Escherichia coli single-stranded DNA-binding protein,a molecular tool for improved sequence quality in pyrosequencing

Pyrosequencing is a four-enzyme bioluminometric DNA sequencing technique based on a DNA sequencing by synthesis principle. Currently, the technique is limited to analysis of short DNA sequences exemplified by single-nucleotide polymorphism analysis. In order to expand the field for pyrosequencing, the read length needs to be improved and efforts have been made to purify reaction components as well as add single-stranded DNA-binding protein (SSB) to the pyrosequencing reaction. In this study, we have performed a systematic effort to analyze the effects of SSB by comparing the pyrosequencing result of 103 independent complementary DNA (cDNA) clones. More detailed information about the cause of low quality sequences on templates with different characteristics was achieved by thorough analysis of the pyrograms. Also, real-time biosensor analysis was performed on individual cDNA clones for investigation of primer annealing and SSB binding on these templates. Results from these studies indicate that templates with high performance in pyrosequencing without SSB possess efficient primer annealing and low SSB affinity. Alternative strategies to improve the performance in pyrosequencing by increasing the primer-annealing efficiency have also been evaluated.     

Magnetic‐based picolinaldehyde–melamine copper complex for the one‐pot synthesis of hexahydroquinolines via Hantzsch four‐component reactions

A picolinaldehyde–melamine copper complex was loaded on a magnetic Fe₃O₄ core, so that it contained 0.33 mmol of Cu per gram, and was used as an efficient catalyst. The as‐synthesized catalyst was characterized using various techniques, including Fourier transform infrared spectroscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and thermogravimetric analysis. The catalyst was used to activate the raw materials in the synthesis of hexahydroquinoline derivatives in one‐pot four‐component reactions. Low reaction time (minutes versus half an hour), solvent‐free condition and magnetically separable catalyst are some salient features of the developed catalyst. Also, the optimum amount of catalyst and temperature were determined as 0.07 g and 87.6 °C, respectively, which were obtained using response surface methodology and optimization techniques.     

Quantum Watermarking Using Entanglement Swapping

Digital watermarking is the process of embedding information into a digital signal in a way that is difficult to remove. In this article a secure quantum watermarking using entanglement swapping is proposed. Here the entanglement swapping is employed to build up a hidden layer of secure message under the conventional first layer of secure information sequence. In this protocol by insuring the security of transmission of the first layer of information sequence the security of the hidden secret messages is also proved to be reliable regardless of whether the hidden channel has been detected or not.     

Trimesic acid is a suitable building block in triple four-component Ugi reaction: access to unique trivalent compounds

Monatshefte für Chemie - Chemical Monthly - A triple four-component Ugi reaction of isocyanide, amine, aldehyde, and trimesic acid as the acid component with three acidic functional groups in...     

Nonlinear dynamics of a flexible rotor on tilting pad journal bearings experiencing rub–impact

Nonlinear Dynamics - Rub–impact phenomenon occurring in hydrodynamic journal bearings is one of the main malfunctions in rotating machines and causes undesirable dynamic behavior. In order to...     

Per Aqueous Liquid Chromatography (PALC) as a Simple Method for Native Separation of Protein A

Staphylococcal protein A (protein A) is an important protein frequently used in research studies within the fields of biomedicine and biotechnology. Due to some limitations in available protein purification methods which can hold the native structure of the protein A without changing the folding or adding histidine to structure of this protein, its separation in the native form is difficult. In this study, a new cost-effective and powerful technique was introduced for separation of the full-length and truncated forms of recombinant protein A, without any alteration in their 3D structures. Per aqueous liquid chromatography with bare silica gel stationary phase and water:acetonitrile as the mobile phase was proved to be an attractive choice among the range of separation methods. Similar to hydrophilic liquid chromatography, this method employs high percentage of water in mobile phase. The effects of mobile phase composition, pH, and salt concentration on the retention behavior of protein A on bare silica gel stationary phases were investigated. In this method, applying high amounts of aqueous solvent accompanied by a minimum percentage of organic solvent could successfully separate protein A with preservation of folding, and any affinity-tagged group such as histidine has not occurred on its structure. Purity of the fractions obtained by the proposed method was confirmed using SDS-PAGE, western blotting, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. According to the results of ELISA, separated proteins retained their ability of binding to antibody.     

An efficient chemoselective synthesis of O-vinylaryl systems using acetylenic esters and dihydroxybenzenes in the presence of triphenylphosphine or alkyl isocyanides

<正>The addition of 2,4-dihydroxyaceto(and benzo)phenone to propiolic ester is catalyzed by triphenylphosphine or tert-butyl isocyanide to form O-vinyl aryl derivatives in fairly good yields.