inter-domain interactions played a decisive role in the stability, activity, salt tolerance and pH responses of dCA I. Hence dCA I is a uniquely salt- tolerant protein, retaining an active conformation over a large range of salinities and, as a Zn metalloenzyme, largely immune to the specific inhibitory effects of anions. Its unique features make dCA I a useful model to understand the physico-chemical basis of halotolerance and protein-salt interactions in general.     

From AgI/TiO2 to Ag/TiO2: effects of the annealing temperature on the compositions,porous nanostructures,and visible-light photocatalytic properties

AgI/TiO₂ and Ag/TiO₂ porous nanostructures were synthesized using AgNO₃, KI, thioglycollic acid, and tetrabutyl orthotitanate as a precursor. AgI nanoparticles were used as seeds to initiate the nucleation of a precursor TiO₂ shell, and thioglycollic acid acted as a hydrolysis inhibitor and porosity promoter. The hybridized samples were annealed at different temperatures. Porous AgI/TiO₂ nanostructures were formed at low annealing temperatures (300 and 400 °C). At 600 °C, the porous Ag/TiO₂ nanostructures exhibited a plasmon resonance effect. The formation mechanism of the different porous nanostructures was also investigated. Methylene blue solutions were used as wastewater to evaluate the visible-light photocatalytic activity of the samples. The porous nanostructured photocatalyst exhibited substantially high visible-light-induced photocatalytic activity for the photodegradation of methylene blue compared with pristine AgI and TiO₂ nanoparticles.     

Cu-B2O3/SiO2, an effective catalyst for synthesis of fatty alcohol from hydrogenolysis of fatty acid esters

This work demonstrates that Cu- B₂O₃/SiO₂ is an effective catalyst for synthesis of fatty alcohols from hydrogenolysis of fatty acid esters. Boron oxide not only acts as a textural promoter to increase the dispersion of copper, but also as a structural promoter to decrease the activation energy of hydrogenolysis by 10 kJ/mol. The optimum loading of boron oxide doped is around 6.4 wt%. This chromium-free copper catalyst is seven times as active as the commercial copper chromite (Engelhard Cu-1234E) in the hydrogenolysis of methyl esters at 240°C, 110 bar. Cu- B₂O₃(6.4%)/SiO₂ is a promising catalyst for lower pressure (<150 bar) hydrogenolysis processes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development of an electrodeionization process for removal of nitrate from drinking water Part 2: Multi-species testing

A series of bench-scale experiments was performed with a novel electrodeionization (EDI) process to determine its capacity to remove NO₃⁻ from water in the presence of competing species. Experiments were performed with deionized water that was dosed with selected anionic and cationic species and with two natural waters that contained differing concentrations of dissolved solids. Extended duration experiments were performed to assess the ability of the process to sustain NO₃⁻ removal over a longer period of time. It was found that the use of ion-selective resins in the EDI unit resulted in a process that was more nitrate selective and energy efficient that when a general anion-exchange resin was employed. Operation in EDI mode was found to be superior to operation without resins (ED mode). The most highly selective and energy-efficient operation was at the lowest applied voltage of 2 V per membrane pair. The impact of competing species on NO₃⁻ flux was independent of the competing species when expressed on an equivalence basis. At elevated concentrations of multiple competing species the flux of NO₃⁻ was reduced. The removal of NO₃⁻ from two natural water streams revealed the significance of the water composition on the performance of the EDI unit with respect to the selectivity of NO₃⁻ removal and energy consumption. When treating the Manotick well water, the EDI unit required more energy per equivalence of NO₃⁻ removed and was less selective than when treating the Ottawa potable water that was lower in dissolved solids. Extended duration experiments with the dosed Ottawa water over a period of 48 h did not reveal any decline in fluxes.     

Enniatins fromFusarium avenaceum isolated from balsam fir foliage and their toxicity to spruce budworm larvae,Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae)

Material extracted from hyphae ofFusarium avenaceum, isolated from foliage of balsam fir,Abies balsamea, was toxic to spruce budworm larvae when incorporated into insect diet. The major insecticidal component of the toxic fraction was identified by chemical and spectroscopic methods as enniatin complex, rich in enniatin A/A₁. Possible ecological implications of these observations are considered.     

Synthesis,Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amide)s

Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.     

Mechanistic Details to Facilitate Applications of an Exceptional Catalyst, Methyltrioxorhenium: Encouraging Results from Oxygen-18 Isotopic Probes

Using oxygen-18 labeled probes, the deactivation of the catalyst methyltrioxorhenium in oxidation reactions using hydrogen peroxide has been shown to result from the nucleophilic attack of HOO^? on the parent catalyst rather than by HO^? attack on intermediate A, opening possible routes to enhanced catalyst durability.     

Hybrid FSC membrane for CO2 removal from natural gas: Experimental,process simulation,and economic feasibility analysis

The novel fixed‐site‐carrier (FSC) membranes were prepared by coating carbon nanotubes reinforced polyvinylamine/polyvinyl alcohol selective layer on top of ultrafiltration polysulfone support. Small pilot‐scale modules with membrane area of 110–330 cm² were tested with high pressure permeation rig. The prepared hybrid FSC membranes show high CO₂ permeance of 0.084–0.218 m³ (STP)/(m² h bar) with CO₂/CH₄ selectivity of 17.9–34.7 at different feed pressures up to 40 bar for a 10% CO₂ feed gas. Operating parameters of feed pressure, flow rate, and CO₂ concentration were found to significantly influence membrane performance. HYSYS simulation integrated with ChemBrane and cost estimation was conducted to evaluate techno‐economic feasibility of a membrane process for natural gas (NG) sweetening. Simulation results indicated that the developed FSC membranes could be a promising candidate for CO₂ removal from low CO₂ concentration (10%) NGs with a low NG sweetening cost of 5.73E?3 $/Nm³ sweet NG produced. © 2014 American Institute of Chemical Engineers AIChE J 60: 4174–4184, 2014     

NH2SO3H-SiO2:一种经济高效可重复利用的糖类全乙酰催化剂

在糖化学中全乙酰保护的糖类化合物是非常便宜而且用途广泛的起始原料.对于糖类的全乙酰化反应,NH2SO3H-SiO2是一种高效的催化剂,以各种糖为底物收率均超过90%.回收的NH2SO3H-SiO2可以重复使用而活性没有明显下降.     

2-Mercaptoimidazole Covalently Bonded to a Silica Gel Surface for the Selective Separation of Mercury(II) from an Aqueous Solution

Abstract

Silica gel with a specific surface area of 365 m²·g^?1 and an average pore diameter of 60 Å was chemically modified with 2-mercaptoimidazole. The degree of functionalization of the covalently attached molecule, (≡SiO)₃(CH₂)₃—MI, where MI is the 2-mercaptoimidazole bound to the silica surface by a propyl group, was 0.58 mmol·g^?1. In individual metal adsorption experiments from aqueous solutions by the batch procedure, the affinity order was Hg^II « Cd^II > Cu^II ～ Zn^II ～ Pb^II > Mn^II at solution pHs between 4 and 7. Due to the high affinity by the sulfur atom, Hg^II is strongly bound to the functional groups. When solution containing a mixture of Hg^II, Cd^II, Cu^II, Zn^II, Pb^II, and Mn^II ions was passed through a column packed with the adsorbent, Hg^II was the only one whose adsorption and elution was not affected by the presence of other ions.