106,867 results match your criteria x-ray crystallography

Synthesis, characterization of ruthenium(II), nickel(II), palladium(II), and platinum(II) triphenylphosphine-based complexes bearing an ONS-donor chelating agent: Interaction with biomolecules, antioxidant, in vitro cytotoxic, apoptotic activity and cell cycle analysis.

J Inorg Biochem 2021 Jul 21;223:111549. Epub 2021 Jul 21.

Chemistry Department, Faculty of Science, Damietta University, New Damietta 34517, Egypt. Electronic address:

Four new transition metal complexes, [M(PPh)(L)]CHOH (M = Ni(II) (1), Pd(II) (2)) [Pt (PPh)(HL)]Cl (3) and [Ru(CO)(PPh)(L)] (4) (HL = 2,4-dihydroxybenzaldehyde-S-methyldithiocarbazate, PPh = triphenylphosphine) have been synthesized and characterized by elemental analyses (C, H, N), FTIR, NMR (H, P), ESI-MS and UV-visible spectroscopy. The molecular structure of (1) and (2) complexes was confirmed by single-crystal X-ray crystallography. It showed a distorted square planar geometry for both complexes around the metal center, and the HL adopt a bi-negative tridentate chelating mode. Read More

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Unexpected identification of a bupivacaine analog from smuggling by using single-crystal X-ray diffraction analysis: N-(2,6-dimethylphenyl)-1-phenethylpiperidine-2-carboxamide.

Forensic Sci Int 2021 Jul 22;326:110917. Epub 2021 Jul 22.

Department of Forensic Science, Investigation Bureau, Ministry of Justice, Xindian Dist, New Taipei City 231209, Taiwan.

The identification of new psychoactive substances (NPSs) is essential against drug abuse, especially for "new" drugs that are not regulated by international drug conventions. A suspicious powder seized by the officers of Taipei Customs Administration of Taiwan was sent to this laboratory for analysis by using gas chromatography-mass spectrometry (GCMS), liquid chromatography-high resolution mass spectrometry (LCHRMS), proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR) with distortionless enhancement by polarization transfer (DEPT) at proton pulses of 45°, 90°, and 135°, two-dimensional correlation NMR measurements (2D_COSY), and heteronuclear single-quantum correlation NMR measurements (2D_HSQC). However, the structure of this "unknown" sample was difficult to identify. Read More

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The Induction Mechanism of the Flavonoid-Responsive Regulator FrrA.

FEBS J 2021 Jul 27. Epub 2021 Jul 27.

Institute for Biochemistry, Dept. Molecular Structural Biology, University of Greifswald, Greifswald, Germany.

Bradyrhizobium diazoefficiens, a bacterial symbiont of soybean and other leguminous plants, enters a nodulation-promoting genetic programme in the presence of host-produced flavonoids and related signalling compounds. Here, we describe the crystal structure of an isoflavonoid-responsive regulator (FrrA) from Bradyrhizobium, as well as co-crystal structures with inducing and non-inducing ligands (genistein and naringenin, respectively). The structures reveal a TetR-like fold whose DNA-binding domain is capable of adopting a range of orientations. Read More

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Efficient entropy-driven inhibition of dipeptidyl peptidase III by hydroxyethylene transition state peptidomimetics.

Chemistry 2021 Jul 27. Epub 2021 Jul 27.

Graz University of Technology: Technische Universitat Graz, Institute of Biochemistry, AUSTRIA.

Dipeptidyl peptidase III (DPP3) is a ubiquitously expressed Zn-dependent protease, which plays an important role in regulating endogenous peptide hormones, such as enkephalins or angiotensins. In previous biophysical studies, we could show that substrate binding is driven by a large entropic contribution due to the release of water molecules from the closing binding cleft. Here, we report the design, synthesis and biophysical characterization of peptidomimetic inhibitors using for the first time an hydroxyethylene transition-state mimetic for a metalloprotease. Read More

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BonA from Forms a Divisome-Localized Decamer That Supports Outer Envelope Function.

mBio 2021 Jul 27:e0148021. Epub 2021 Jul 27.

Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash Universitygrid.1002.3, Clayton, Australia.

Acinetobacter baumannii is a high-risk pathogen due to the rapid global spread of multidrug-resistant lineages. Its phylogenetic divergence from other ESKAPE pathogens means that determinants of its antimicrobial resistance can be difficult to extrapolate from other widely studied bacteria. A recent study showed that A. Read More

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Enantioenriched Ruthenium-Tris-Bipyridine Complexes Bearing One Helical Bipyridine Ligand: Access to Fused Multihelicenic Systems and Chiroptical Redox Switches.

