el NVee Meets Xander, the Self-proclaimed "Kkondae" SBN By world.kbs.co.kr Published On :: 2024-11-11 +09:00 Get ready for an unforgettable first encounter! This week on I Feel You, our regular NVee meets special DJ Xander—the ultimate non-kkondae idol sbn! From hilarious icebreakers to shared stories...[more...] Full Article Economy&It
el How to Delete a Page in Word on Mac and Windows By computer.howstuffworks.com Published On :: Fri, 14 Jun 2024 10:05:02 -0400 Can't figure out how to delete an entire page in Word? It's easy. We'll show you how. Full Article
el Leo and Pisces Compatibility: Why Their Relationship Is Complex but Worth It By entertainment.howstuffworks.com Published On :: Sat, 09 Nov 2024 05:00:05 -0500 Explore Leo and Pisces compatibility, uncovering their strengths, weaknesses, and whether these zodiac signs can make their relationship work. Full Article
el Is Seeing 911 a Divine Message? Here’s What Angel Number 911 Means By entertainment.howstuffworks.com Published On :: Mon, 11 Nov 2024 05:15:03 -0500 Discover the spiritual meaning of angel number 911. Learn how 911 symbolizes growth, change, and guidance from the universe in life, love, and personal journeys. Full Article
el Gemini vs. Capricorn: What Makes Their Relationship Unique? By entertainment.howstuffworks.com Published On :: Tue, 12 Nov 2024 05:15:03 -0500 Is Gemini and Capricorn compatibility strong? Discover the unique dynamics, strengths, and challenges that Gemini and Capricorn face in love, friendship, and beyond. Full Article
el Zodiac Signs Elements: Discover the Power Behind Each Element By entertainment.howstuffworks.com Published On :: Wed, 13 Nov 2024 05:30:03 -0500 Discover the unique traits of each zodiac element—fire, earth, air, and water. Uncover how these elements shape personalities and compatibility in astrology. Full Article
el Finance Minister: Trump’s Reelection Likely to Have ‘Considerable’ Impact on S. Korean Economy By world.kbs.co.kr Published On :: Thu, 07 Nov 2024 09:43:01 +0900 [Economy] : Finance Minister Choi Sang-mok said Thursday that he expects Donald Trump’s reelection to have a “considerable” impact on the South Korean economy. The minister made the remarks Wednesday in Seoul during a meeting of ministers concerned with the economy, the morning after Donald Trump won the U.S. ...[more...] Full Article Economy
el Gov’t, Businesses Discuss Response to Donald Trump’s Reelection By world.kbs.co.kr Published On :: Thu, 07 Nov 2024 16:09:19 +0900 [Economy] : Representatives of the government and the business community met to discuss former President Donald Trump’s reelection and how it might affect trade. At a meeting presided over by Minister of Trade, Industry and Energy Ahn Duk-geun on Thursday, participants exchanged views on the likely impact of the ...[more...] Full Article Economy
el Foreign Investors Sell Stocks for Third Consecutive Month By world.kbs.co.kr Published On :: Fri, 08 Nov 2024 15:39:02 +0900 [Economy] : Foreign investors were net sellers in the South Korean stock market for the third month in October. According to data from the Bank of Korea(BOK) on Friday, foreigners sold a net four-point-17 billion U.S. dollars worth of stocks last month. But the latest figure is lower than September’s total of ...[more...] Full Article Economy
el Czech Delegation to Visit S. Korea for Final Contract Negotiations for Nuclear Deal By world.kbs.co.kr Published On :: Mon, 11 Nov 2024 11:27:29 +0900 [Economy] : A large delegation representing Czech power authorities will make a two-week visit to South Korea for working-level negotiations ahead of the conclusion of a final contract for the Czech nuclear power plant project. Korea Hydro and Nuclear Power(KHNP), which was selected in July as the preferred bidder ...[more...] Full Article Economy
el KOSPI Slips below 2,500 Threshold for First Time since Black Monday in August By world.kbs.co.kr Published On :: Tue, 12 Nov 2024 17:55:50 +0900 [Economy] : South Korea’s benchmark Korea Composite Stock Price Index(KOSPI) slipped below the two-thousand-500 threshold on Tuesday for the first time since August’s “Black Monday.” The KOSPI dipped 49-point-09 points, or one-point-94 percent, on Tuesday to close at two-thousand-482-point-57. In the ...[more...] Full Article Economy
el KOSDAQ Falls below 700 for First Time in 2 Months By world.kbs.co.kr Published On :: Wed, 13 Nov 2024 11:20:48 +0900 [Economy] : South Korea’s tech-laden KOSDAQ fell below the 700 mark during trading for the first time in two months. As of 10:12 a.m. Wednesday, the secondary KOSDAQ market stood at 697-point-94, down 12-point-58 points or one-point-77 percent from the previous day. It marks the first time the KOSDAQ has ...[more...] Full Article Economy
