Polymorphic Protective Dps-DNA Co-Crystals by Cryo Electron Tomography and Small Angle X-Ray Scattering.

Rapid increase of intracellular synthesis of specific histone-like Dps protein that binds DNA to protect the genome against deleterious factors leads to in cellulo crystallization-one of the most curious processes in the area of life science at the moment. However, the actual structure of the Dps-DNA co-crystals remained uncertain in the details for more than two decades. Cryo-electron tomography and small-angle X-ray scattering revealed polymorphous modifications of the co-crystals depending on the buffer parameters.

The nature of the ligand's side chain interacting with the S1'-subsite of metallocarboxypeptidase T (from Thermoactinomyces vulgaris) determines the geometry of the tetrahedral transition complex.

The carboxypeptidase T (CPT) from Thermoactinomyces vulgaris has an active site structure and 3D organization similar to pancreatic carboxypeptidases A and B (CPA and CPB), but differs in broader substrate specificity. The crystal structures of CPT complexes with the transition state analogs N-sulfamoyl-L-leucine and N-sulfamoyl-L-glutamate (SLeu and SGlu) were determined and compared with previously determined structures of CPT complexes with N-sulfamoyl-L-arginine and N-sulfamoyl-L-phenylalanine (SArg and SPhe). The conformations of residues Tyr255 and Glu270, the distances between these residues and the corresponding ligand groups, and the Zn-S gap between the zinc ion and the sulfur atom in the ligand's sulfamoyl group that simulates a distance between the zinc ion and the tetrahedral sp3-hybridized carbon atom of the converted peptide bond, vary depending on the nature of the side chain in the substrate's C-terminus.

The binding of precipitant ions in the tetragonal crystals of hen egg white lysozyme.

The bonds between lysozyme molecules and precipitant ions in single crystals grown with chlorides of several metals are analysed on the basis of crystal structure data. Crystals of tetragonal hen egg lysozyme (HEWL) were grown with chlorides of several alkali and transition metals (LiCl, NaCl, KCl, NiCl and CuCl) as precipitants and the three-dimensional structures were determined at 1.35 Å resolution by X-ray diffraction method.

The dimeric ectodomain of the alkali-sensing insulin receptor-related receptor (ectoIRR) has a droplike shape.

Insulin receptor-related receptor (IRR) is a receptor tyrosine kinase of the insulin receptor family and functions as an extracellular alkali sensor that controls metabolic alkalosis in the regulation of the acid-base balance. In the present work, we sought to analyze structural features of IRR by comparing them with those of the insulin receptor, which is its closest homolog but does not respond to pH changes. Using small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM), we investigated the overall conformation of the recombinant soluble IRR ectodomain (ectoIRR) at neutral and alkaline pH.

Preparation and thermal treatment influence on Pt-decorated electrospun carbon nanofiber electrocatalysts.

Crystalline platinum nanoparticles supported on carbon nanofibers were synthesized for use as an electrocatalyst for polymer electrolyte membrane fuel cells. The nanofibers were prepared by a method of electrospinning from polymer solution with subsequent pyrolysis. Pt nanoneedles supported on polyacrylonitrile pyrolyzed electrospun nanofibers were synthesized by chemical reduction of H[PtCl] in aqueous solution.

Transformation of the dermal collagen framework under laser heating.

The aim of this study was to compare between the changes undergone by the dermal collagen framework when heated by IR laser radiation and by traditional means and to reveal the specific features of the dermal matrix modification under moderate IR laser irradiation. Rabbit skin specimens were heated to 50°C, 55°C, 60°C and 65°C in a calorimeter furnace and with a 1.68-μm fiber Raman laser.

Dodecamers derived from the crystal structure were found in the pre-crystallization solution of the transaminase from the thermophilic bacterium by small-angle X-ray scattering.

The pre-crystallization solution of the transaminase from (TaTT) has been studied by small-angle X-ray scattering (SAXS). Regular changes in the oligomeric composition of the protein were observed after the addition of the precipitant. Comparison of the observed oligomers with the crystal structure of TaTT (PDB ID 6GKR) shows that dodecamers may act as building blocks in the growth of transaminase single crystals.

