126 research outputs found

    Glucuronic acid as a helix-inducing linker in short peptides

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    A new strategy is demonstrated for making peptides helical, using a carbohydrate to bridge between sidechains at each end of a pentapeptide. CD and NMR spectra establish that both an α-helix and a 310-helix structure can form depending upon the bridge

    Facile synthesis of mono- and bis-methylated Fmoc-Dap, -Dab and -Orn amino acids

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    A new methodology for the synthesis of side chain mono- or bis-methylated Fmoc-Dap, -Dab and -Orn amino acids was developed by probing the reactivity of commercially available Fmoc amino acids

    Alpha helix nucleation by a simple cyclic tetrapeptide

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    The simple cyclic tetrapeptide cyclo-(1,4)-[Ala-Arg-Ala-homoGlu]-NH2 (3) is shown to adopt an unusual alpha-turn structure, which is not alpha-helical but can nucleate alpha-helicity when attached to the N-terminus of either model peptides or two biologically relevant peptides. This new N-terminal helix-capping macrocycle provides very simple and rapid synthetic access to alpha-helical peptide structures

    A Conceptual Design and Numerical Analysis for a Small-Scale and Low-Cost Plastic Recycling Machine

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    A new conceptual design for a small-scale and low-cost plastic recycling machine is generated by combining melting part and compression process. Starting with one of the outstanding requirements is in terms of an affordable-priced machine that can perform two processes with high accuracy and capacity, some issues related to balancing among quality, capacity and cost of machine occurred during a discussion. After implementing various designing methods such as Quality Function Deployment, Reverse Engineering, Morphological Matrix and Pugh Method, an idea of final concept about using an electric oven and hydraulic system to melt down and compress plastic tile which has a dimension of 300x300x9 mm was created. The design of concept is divided into two parts which are mechanical and electrical systems. In a mechanical section, the technical drawing and simulation are made to see how machine performs under operation. Besides, we examined the forces that applied in the moulds to evaluate the strength of the system. In heating and electricity section, we chose electrical components, designed oven parameters and conducted the heating simulation on the mould. In addition, the heating and cooling time was calculated based on the principles of thermodynamics and heat transfer. Furthermore, the manufacturing plan is created to estimate the essential resources producing a certain number of heat-forming machines. In general, the machine needs to be prototyped for controlling its main function and finding practical issues. After that, some improvements could be made to enhance efficiency and increase capacity by designing an optimal mould to more heat absorb and reduce post process, calculate and design more efficient oven, create faster lock mechanism and other improvements for an automatizing machine

    Comparative α-Helicity of Cyclic Pentapeptides in Water

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    Helix-constrained polypeptides have attracted great interest for modulating protein-protein interactions (PPI). It is not known which are the most effective helix-inducing strategies for designing PPI agonists/antagonists. Cyclization linkers (X-1-X-5) were compared here, using circular dichroism and 2D NMR spectroscopy, for a-helix induction in simple model pentapeptides, Ac-cyclo(1,5)-[X-1-Ala-Ala-Ala-X-5]-NH2, in water. In this very stringent test of helix induction, a Lys1 -> Asp5 lactam linker conferred greatest alpha-helicity, hydrocarbon and triazole linkers induced a mix of alpha- and 3(10)-helicity, while thio-and dithioether linkers produced less helicity. The lactam-linked cyclic pentapeptide was also the most effective a-helix nucleator attached to a 13-residue model peptide

    A facile synthesis and properties of bismuth vanadate (BiVO4) photocatalyst by hydrothermal method

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    In this study, BiVO4 photocatalysts were synthesized by hydrothermal method using Bi(NO3)3 5H2O and NH4VO3 as raw materials followed by calcination at different temperatures in the range from 350 °C to 600 °C. The as-synthesized BiVO4 samples were characterized by a number of physicochemical techniques including X-ray diffraction (XRD), Raman analysis, Scanning Electron Microscopy (SEM), and UV-Visible (UV-Vis) light diffuse reflectance spectrophotometry. The effect of temperatures calcination on structure, surface morphology, visible-light photocatalytic activity and light absorption performance of BiVO4 was discussed in details

    The impact of albendazole treatment on the incidence of viral- and bacterial-induced diarrhea in school children in southern Vietnam: study protocol for a randomized controlled trial

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    Anthelmintics are one of the more commonly available classes of drugs to treat infections by parasitic helminths (especially nematodes) in the human intestinal tract. As a result of their cost-effectiveness, mass school-based deworming programs are becoming routine practice in developing countries. However, experimental and clinical evidence suggests that anthelmintic treatments may increase susceptibility to other gastrointestinal infections caused by bacteria, viruses, or protozoa. Hypothesizing that anthelmintics may increase diarrheal infections in treated children, we aim to evaluate the impact of anthelmintics on the incidence of diarrheal disease caused by viral and bacterial pathogens in school children in southern Vietnam.This is a randomized, double-blinded, placebo-controlled trial to investigate the effects of albendazole treatment versus placebo on the incidence of viral- and bacterial-induced diarrhea in 350 helminth-infected and 350 helminth-uninfected Vietnamese school children aged 6-15 years. Four hundred milligrams of albendazole, or placebo treatment will be administered once every 3 months for 12 months. At the end of 12 months, all participants will receive albendazole treatment. The primary endpoint of this study is the incidence of diarrheal disease assessed by 12 months of weekly active and passive case surveillance. Secondary endpoints include the prevalence and intensities of helminth, viral, and bacterial infections, alterations in host immunity and the gut microbiota with helminth and pathogen clearance, changes in mean z scores of body weight indices over time, and the number and severity of adverse events.In order to reduce helminth burdens, anthelmintics are being routinely administered to children in developing countries. However, the effects of anthelmintic treatment on susceptibility to other diseases, including diarrheal pathogens, remain unknown. It is important to monitor for unintended consequences of drug treatments in co-infected populations. In this trial, we will examine how anthelmintic treatment impacts host susceptibility to diarrheal infections, with the aim of informing deworming programs of any indirect effects of mass anthelmintic administrations on co-infecting enteric pathogens.ClinicalTrials.gov: NCT02597556 . Registered on 3 November 2015

    Helical cyclic pentapeptides constrain HIV-1 Rev peptide for enhanced RNA binding

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    HIV-1 Rev is a 116 residue transporter protein that enters the host cell nucleus and uses its 17 amino acid segment (Rev34–50) to bind and capture a specific piece of RNA, the Rev Response Element (RRE), for transport to the cytoplasm. This is critical for HIV replication. In isolation, Rev34–50 shows negligible structure in water, but is alpha helical in a mixture of water and 2,2,2-trifluoroethanol (TFE) or when bound to RRE. Here we report that helix-constrained cyclic pentapeptides, either appended to the N-terminus or incorporated within Rev34–50, are efficient helix nucleators in water. They induce up to 90% alpha helicity for isolated Rev peptides in water and confer high RNA-binding affinity
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