el BGS releases 10K maps through updated maps portal - British Geological Survey By news.google.com Published On :: Tue, 16 May 2023 07:00:00 GMT BGS releases 10K maps through updated maps portal British Geological Survey Full Article
el Product development: properties and resources - British Geological Survey By news.google.com Published On :: Wed, 23 Sep 2020 13:28:59 GMT Product development: properties and resources British Geological Survey Full Article
el BGS leads update to maps of the Earth’s magnetic field - British Geological Survey By news.google.com Published On :: Thu, 04 Apr 2024 07:00:00 GMT BGS leads update to maps of the Earth’s magnetic field British Geological Survey Full Article
el Did you feel the earth move? Mini-earthquake recorded on Shropshire/Staffordshire border - Express & Star By news.google.com Published On :: Mon, 14 Oct 2024 07:00:00 GMT Did you feel the earth move? Mini-earthquake recorded on Shropshire/Staffordshire border Express & Star Full Article
el BGS scientist announced as Scottish Government policy fellow - British Geological Survey By news.google.com Published On :: Tue, 06 Feb 2024 15:09:19 GMT BGS scientist announced as Scottish Government policy fellow British Geological Survey Full Article
el First national-scale groundwater model in Great Britain developed - British Geological Survey By news.google.com Published On :: Tue, 14 May 2024 10:50:37 GMT First national-scale groundwater model in Great Britain developed British Geological Survey Full Article
el Delivering a sustainable urban future for Europe through geoscience - British Geological Survey By news.google.com Published On :: Wed, 08 May 2024 16:17:43 GMT Delivering a sustainable urban future for Europe through geoscience British Geological Survey Full Article
el BGS collaborates with Icelandic colleagues to assess windfarm suitability - British Geological Survey By news.google.com Published On :: Thu, 03 Oct 2024 07:00:00 GMT BGS collaborates with Icelandic colleagues to assess windfarm suitability British Geological Survey Full Article
el BGS to help deliver International Centre of Excellence on Sustainable Resource Management - British Geological Survey By news.google.com Published On :: Tue, 27 Feb 2024 16:32:42 GMT BGS to help deliver International Centre of Excellence on Sustainable Resource Management British Geological Survey Full Article
el International geoscience research and development - British Geological Survey By news.google.com Published On :: Sat, 20 Jan 2024 09:25:00 GMT International geoscience research and development British Geological Survey Full Article
el Local MP checks in on development of new geothermal 'living laboratory' in Nottinghamshire - British Geological Survey By news.google.com Published On :: Thu, 19 Sep 2024 07:00:00 GMT Local MP checks in on development of new geothermal 'living laboratory' in Nottinghamshire British Geological Survey Full Article
el Update released for BGS open-source database software, ETL Helper - British Geological Survey By news.google.com Published On :: Tue, 09 Jul 2024 07:00:00 GMT Update released for BGS open-source database software, ETL Helper British Geological Survey Full Article
el Update to BGS’s AGS file utilities tool released - British Geological Survey By news.google.com Published On :: Wed, 19 Jun 2024 07:00:00 GMT Update to BGS’s AGS file utilities tool released British Geological Survey Full Article
el Electromagnetic geophysics in Japan: a conference experience - British Geological Survey By news.google.com Published On :: Wed, 23 Oct 2024 07:00:00 GMT Electromagnetic geophysics in Japan: a conference experience British Geological Survey Full Article
el Local MP helps BGS launch a ‘living laboratory’ - British Geological Survey By news.google.com Published On :: Tue, 05 Mar 2024 08:00:00 GMT Local MP helps BGS launch a ‘living laboratory’ British Geological Survey Full Article
el Crystal structure of nickel orthovanadate (Ni3V2O8) at 299 (3) K and 1323 (8) K: an X-ray diffraction study By journals.iucr.org Published On :: The structure of Ni3V2O8 was studied using X-ray diffraction at temperatures of 299 and 1323 K. No phase transition at high temperature is observed. The variation in V—O bond length is small as compared with the Ni—O bond due to its high rigidity. Full Article text
el Atypical phase transition, twinning and ferroelastic domain structure in bis(ethylenediammonium) tetrabromozincate(II) bromide, [NH3(CH2)2NH3]2[ZnBr4]Br2 By journals.iucr.org Published On :: A unique phase transition, twinning and ferroelastic domain structure in [NH3(CH2)2NH3]2[ZnBr4]Br2 is found. The new additional domain structure is observed at the phase transition on heating, which is preserved after cooling to room temperature. Full Article text