Inorg Chem 2021 Jul 23. Epub 2021 Jul 23.

Univ Rennes CNRS, , ISCR-UMR 6226 ScanMat-UMS 2001, 35000 Rennes, France.

The synthesis and photophysical and chiroptical properties of novel aza[]helicenes (-, ,, = 4-7) substituted with one or two 2-pyridyl groups are described. The preparation was performed via an adapted Mallory reaction using aromatic imines as precursors. The obtained novel class of helical 2,2'-bipyridine ligands was then coordinated to Ru(bipy) units, thus affording the first diastereomerically and enantiomerically pure [RuL(bipy)] (,, L = ,) or [RuL'(bipy)] (, L' = ) complexes. Read More

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The Story of 5d Metallocorroles: From Metal-Ligand Misfits to New Building Blocks for Cancer Phototherapeutics.

Acc Chem Res 2021 Jul 23. Epub 2021 Jul 23.

Department of Chemistry, UiT-The Arctic University of Norway, N-9037 Tromso, Norway.

ConspectusPorphyrin chemistry is Shakespearean: over a century of study has not withered the field's apparently infinite variety. Heme proteins continually astonish us with novel molecular mechanisms, while new porphyrin analogues bowl us over with unprecedented optical, electronic, and metal-binding properties. Within the latter domain, corroles occupy a special place, exhibiting a unique and rich coordination chemistry. Read More

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An on-demand, drop-on-drop method for studying enzyme catalysis by serial crystallography.

Nat Commun 2021 07 22;12(1):4461. Epub 2021 Jul 22.

Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.

Serial femtosecond crystallography has opened up many new opportunities in structural biology. In recent years, several approaches employing light-inducible systems have emerged to enable time-resolved experiments that reveal protein dynamics at high atomic and temporal resolutions. However, very few enzymes are light-dependent, whereas macromolecules requiring ligand diffusion into an active site are ubiquitous. Read More

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Protocol on synthesis and characterization of copper-doped InP/ZnSe quantum dots as ecofriendly luminescent solar concentrators with high performance and large area.

STAR Protoc 2021 Sep 9;2(3):100664. Epub 2021 Jul 9.

Department of Biomedical Science and Engineering, Koç University, Istanbul 34450, Turkey.

Luminescent solar concentrators (LSCs) are simple and cost-effective solar energy-harvesting devices. Indium phosphide (InP)-based colloidal quantum dots (QDs) are promising QDs for efficient LSC devices due to their environmentally benign nature. One major challenge in LSC devices is reabsorption losses. Read More

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September 2021

New Reactions of Contraction of the -Quinone Ring with the Formation of Derivatives of 2-(2-Indolyl)-cyclopenta[b]pyrrole-3,4-diones and Pyrindino[1,2-a]indoles: A Combined Experimental and Density Functional Theory Investigation.

ACS Omega 2021 Jul 8;6(28):18226-18234. Epub 2021 Jul 8.

Southern Scientific Center of Russian Academy of Science, 141, Chekhova Str., Rostov on Don 344006, Russia.

Derivatives of 2-(2-indolyl)-cyclopenta[b]pyrrole-3,4-diones and pyrindino[1,2-a]indoles were synthesized by a new reaction of contraction of the -quinone ring, and their structures were investigated by X-ray crystallography and nuclear magnetic resonance spectroscopy. The mechanisms of the reactions were suggested based on density functional theory calculations of the critical parts of the potential energy surfaces. Read More

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Cavity-Containing [FeL] Helicates: An Examination of Host-Guest Chemistry and Cytotoxicity.

Front Chem 2021 7;9:697684. Epub 2021 Jul 7.

Department of Chemistry, University of Otago, Dunedin, New Zealand.

Two new di(2,2'-bipyridine) ligands, 2,6-bis([2,2'-bipyridin]-5-ylethynyl)pyridine () and bis(4-([2,2'-bipyridin]-5-ylethynyl)phenyl)methane () were synthesized and used to generate two metallosupramolecular [Fe()](BF) cylinders. The ligands and cylinders were characterized using elemental analysis, electrospray ionization mass spectrometry, UV-vis, H-, C and DOSY nuclear magnetic resonance (NMR) spectroscopies. The molecular structures of the [Fe()](BF) cylinders were confirmed using X-ray crystallography. Read More

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Single-step Replacement of an Unreactive C-H Bond by a C-S Bond Using Polysulfide as the Direct Sulfur Source in Anaerobic Ergothioneine Biosynthesis.

ACS Catal 2020 Aug 16;10(16):8981-8994. Epub 2020 Jul 16.