Characteristic features of polytypism in compounds with the LaWO-type structure.

Crystals with the LaWO-type structure (6H and 5H polytypes) were obtained by a self-flux method from high-temperature solutions. Some of the crystal samples were studied by single-crystal X-ray structure analysis. The diffraction patterns indicated that two phases co-exist in each sample.

Physical properties and cytotoxicity of silver nanoparticles under different polymeric stabilizers.

At present day, silver nanoparticles are widely used in different fields of human activity. Due to the unique combination of physical and chemical properties, silver nanoparticles have high reactivity and antibacterial activity against microorganisms. For the same reason, silver nanoparticles can render a cytotoxic effect on eukaryotic cells.

Theoretical insights into UV-Vis absorption spectra of difluoroboron β-diketonates with an extended π system: An analysis based on DFT and TD-DFT calculations.

The UV-Vis absorption spectra of difluoroboron β-diketonates with aromatic substituents at the β-carbon are studied thoroughly using DFT and TD-DFT with the CAM-B3LYP functional. The complicated experimental spectra of these dyes can be correctly interpreted by considering their structural features. A closer look at the calculated data shows that the conformational flexibility of these compounds markedly influences their spectral shape.

Octa-repeat domain of the mammalian prion protein mRNA forms stable A-helical hairpin structure rather than G-quadruplexes.

Misfolding and aggregation of prion protein (PrP) causes neurodegenerative diseases like Creutzfeldt-Jakob disease (CJD) and scrapie. Besides the consensus that spontaneous conversion of normal cellular PrP into misfolded and aggregating PrP is the central event in prion disease, an alternative hypothesis suggests the generation of pathological PrP by rare translational frameshifting events in the octa-repeat domain of the PrP mRNA. Ribosomal frameshifting most commonly relies on a slippery site and an adjacent stable RNA structure to stall translating ribosome.

Mesoporous particle-based microcontainers for intranasal delivery of imidazopyridine drugs.

The aim of this study was to develop mesoporous containers for entrapment of imidazopyridines, such as sedative-hypnotic medicine zolpidem, anxiolytic agent alpidem and their derivatives. For this purpose, calcium carbonate (size 1.2 µm (PDI: 0.

Probing of complex carbon nanofiber paper as gas-diffusion electrode for high temperature polymer electrolyte membrane fuel cell.

The development of fuel cells is an important part of alternative energy studies. High-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) is a very promising and commercialized type of fuel cell since it allows the use of hydrogen contaminated with CO. However, current advances in HT-PEMFC are based on searching for more sustainable materials for the membrane electrode assembly.

Pre-crystallization phase formation of thermolysin hexamers in solution close to crystallization conditions.

Communicated by Ramaswamy H. Sarma.

Composite materials based on Ag nanoparticles in situ synthesized on the vaterite porous matrices.

We have designed sensors based on Ag nanoparticles synthesized in situ on the vaterite beads. In this article we demonstrate an approach to produce size controllable spherical and elliptical vaterite particles and discuss time-dependent in situ Ag nanoparticles synthesis and its potential effect on surface-enhanced Raman scattering. The time dependent silver reduction synthesis in inorganic porous particles allows to regulate the number and size of Ag nanoparticles.

Crystal structure of mutant carboxypeptidase T from Thermoactinomyces vulgaris with an implanted S1' subsite from pancreatic carboxypeptidase B.

A site-directed mutagenesis method has been used to obtain the G215S/A251G/T257A/D260G/T262D mutant of carboxypeptidase T from Thermoactinomyces vulgaris (CPT), in which the amino-acid residues of the S1' subsite are substituted by the corresponding residues from pancreatic carboxypeptidase B (CPB). It was shown that the mutant enzyme retained the broad, mainly hydrophobic selectivity of wild-type CPT. The mutant containing the implanted CPB S1' subsite was crystallized and its three-dimensional structure was determined at 1.

Laboratory time-resolved X-ray diffractometry for investigation of reversible structural changes induced in single crystals by external electric field.