el Variable stoichiometry and salt-cocrystal intermediate in the multicomponents of flucytosine: structural elucidation and its impact on stability By journals.iucr.org Published On :: Five multicomponent solid forms of an antifungal drug flucytosine are reported with a hygroscopic stability study. A detailed CSD search on the cocrystal/salts of flucytosine is evaluated and correlated the structures based on bond angles and bond distances. Full Article text
el Seed layer formation by deposition of micro-crystallites on a revolving substrate: modeling of the effective linear elastic, piezoelectric, and dielectric coefficients By journals.iucr.org Published On :: The rotating substrate method of crystallite deposition is modeled, allowing computation of effective material coefficients of the layers resulting from the averaging. A worked numerical example particularized to 6mm ZnO is provided. Full Article text
el Selective Acceleration and Inhibition of Crystal Growth of Glass Carbamazepine by Low-Concentration Poly(ethylene oxide):Effects of Drug Polymorph By journals.iucr.org Published On :: Low-concentration poly(ethylene oxide) exhibit the polymorph-dependent effects on both the surface and bulk crystal growth of carbamazepine polymorphs. These polymorph-dependent effects of PEO were mainly attributed to the polymer enrichment at the interface and different crystal surface-polymer interactions. Full Article text
el Density functional theory investigation of the phase transition, elastic and thermal characteristics for AuMTe2(M = Ga, In) chalcopyrite compounds By journals.iucr.org Published On :: This study presents the first theoretical predictions of the phase transitions, elastic properties, and thermal behavior of AuMTe2 (M = Ga, In) chalcopyrite compounds. Using density functional theory and the quasi-harmonic Debye model, key mechanical and thermodynamic properties are analyzed, offering insights valuable for future experimental validation. Full Article text
el Crystal structure predictions for molecules with soft degrees of freedom using intermonomer force fields derived from first principles By journals.iucr.org Published On :: Full Article text
el Atypical phase transition, twinning and ferroelastic domain structure in bis(ethylenediammonium) tetrabromozincate(II) bromide, [NH3(CH2)2NH3]2[ZnBr4]Br2 By journals.iucr.org Published On :: 2024-11-04 Single-crystal growth, differential thermal analysis (DTA), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), X-ray structural studies and polarized microscopy observations of bis(ethylenediammonium) tetrabromozincate(II) bromide [NH3(CH2)2NH3]2[ZnBr4]Br2 are presented. A reversible phase transition is described. At room temperature, the complex crystallizes in the monoclinic system. In some cases, the single crystals are twinned into two or more large domains of ferroelastic type with domain walls in the (100) crystallographic plane. DTA and DTG measurements show chemical stability of the crystal up to ∼538 K. In the DSC studies, a reversible isostructural phase transition was revealed at ∼526/522 K on heating/cooling run, respectively. Optical observation on the heating run reveals that at the phase transition the plane of twinning (domain wall) does not disappear and additionally the appearance of a new domain structure of ferroelastic type with domain walls in the planes (101), (101), (100) and (001) is observed. The domain structure pattern is preserved after cooling to the room-temperature phase and the symmetry of this phase is unchanged. Full Article text
el Crystal structure of nickel orthovanadate (Ni3V2O8) at 299 (3) K and 1323 (8) K: an X-ray diffraction study By journals.iucr.org Published On :: 2024-10-23 Nickel orthovanadate is a promising material with potential applications in energy storage and photocatalytic devices. The crystal structure of Ni3V2O8 at 299 (3) K and 1323 (8) K was studied using X-ray powder diffraction. The sample was a single-phase orthorhombic kagome-staircase-Ni3(VO4)2-type structure (space group Cmca) at both temperatures. The phase purity and morphology was studied using energy-dispersive X-ray spectroscopy and scanning electron microscopy. The refined unit-cell parameters at 299 (3) K are a = 5.93384 (4) Å, b = 11.38318 (7) Å and c = 8.23818 (5) Å, and at 1323 (8) K are a = 6.02077 (7) Å, b = 11.48838 (7) Å and c = 8.32611 (9) Å. The obtained results indicate thermal expansion anisotropy, with a largest expansivity along a. Variations in Ni—O and V—O bonds with temperature are observed. The variation in the Ni—O bond is about one order higher in magnitude than that of the V—O bond, signifying the high rigidity of V—O bonds. The unit-cell size variations with rising effective ionic volume of the divalent A ion in the A3B2O8 family [A = Ni, Mg, Zn, Co, Mn (experimental data) and also A = Cu, Cd (theoretical data), B = V or As] are analyzed. Based on experimental and theoretical data, trends within the family are observed and the unit-cell size for reported solid solution of nickel (87%) and copper (13%) mixture in (Ni1–xCux)3V2O8 are predicted. Predictions are also provided for some hypothetical A3B2O8 ternary compound and solid solutions. Full Article text