Department of Chemistry, Boston University, Boston, MA 02215, USA.

Ergothioneine, a natural longevity vitamin and antioxidant, is a thiol-histidine derivative. Recently, two types of biosynthetic pathways were reported. In the aerobic ergothioneine biosynthesis, a non-heme iron enzyme incorporates a sulfoxide to an sp C-H bond in trimethyl-histidine (hercynine) through oxidation reactions. Read More

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Thermodynamic Description of Dilution and Dissolution Processes in the MgCl-CsCl-HO Ternary System.

Materials (Basel) 2021 Jul 20;14(14). Epub 2021 Jul 20.

Chemistry Institute, Saint Petersburg State University, 198504 Saint Petersburg, Russia.

Thermodynamic data on the properties of the water-based electrolyte systems are very valuable for fundamental physical chemistry and for industrial applications. The missing data both on the dilution and dissolution enthalpies for the ternary CsCl-MgCl-HO mixed electrolyte system were investigated by means of the calorimetry method. The dilution calorimetry was performed at 298 K for the set of solutions from diluted to concentrated at constant ratio Cs/Mg=1. Read More

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Crystal Structure-Guided Design of Bisubstrate Inhibitors and Photoluminescent Probes for Protein Kinases of the PIM Family.

Molecules 2021 Jul 19;26(14). Epub 2021 Jul 19.

Institute of Chemistry, University of Tartu, 14A Ravila St., 50411 Tartu, Estonia.

We performed an X-ray crystallographic study of complexes of protein kinase PIM-1 with three inhibitors comprising an adenosine mimetic moiety, a linker, and a peptide-mimetic (d-Arg) fragment. Guided by the structural models, simplified chemical structures with a reduced number of polar groups and chiral centers were designed. The developed inhibitors retained low-nanomolar potency and possessed remarkable selectivity toward the PIM kinases. Read More

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Synthesis, Characterization, and Non-Covalent Interactions of Palladium(II)-Amino Acid Complexes.

Molecules 2021 Jul 17;26(14). Epub 2021 Jul 17.

Department of Chemistry, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA.

The reaction of palladium(II) acetate with acyclic amino acids in acetone/water yields square planar bis-chelated palladium amino acid complexes that exhibit interesting non-covalent interactions. In all cases, complexes were examined by multiple spectroscopic techniques, especially HRMS (high resolution mass spectrometry), IR (infrared spectroscopy), and H NMR (nuclear magnetic resonance) spectroscopy. In some cases, suitable crystals for single crystal X-ray diffraction were able to be grown and the molecular structure was obtained. Read More

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Mono- and Dinitro-BN-Naphthalenes: Formation and Characterization.

Molecules 2021 Jul 11;26(14). Epub 2021 Jul 11.

Naval Research Laboratory, 4555 Overlook Ave, Washington, DC 20375, USA.

Mono- and dinitro-BN-naphthalenes, i.e., 1-nitro-, 3-nitro-, 1,6-dinitro-, 3,6-dinitro-, and 1,8-dinitro-BNN, were generated in the nitration of 9,10-BN-naphthalene (BNN), a boron-nitrogen (BN) bond-embedded naphthalene, with AcONO and NOBF in acetonitrile. Read More

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Synthesis and In Vitro Evaluation of C-7 and C-8 Luteolin Derivatives as Influenza Endonuclease Inhibitors.

Int J Mol Sci 2021 Jul 20;22(14). Epub 2021 Jul 20.

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Gilead Sciences and IOCB Research Center, Flemingovo n. 2, 166 10 Prague, Czech Republic.

The part of the influenza polymerase PA subunit featuring endonuclease activity is a target for anti-influenza therapies, including the FDA-approved drug Xofluza. A general feature of endonuclease inhibitors is their ability to chelate Mg or Mn ions located in the enzyme's catalytic site. Previously, we screened a panel of flavonoids for PA inhibition and found luteolin and its C-glucoside orientin to be potent inhibitors. Read More

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Comprehensive Evaluation of Biological Effects of Pentathiepins on Various Human Cancer Cell Lines and Insights into Their Mode of Action.

Int J Mol Sci 2021 Jul 16;22(14). Epub 2021 Jul 16.

Pharmazeutische/Medizinische Chemie, Institut für Pharmazie, Universität Greifswald, 17489 Greifswald, Germany.

Pentathiepins are polysulfur-containing compounds that exert antiproliferative and cytotoxic activity in cancer cells, induce oxidative stress and apoptosis, and inhibit glutathione peroxidase (GPx1). This renders them promising candidates for anticancer drug development. However, the biological effects and how they intertwine have not yet been systematically assessed in diverse cancer cell lines. Read More

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Structural and biophysical characterization of the Burkholderia pseudomallei IspF inhibitor L-tryptophan hydroxamate.

