Sensitivity‐Enhanced 13C‐NMR Spectroscopy for Monitoring Multisite Phosphorylation at Physiological Temperature and pH

Abundant phosphorylation events control the activity of nuclear proteins involved in gene regulation and DNA repair. These occur mostly on disordered regions of proteins, which often contain multiple phosphosites. Comprehensive and quantitative monitoring of phosphorylation reactions is theoretically achievable at a residue‐specific level using ¹H‐¹⁵N NMR spectroscopy, but is often limited by low signal‐to‐noise at pH>7 and T>293 K. We have developed an improved ¹³Cα‐¹³CO correlation NMR experiment that works equally at any pH or temperature, that is, also under conditions at which kinases are active. This allows us to obtain atomic‐resolution information in physiological conditions down to 25 μm . We demonstrate the potential of this approach by monitoring phosphorylation reactions, in the presence of purified kinases or in cell extracts, on a range of previously problematic targets, namely Mdm2, BRCA2, and Oct4.     

Effect of interface in bilayer polydiphenylenephthalide film on electron transport

The results of studies of multilayer film structures based on a wide-gap polymer using the time of flight technique are shown. Experimental data showed that transport of charge carriers depends strongly on the presence of a polymer/polymer interface. The possibility is shown of increasing the threshold thickness of the experimental structure, in which effects of switching to a highly conducting state induced by uniaxial mechanical pressure are also found. Preliminary interpretation of the obtained data is performed.     

Effect of excessive pressure on the drift mobility of charge carriers in poly(diphenylene phthalide) films

The electron-hole transport in poly(diphenylene phthalide) films has been investigated. The dependence of the drift mobility of charge carriers on the excessive mechanical pressure has been studied using the time-of-flight method. It has been revealed that, with an increase in the thickness of the polymer film, the dispersive transport of charge carries gives way to the quasi-dispersive transport. In thin films in the prethreshold range (i.e., before switching of the samples to the highly conductive state under excessive pressure), the electron mobility increases and exceeds the hole mobility. The experimental results have been discussed in the framework of the model describing the transport through the channels formed by metastable electron-hole pairs.     

The dynamic nature of amyloid beta (1-40) aggregation

In this paper, we characterize the dynamic nature of the full amyloid beta (1-40) (Aβ (1-40)) aggregates. We labeled the peptide with either 5-carboxytetramethylrhodamine (TAMRA) or with fluorescein-isothiocyanate (FITC). The labeled peptides were mixed after separate fibrillization, and the dynamic changes in the structure of the fibrils were imaged using confocal microscopy. Fluorescence resonance energy transfer (FRET) measurements showed that the Aβ (1-40) peptides detach from and reattach to the fibrils in a biologically relevant timescale (days). With time, the two peptides mix at the molecular level. This process is concentration dependent and occurs primarily in the external parts of the aggregates with a half time between 4 and 7 days. This study shows that the combination of confocal microscopy and FRET analysis is a facile method for studying dynamic processes in supra-molecular aggregates.     

Ionic polymerization in an electric field and consequences of the spatial redistribution of growing macroions and counterions

Reaction mixtures in which polymerization processes proceed are investigated both in an electric field and under classical conditions. The observed kinetic effects are explained using a model concept of the primary contribution to the revealed field effects from the dissociation of ion pairs due to the spatial redistribution of ions. This model may be applied to both cationic and anionic polymerization processes.     

Molecular dynamics study of perovskite structures with modified interatomic interaction potentials

The structure of compounds with the perovskite structure ABX₃ (A and B are cations, X are anions O^2—, F^—, Cl^—, Br^—, and I^—), which are widely used in engineering due to unique electrical, optical, and photovoltaic properties, has been considered. Hybrid organic—inorganic halide perovskites important for photovoltaics of a new generation are worth mentioning; they contain cations of organic nitrogen bases as monovalent cations. A molecular dynamics (MD) study of the CaTiO₃ base structure (Ca²⁺, Ti⁴⁺, and O^2—) has been performed in order to develop the methodology of computer simulation and optimization of the shape and parameters of atomic potentials for perovskite systems.     

Electrodeposited polyaniline/Cu2ZnSnSe4 heterojunction

Journal of Solid State Electrochemistry - One-step method for the electrodeposition of thin Cu2ZnSnSe4 (CZTSe) film onto a polyaniline/FTO/glass substrate was developed. Polyaniline film was...     

New Unsymmetrically Substituted Benzothiadiazole-Based Luminophores: Synthesis,Optical, Electrochemical Studies,Charge Transport,and Electroluminescent Characteristics

Three new benzothiadiazole (BTD)-containing luminophores with different configurations of aryl linkers have been prepared via Pd-catalyzed cross-coupling Suzuki and Buchwald–Hartwig reactions. Photophysical and electroluminescent properties of the compounds were investigated to estimate their potential for optoelectronic applications. All synthesized structures have sufficiently high quantum yields in film. The BTD with aryl bridged carbazole unit demonstrated the highest electrons and holes mobility in a series. OLED with light-emitting layer (EML) based on this compound exhibited the highest brightness, as well as current and luminous efficiency. The synthesized compounds are not only luminophores with a high photoluminescence quantum yield, but also active transport centers for charge carriers in EML of OLED devices.     

The influence of light on the conduction switching effect in thin polymer films

The effect of exposure to visible light on pressure- and field-induced switching from the low-conductivity to the high-conductivity state in thin polymer films was experimentally studied. The switching effect was observed in poly(diphenylene phthalide) and polyvinylcarbazole layers doped with a cyanine dye. Doping with the dye reduces the voltage at which the polymer is switched to the conducting state. However, an Al—dye complex is formed with time, which results in an increase in the switching voltage and pressure. It was found that illumination leads to the appearance of additional conductivity in the sample; in the samples prone to switching to the conducting state, light stimulates switching and leads to blocking the injection sites for charge carriers in the low-conductivity state.     

Sensitivity-Enhanced 13C-NMR Spectroscopy for Monitoring Multisite Phosphorylation at Physiological Temperature and pH

Abundant phosphorylation events control the activity of nuclear proteins involved in gene regulation and DNA repair. These occur mostly on disordered regions of proteins, which often contain multiple phosphosites. Comprehensive and quantitative monitoring of phosphorylation reactions is theoretically achievable at a residue-specific level using ¹H-¹⁵N NMR spectroscopy, but is often limited by low signal-to-noise at pH>7 and T>293 K. We have developed an improved ¹³Cα-¹³CO correlation NMR experiment that works equally at any pH or temperature, that is, also under conditions at which kinases are active. This allows us to obtain atomic-resolution information in physiological conditions down to 25 μm . We demonstrate the potential of this approach by monitoring phosphorylation reactions, in the presence of purified kinases or in cell extracts, on a range of previously problematic targets, namely Mdm2, BRCA2, and Oct4.