el X-ray crystallographic structure of a novel enantiopure chiral isothiourea with potential applications in enantioselective synthesis By journals.iucr.org Published On :: 2024-01-01 The synthesis of a chiral isothiourea, namely, (4aR,8aR)-3-phenyl-4a,5,6,7,8,8a-hexahydrobenzo[4,5]imidazo[2,1-b]thiazol-9-ium bromide, C15H17N2S+·Br−, with potential organocatalytic and anti-inflammatory activity is reported. The preparation of the heterocycle of interest was carried out in two high-yielding steps. The hydrobromide salt of the isothiourea of interest provided suitable crystals for X-ray diffraction analysis, the results of which are reported. Salient observations from this analysis are the near perpendicular arrangement of the phenyl ring and the mean plane of the heterocycle. This conformational characteristic may be relevant with regard the stereoselectivity induced by the chiral isothiourea in asymmetric reactions. Furthermore, evidence was found for the existence of an S...Br− halogen bond. Full Article text
el Analytical models representing X-ray form factors of ions By journals.iucr.org Published On :: 2024-01-01 Parameters in analytical models for X-ray form factors of ions f0(s), based on the inverse Mott–Bethe formula involving a variable number of Gaussians, are determined for a wide range of published data sets {s, f0(s)}. The models reproduce the calculated form-factor values close to what is expected from a uniform statistical distribution with limits determined by their precision. For different ions associated with the same atom, the number of Gaussians in the models decreases with increasing net positive charge. Full Article text
el Modelling dynamical 3D electron diffraction intensities. I. A scattering cluster algorithm By journals.iucr.org Published On :: 2024-01-25 Three-dimensional electron diffraction (3D-ED) is a powerful technique for crystallographic characterization of nanometre-sized crystals that are too small for X-ray diffraction. For accurate crystal structure refinement, however, it is important that the Bragg diffracted intensities are treated dynamically. Bloch wave simulations are often used in 3D-ED, but can be computationally expensive for large unit cell crystals due to the large number of diffracted beams. Proposed here is an alternative method, the `scattering cluster algorithm' (SCA), that replaces the eigen-decomposition operation in Bloch waves with a simpler matrix multiplication. The underlying principle of SCA is that the intensity of a given Bragg reflection is largely determined by intensity transfer (i.e. `scattering') from a cluster of neighbouring diffracted beams. However, the penalty for using matrix multiplication is that the sample must be divided into a series of thin slices and the diffracted beams calculated iteratively, similar to the multislice approach. Therefore, SCA is more suitable for thin specimens. The accuracy and speed of SCA are demonstrated on tri-isopropyl silane (TIPS) pentacene and rubrene, two exemplar organic materials with large unit cells. Full Article text
el Modelling dynamical 3D electron diffraction intensities. II. The role of inelastic scattering By journals.iucr.org Published On :: 2024-01-25 The strong interaction of high-energy electrons with a crystal results in both dynamical elastic scattering and inelastic events, particularly phonon and plasmon excitation, which have relatively large cross sections. For accurate crystal structure refinement it is therefore important to uncover the impact of inelastic scattering on the Bragg beam intensities. Here a combined Bloch wave–Monte Carlo method is used to simulate phonon and plasmon scattering in crystals. The simulated thermal and plasmon diffuse scattering are consistent with experimental results. The simulations also confirm the empirical observation of a weaker unscattered beam intensity with increasing energy loss in the low-loss regime, while the Bragg-diffracted beam intensities do not change significantly. The beam intensities include the diffuse scattered background and have been normalized to adjust for the inelastic scattering cross section. It is speculated that the random azimuthal scattering angle during inelastic events transfers part of the unscattered beam intensity to the inner Bragg reflections. Inelastic scattering should not significantly influence crystal structure refinement, provided there are no artefacts from any background subtraction, since the relative intensity of the diffracted beams (which includes the diffuse scattering) remains approximately constant in the low energy loss regime. Full Article text