Time-resolved technique of X-ray diffraction curve measurement was implemented at a laboratory X-ray source using a high-speed data acquisition system. The time resolution of up to 100 s was achieved via this X-ray diffractometry technique in the experiment of rocking curve dynamics measurement in a piezoelectric lanthanum-gallium silicate crystal under the influence of high voltage periodic pulsed electric field with an amplitude of 3.08 kV/mm corresponding to the pre-breakdown state.

Formation of hybrid higher-order cylindrical vector beams using binary multi-sector phase plates.

Nowadays, the well-known cylindrical vector beams (CVBs) - the axially symmetric beam solution to the full-vector electromagnetic wave equation - are widely used for advanced laser material processing, optical manipulation and communication and have a great interest for data storage. Higher-order CVBs with polarisation order greater than one and superpositions of CVBs of various orders (hybrid CVBs) are especially of interest because of their great potential in contemporary optics. We performed a theoretical analysis of the transformation of first-order CVBs (radially and azimuthally polarised beams) into hybrid higher-order ones using phase elements with complex transmission functions in the form of the cosine or sine functions of the azimuthal angle.

Human MICAL1: Activation by the small GTPase Rab8 and small-angle X-ray scattering studies on the oligomerization state of MICAL1 and its complex with Rab8.

Human MICAL1 is a member of a recently discovered family of multidomain proteins that couple a FAD-containing monooxygenase-like domain to typical protein interaction domains. Growing evidence implicates the NADPH oxidase reaction catalyzed by the flavoprotein domain in generation of hydrogen peroxide as a second messenger in an increasing number of cell types and as a specific modulator of actin filaments stability. Several proteins of the Rab families of small GTPases are emerging as regulators of MICAL activity by binding to its C-terminal helical domain presumably shifting the equilibrium from the free - auto-inhibited - conformation to the active one.

Direct shape determination of intermediates in evolving macromolecular solutions from small-angle scattering data.

Many important biological processes like amyloid formation, viral assembly can be monitored . Small-angle X-ray scattering (SAXS) is one of the most effective techniques to structurally characterize these processes in solution. For monodisperse systems and some oligomeric mixtures, low-resolution shapes can be determined from the SAXS data, but for evolving systems, such analysis is hampered by the presence of multiple species and no direct reconstruction procedures are available.

Crystal structure of Escherichia coli purine nucleoside phosphorylase complexed with acyclovir.

Escherichia coli purine nucleoside phosphorylase (PNP), which catalyzes the reversible phosphorolysis of purine ribonucleosides, belongs to the family I hexameric PNPs. Owing to their key role in the purine salvage pathway, PNPs are attractive targets for drug design against some pathogens. Acyclovir (ACV) is an acyclic derivative of the PNP substrate guanosine and is used as an antiviral drug for the treatment of some human viral infections.

A novel formulation of zolpidem for direct nose-to-brain delivery: synthesis, encapsulation and intranasal administration to mice.

Objectives: Anxiolytic drug zolpidem was incorporated into the microcontainers based on mesoporous calcium carbonate particles modified by diethylaminoethyl-dextran/hyaluronic acid shell. The release of zolpidem in saline solution and in polymer film modelling nasal mucosa was investigated. The anxiolytic effect of zolpidem upon intranasal administration of microcontainers and free medicine was determined by in vivo experiments on mice.

Heat-driven size reduction of biodegradable polyelectrolyte multilayer hollow capsules assembled on CaCO template.

Aiming to explore elevated temperatures as a tool for miniaturization of biodegradable polymer multilayer capsules, assembled on spherical vaterite micron- and submicron-sized particles, we subject the shells composed of dextran sulfate (DS) and poly-L-arginine (Parg) to a heat treatment. Changes of the capsule size are studied at various temperatures and ionic strengths of the continuous phase. Unlike some synthetic polymer multilayer shells (their response to heat treatment depends on the number of layers and their arrangement), the biodegradable Parg/DS capsules exhibit size reduction and profound compaction regardless of their initial size, number of polymer layers and polymer layer sequence.

Correction: Ab initio calculation of energy levels of trivalent lanthanide ions.

Correction for 'Ab initio calculation of energy levels of trivalent lanthanide ions' by Alexandra Ya. Freidzon et al., Phys.