Bioorg Med Chem Lett 2021 Jul 21;48:128273. Epub 2021 Jul 21.

Department of Chemistry and Biochemistry, Northern Illinois University, 1425 W. Lincoln Hwy., DeKalb, IL 60115, USA. Electronic address:

The enzyme 2-methylerythritol 2,4-cyclodiphosphate synthase, IspF, is essential for the biosynthesis of isoprenoids in most bacteria, some eukaryotic parasites, and the plastids of plant cells. The development of inhibitors that target IspF may lead to novel classes of anti-infective agents or herbicides. Enantiomers of tryptophan hydroxamate were synthesized and evaluated for binding to Burkholderia pseudomallei (Bp) IspF. Read More

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Molecular mechanism of quorum sensing inhibition in Streptococcus by the phage protein paratox.

J Biol Chem 2021 Jul 20:100992. Epub 2021 Jul 20.

Department of Microbiology, University of Manitoba, Winnipeg, MB R3T 2N2 Canada. Electronic address:

Streptococcus pyogenes, or Group A Streptococcus, is a Gram-positive bacterium that can be both a human commensal and pathogen. Central to this dichotomy are temperate bacteriophages that incorporate into the bacterial genome as a prophage. These genetic elements encode both the phage proteins and the toxins harmful to the human host. Read More

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Crystal structure and functional characterization of an oligosaccharide dehydrogenase from Pycnoporus cinnabarinus provides insights into fungal breakdown of lignocellulose.

Biotechnol Biofuels 2021 Jul 22;14(1):161. Epub 2021 Jul 22.

INRAE, Aix Marseille Université, BBF UMR1163 Biodiversité et Biotechnologie Fongiques, 163 Avenue de Luminy, 13009, Marseille, France.

Background: Fungal glucose dehydrogenases (GDHs) are FAD-dependent enzymes belonging to the glucose-methanol-choline oxidoreductase superfamily. These enzymes are classified in the "Auxiliary Activity" family 3 (AA3) of the Carbohydrate-Active enZymes database, and more specifically in subfamily AA3_2, that also includes the closely related flavoenzymes aryl-alcohol oxidase and glucose 1-oxidase. Based on sequence similarity to known fungal GDHs, an AA3_2 enzyme active on glucose was identified in the genome of Pycnoporus cinnabarinus, a model Basidiomycete able to completely degrade lignin. Read More

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After 200 years: the structure of bleach and characterization of hypohalite ions by single-crystal X-ray diffraction.

Angew Chem Int Ed Engl 2021 Jul 22. Epub 2021 Jul 22.

McGill University, Chemistry, 801 Sherbrooke St. W., H3A 0B8, Montreal, CANADA.

We report the first X-ray single crystal structures of hypochlorite (ClO - ) and hypobromite (BrO - ) salts, including hydrated sodium hypochlorite - a staple of the chlorine industry and ubiquitous bleaching and disinfection agent for almost 200 years. The structures, supported by variable-temperature Raman spectroscopy on individual crystals and periodic density-functional theory (DFT) calculations, provide insight into solid-state geometry and supramolecular chemistry of hypohalite ions. Read More

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Canopy Catalysts for Alkyne Metathesis: Investigations into a Bimolecular Decomposition Pathway and the Stability of the Podand Cap.

Chemistry 2021 Jul 22. Epub 2021 Jul 22.

Max-Planck-Institut fur Kohlenforschung, Organometallic Chemistry, GERMANY.

Molybdenum alkylidyne complexes with a trisilanolate podand ligand framework ("canopy catalysts") are the arguably most selective catalysts for alkyne metathesis known to date. Among them, complex 1a endowed with a fence of lateral methyl substituents on the silicon linkers is most reactive, although fairly high loadings are required in certain applications. It is now shown that this catalyst decomposes readily via a bimolecular pathway, which engages the MoºCR entities in a stoichiometric triple bond metathesis event to furnish RCºCR and the corresponding dinuclear complex 8 with a MoºMo core. Read More

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Discovery of IACS-9779 and IACS-70465 as Potent Inhibitors Targeting Indoleamine 2,3-Dioxygenase 1 (IDO1) Apoenzyme.

J Med Chem 2021 Jul 22. Epub 2021 Jul 22.

IACS (Institute for Applied Cancer Science), University of Texas, MD Anderson Cancer Center, 1881 East Road, Houston, Texas 77054, United States.