el Parameterized absorptive electron scattering factors By journals.iucr.org Published On :: 2024-01-25 In electron diffraction, thermal atomic motion produces incoherent scattering over a relatively wide angular range, which appears as a diffuse background that is usually subtracted from measurements of Bragg spot intensities in structure solution methods. The transfer of electron flux from Bragg spots to diffuse scatter is modelled using complex scattering factors f + if' in the Bloch wave methodology. In a two-beam Einstein model the imaginary `absorptive' scattering factor f' can be obtained by the evaluation of an integral containing f over all possible scattering angles. While more sophisticated models of diffuse scatter are widely used in the electron microscopy community, it is argued in this paper that this simple model is appropriate for current structure solution and refinement methods. The two-beam model is a straightforward numerical calculation, but even this simplistic approach can become time consuming for simulations of materials with large numbers of atoms in the unit cell and/or many incident beam orientations. Here, a parameterized form of f' is provided for 103 elements as neutral, spherical atoms that reduces calculation time considerably. Full Article text
el Automated selection of nanoparticle models for small-angle X-ray scattering data analysis using machine learning By journals.iucr.org Published On :: 2024-02-29 Small-angle X-ray scattering (SAXS) is widely used to analyze the shape and size of nanoparticles in solution. A multitude of models, describing the SAXS intensity resulting from nanoparticles of various shapes, have been developed by the scientific community and are used for data analysis. Choosing the optimal model is a crucial step in data analysis, which can be difficult and time-consuming, especially for non-expert users. An algorithm is proposed, based on machine learning, representation learning and SAXS-specific preprocessing methods, which instantly selects the nanoparticle model best suited to describe SAXS data. The different algorithms compared are trained and evaluated on a simulated database. This database includes 75 000 scattering spectra from nine nanoparticle models, and realistically simulates two distinct device configurations. It will be made freely available to serve as a basis of comparison for future work. Deploying a universal solution for automatic nanoparticle model selection is a challenge made more difficult by the diversity of SAXS instruments and their flexible settings. The poor transferability of classification rules learned on one device configuration to another is highlighted. It is shown that training on several device configurations enables the algorithm to be generalized, without degrading performance compared with configuration-specific training. Finally, the classification algorithm is evaluated on a real data set obtained by performing SAXS experiments on nanoparticles for each of the instrumental configurations, which have been characterized by transmission electron microscopy. This data set, although very limited, allows estimation of the transferability of the classification rules learned on simulated data to real data. Full Article text
el N-representable one-electron reduced density matrix reconstruction with frozen core electrons By journals.iucr.org Published On :: 2024-03-21 Recent advances in quantum crystallography have shown that, beyond conventional charge density refinement, a one-electron reduced density matrix (1-RDM) satisfying N-representability conditions can be reconstructed using jointly experimental X-ray structure factors and directional Compton profiles (DCP) through semidefinite programming. So far, such reconstruction methods for 1-RDM, not constrained to idempotency, have been tested only on a toy model system (CO2). In this work, a new method is assessed on crystalline urea [CO(NH2)2] using static (0 K) and dynamic (50 K) artificial experimental data. An improved model, including symmetry constraints and frozen core-electron contribution, is introduced to better handle the increasing system complexity. Reconstructed 1-RDMs, deformation densities and DCP anisotropy are analysed, and it is demonstrated that the changes in the model significantly improve the reconstruction quality, even when there is insufficient information and data corruption. The robustness of the model and the strategy are thus shown to be well adapted to address the reconstruction problem from actual experimental scattering data. Full Article text
el Permissible domain walls in monoclinic ferroelectrics. Part II. The case of MC phases By journals.iucr.org Published On :: 2024-04-29 Monoclinic ferroelectric phases are prevalent in various functional materials, most notably mixed-ion perovskite oxides. These phases can manifest as regularly ordered long-range crystallographic structures or as macroscopic averages of the self-assembled tetragonal/rhombohedral nanodomains. The structural and physical properties of monoclinic ferroelectric phases play a pivotal role when exploring the interplay between ferroelectricity, ferroelasticity, giant piezoelectricity and multiferroicity in crystals, ceramics and epitaxial thin films. However, the complex nature of this subject presents challenges, particularly in deciphering the microstructures of monoclinic domains. In Paper I [Biran & Gorfman (2024). Acta Cryst. A80, 112–128] the geometrical principles governing the connection of domain microstructures formed by pairing MAB type monoclinic domains were elucidated. Specifically, a catalog was established of `permissible domain walls', where `permissible', as originally introduced by Fousek & Janovec [J. Appl. Phys. (1969), 40, 135–142], denotes a mismatch-free connection between two monoclinic domains along the corresponding domain wall. The present article continues the prior work by elaborating on the formalisms of permissible domain walls to describe domain microstructures formed by pairing the MC type monoclinic domains. Similarly to Paper I, 84 permissible domain walls are presented for MC type domains. Each permissible domain wall is characterized by Miller indices, the transformation matrix between the crystallographic basis vectors of the domains and, crucially, the expected separation of Bragg peaks diffracted from the matched pair of domains. All these parameters are provided in an analytical form for easy and intuitive interpretation of the results. Additionally, 2D illustrations are provided for selected instances of permissible domain walls. The findings can prove valuable for various domain-related calculations, investigations involving X-ray diffraction for domain analysis and the description of domain-related physical properties. Full Article text
el Structure of the outer membrane porin OmpW from the pervasive pathogen Klebsiella pneumoniae By journals.iucr.org Published On :: 2024-01-01 Conjugation is the process by which plasmids, including those that carry antibiotic-resistance genes, are mobilized from one bacterium (the donor) to another (the recipient). The conjugation efficiency of IncF-like plasmids relies on the formation of mating-pair stabilization via intimate interactions between outer membrane proteins on the donor (a plasmid-encoded TraN isoform) and recipient bacteria. Conjugation of the R100-1 plasmid into Escherichia coli and Klebsiella pneumoniae (KP) recipients relies on pairing between the plasmid-encoded TraNα in the donor and OmpW in the recipient. Here, the crystal structure of K. pneumoniae OmpW (OmpWKP) is reported at 3.2 Å resolution. OmpWKP forms an eight-stranded β-barrel flanked by extracellular loops. The structures of E. coli OmpW (OmpWEC) and OmpWKP show high conservation despite sequence variability in the extracellular loops. Full Article text
el Crystal structure of the RNA-recognition motif of Drosophila melanogaster tRNA (uracil-5-)-methyltransferase homolog A By journals.iucr.org Published On :: 2024-01-25 Human tRNA (uracil-5-)-methyltransferase 2 homolog A (TRMT2A) is the dedicated enzyme for the methylation of uridine 54 in transfer RNA (tRNA). Human TRMT2A has also been described as a modifier of polyglutamine (polyQ)-derived neuronal toxicity. The corresponding human polyQ pathologies include Huntington's disease and constitute a family of devastating neurodegenerative diseases. A polyQ tract in the corresponding disease-linked protein causes neuronal death and symptoms such as impaired motor function, as well as cognitive impairment. In polyQ disease models, silencing of TRMT2A reduced polyQ-associated cell death and polyQ protein aggregation, suggesting this protein as a valid drug target against this class of disorders. In this paper, the 1.6 Å resolution crystal structure of the RNA-recognition motif (RRM) from Drosophila melanogaster, which is a homolog of human TRMT2A, is described and analysed. Full Article text
el Preliminary X-ray diffraction and ligand-binding analyses of the N-terminal domain of hypothetical protein Rv1421 from Mycobacterium tuberculosis H37Rv By journals.iucr.org Published On :: 2024-06-27 Mycobacterium tuberculosis can reside and persist in deep tissues; latent tuberculosis can evade immune detection and has a unique mechanism to convert it into active disease through reactivation. M. tuberculosis Rv1421 (MtRv1421) is a hypothetical protein that has been proposed to be involved in nucleotide binding-related metabolism in cell-growth and cell-division processes. However, due to a lack of structural information, the detailed function of MtRv1421 remains unclear. In this study, a truncated N-terminal domain (NTD) of MtRv1421, which contains a Walker A/B-like motif, was purified and crystallized using PEG 400 as a