Indoleamine 2,3-dioxygenase 1 (IDO1), a heme-containing enzyme that mediates the rate-limiting step in the metabolism of l-tryptophan to kynurenine, has been widely explored as a potential immunotherapeutic target in oncology. We developed a class of inhibitors with a conformationally constrained bicyclo[3.1. Read More

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First Synthesis of the Inherently Chiral Trans-4' Bisadduct of C59N Azafullerene Using Cyclo-[2]-dodecylmalonate as Tether.

Chemistry 2021 Jul 22. Epub 2021 Jul 22.

University of Cyprus, Department of Chemistry, University Str.1, Building no.13, 2109, Nicosia, CYPRUS.

Multiaddition chemistry of azafullerene C 59 N has been scarcely explored and the isolation of pure bisadducts is in its infancy. Encouraged by the recent regioselective synthesis of the inherently chiral equatorial face bisadduct of C 59 N, we focused on the isolation of the first trans- 4 bisadduct, via a simple two-step approach. The first regioselective synthesis of the trans- 4 bisadduct of C 59 N utilizing cyclo- [2]-dodecylmalonate as tether is now reported. Read More

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Sulfatides are endogenous ligands for the TLR4-MD-2 complex.

Proc Natl Acad Sci U S A 2021 Jul;118(30)

Center for the Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX 75390;

Many endogenous molecules, mostly proteins, purportedly activate the Toll-like receptor 4 (TLR4)-myeloid differentiation factor-2 (MD-2) complex, the innate immune receptor for lipopolysaccharide (LPS) derived from gram-negative bacteria. However, there is no structural evidence supporting direct TLR4-MD-2 activation by endogenous ligands. Sulfatides (3--sulfogalactosylceramides) are natural, abundant sulfated glycolipids that have variously been shown to initiate or suppress inflammatory responses. Read More

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Large-scale ratcheting in a bacterial DEAH/RHA-type RNA helicase that modulates antibiotics susceptibility.

Proc Natl Acad Sci U S A 2021 Jul;118(30)

Laboratory of Structural Biochemistry, Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany;

Many bacteria harbor RNA-dependent nucleoside-triphosphatases of the DEAH/RHA family, whose molecular mechanisms and cellular functions are poorly understood. Here, we show that the DEAH/RHA protein, HrpA, is an ATP-dependent 3 to 5' RNA helicase and that the RNA helicase activity of HrpA influences bacterial survival under antibiotics treatment. Limited proteolysis, crystal structure analysis, and functional assays showed that HrpA contains an N-terminal DEAH/RHA helicase cassette preceded by a unique N-terminal domain and followed by a large C-terminal region that modulates the helicase activity. Read More

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Molecular insights into the endoperoxide formation by Fe(II)/α-KG-dependent oxygenase NvfI.

Nat Commun 2021 07 20;12(1):4417. Epub 2021 Jul 20.

Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.

Endoperoxide-containing natural products are a group of compounds with structurally unique cyclized peroxide moieties. Although numerous endoperoxide-containing compounds have been isolated, the biosynthesis of the endoperoxides remains unclear. NvfI from Aspergillus novofumigatus IBT 16806 is an endoperoxidase that catalyzes the formation of fumigatonoid A in the biosynthesis of novofumigatonin. Read More

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Masitinib is a broad coronavirus 3CL inhibitor that blocks replication of SARS-CoV-2.

Science 2021 Jul 20. Epub 2021 Jul 20.

Institut Pasteur, Viral Populations and Pathogenesis Unit, Centre National de la Recherche Scientifique UMR 3569, Paris, France.

There is an urgent need for antiviral agents that treat SARS-CoV-2 infection. We screened a library of 1,900 clinically safe drugs against OC43, a human beta-coronavirus that causes the common cold and evaluated the top hits against SARS-CoV-2. Twenty drugs significantly inhibited replication of both viruses in vitro. Read More

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Immunogenicity study of engineered ferritins with C- and N-terminus insertion of Epstein-Barr nuclear antigen 1 epitope.

Vaccine 2021 Jul 17. Epub 2021 Jul 17.

School of Chemical Engineering and Advanced Materials, Faculty of Engineering, Computer and Mathematical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia. Electronic address:

Human ferritin heavy chain, an example of a protein nanoparticle, has recently been used as a vaccine delivery platform. Human ferritin has advantages of uniform architecture, robust thermal and chemical stabilities, and good biocompatibility and biodegradation. There is however a lack of understanding about the relationship between insertion sites in ferritin (N-terminus and C-terminus) and the corresponding humoral and cell-mediated immune responses. Read More

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