precipitant. The crystal of MtRv1421-NTD diffracted to a resolution of 1.7 Å and was considered to belong to either the C-centered monoclinic space group C2 or the I-centered orthorhombic space group I222, with unit-cell parameters a = 124.01, b = 58.55, c = 84.87 Å, β = 133.12° or a = 58.53, b = 84.86, c = 90.52 Å, respectively. The asymmetric units of the C2 or I222 crystals contained two or one monomers, respectively. In terms of the binding ability of MtRv1421-NTD to various ligands, uridine diphosphate (UDP) and UDP-N-acetylglucosamine significantly increased the melting temperature of MtRv1421-NTD, which indicates structural stabilization through the binding of these ligands. Altogether, the results reveal that a UDP moiety may be required for the interaction of MtRv1421-NTD as a nucleotide-binding protein with its ligand. Full Article text
el Structures of Brucella ovis leucine-, isoleucine-, valine-, threonine- and alanine-binding protein reveal a conformationally flexible peptide-binding cavity By journals.iucr.org Published On :: 2024-08-23 Brucella ovis is an etiologic agent of ovine epididymitis and brucellosis that causes global devastation in sheep, rams, goats, small ruminants and deer. There are no cost-effective methods for the worldwide eradication of ovine brucellosis. B. ovis and other protein targets from various Brucella species are currently in the pipeline for high-throughput structural analysis at the Seattle Structural Genomics Center for Infectious Disease (SSGCID), with the aim of identifying new therapeutic targets. Furthermore, the wealth of structures generated are effective tools for teaching scientific communication, structural science and biochemistry. One of these structures, B. ovis leucine-, isoleucine-, valine-, threonine- and alanine-binding protein (BoLBP), is a putative periplasmic amino acid-binding protein. BoLBP shares less than 29% sequence identity with any other structure in the Protein Data Bank. The production, crystallization and high-resolution structures of BoLBP are reported. BoLBP is a prototypical bacterial periplasmic amino acid-binding protein with the characteristic Venus flytrap topology of two globular domains encapsulating a large central cavity containing the peptide-binding region. The central cavity contains small molecules usurped from the crystallization milieu. The reported structures reveal the conformational flexibility of the central cavity in the absence of bound peptides. The structural similarity to other LBPs can be exploited to accelerate drug repurposing. Full Article text
el Glucose-6-phosphate dehydrogenase and its 3D structures from crystallography and electron cryo-microscopy By journals.iucr.org Published On :: 2024-09-11 Glucose-6-phosphate dehydrogenase (G6PD) is the first enzyme in the pentose phosphate pathway. It has been extensively studied by biochemical and structural techniques. 13 X-ray crystal structures and five electron cryo-microscopy structures in the PDB are focused on in this topical review. Two F420-dependent glucose-6-phosphate dehydrogenase (FGD) structures are also reported. The significant differences between human and parasite G6PDs can be exploited to find selective drugs against infections such as malaria and leishmaniasis. Furthermore, G6PD is a prognostic marker in several cancer types and is also considered to be a tumour target. On the other hand, FGD is considered to be a target against Mycobacterium tuberculosis and possesses a high biotechnological potential in biocatalysis and bioremediation. Full Article text
el X-ray crystal structure of proliferating cell nuclear antigen 1 from Aeropyrum pernix By journals.iucr.org Published On :: 2024-10-09 Proliferating cell nuclear antigen (PCNA) plays a critical role in DNA replication by enhancing the activity of various proteins involved in replication. In this study, the crystal structure of ApePCNA1, one of three PCNAs from the thermophilic archaeon Aeropyrum pernix, was elucidated. ApePCNA1 was cloned and expressed in Escherichia coli and the protein was purified and crystallized. The resulting crystal structure determined at 2.00 Å resolution revealed that ApePCNA1 does not form a trimeric ring, unlike PCNAs from other domains of life. It has unique structural features, including a long interdomain-connecting loop and a PIP-box-like sequence at the N-terminus, indicating potential interactions with other proteins. These findings provide insights into the functional mechanisms of PCNAs in archaea and their evolutionary conservation across different domains of life. A modified medium and protocol were used to express recombinant protein containing the lac operon. The expression of the target protein increased and the total incubation time decreased when using this system compared with those of previous expression protocols. Full Article text