The molecular structure of norbornene as determined by electron diffraction and microwave spectroscopy

The molecular structure of norbornene has been investigated in the gas phase by combining electron diffraction data with microwave spectroscopic rotational constants. The interatomic distances (r_g) and bond angles were obtained by applying a least squares program to the refined experimental molecular diffraction intensities. The CC bond length was found to be 1.336 ± 0.002 Å while the

) bond length was 1. 529 ± 0.007 Å. Other bond lengths and angles included (IUPAC numbering system was used for norbornene): C₁-C₆ = 1.550 ± 0.020 Å, C₁-C₇ = 1.566± 0.005 Å, C₅-C₆ = 1.556 ± 0.005 Å, C-H_ave. = 1.103 ± 0.003 Å, ∠C₁C₂C₄ = 95.3°. The dihedral angle between planes C₁C₂C₃C₄ and C₁C₆C₅C₄ is 110.8 ± 1.5° while that between C₁C₂C₃C₄ and C₁C₇C₄ is 122.3°. The moments of inertia calculated from ED structure are in good agreement with microwave spectroscopic values.     

The Structure of the Antibiotic Hedamycin. I. Chemical,Physical and Spectral Properties

Interpretation of the chemical and spectral (IR., UV., ¹H- and ¹³C-NMR.) properties of the antitumor antibiotic hedamycin (C₄₁H₅₀N₂O₁₁) suggests that the molecule contains a methyl substituted 1-hydroxyanthraquinone nucleus, an α, β-unsaturated ketone, two sugar-like tetrahydropyran rings ( 4 and 8 ) and an aliphatic chain 2 , presumably with an epoxy group (see the Scheme).     

DNA-templated self-assembly of protein and nanoparticle linear arrays

Self-assembling DNA tiling lattices represent a versatile system for nanoscale construction. Self-assembled DNA arrays provide an excellent template for spatially positioning other molecules with increased relative precision and programmability. Here we report an experiment using a linear array of DNA triple crossover tiles to controllably template the self-assembly of single-layer or double-layer linear arrays of streptavidin molecules and streptavidin-conjugated nanogold particles through biotin-streptavidin interaction. The organization of streptavidin and its conjugated gold nanoparticles into periodic arrays was visualized by atomic force microscopy and scanning electron microscopy.     

A peptide-derived strategy for specifically targeting the mitochondria and ER of cancer cells: a new approach in fighting cancer

An effective anti-cancer therapy should exclusively target cancer cells and trigger in them a broad spectrum of cell death pathways that will prevent avoidance. Here, we present a new approach in cancer therapy that specifically targets the mitochondria and ER of cancer cells. We developed a peptide derived from the flexible and transmembrane domains of the human protein NAF-1/CISD2. This peptide (NAF-1^44-67) specifically permeates through the plasma membranes of human epithelial breast cancer cells, abolishes their mitochondria and ER, and triggers cell death with characteristics of apoptosis, ferroptosis and necroptosis. In vivo analysis revealed that the peptide significantly decreases tumor growth in mice carrying xenograft human tumors. Computational simulations of cancer vs. normal cell membranes reveal that the specificity of the peptide to cancer cells is due to its selective recognition of their membrane composition. NAF-1^44-67 represents a promising anti-cancer lead compound that acts via a unique mechanism.

An effective anti-cancer therapy should exclusively target cancer cells and trigger in them a broad spectrum of cell death pathways that will prevent avoidance.     

Structural and Functional Analysis of the Pyridoxal Phosphate Homeostasis Protein YggS from Fusobacterium nucleatum

Pyridoxal 5′-phosphate (PLP) is the active form of vitamin B6, but it is highly reactive and poisonous in its free form. YggS is a PLP-binding protein found in bacteria and humans that mediates PLP homeostasis by delivering PLP to target enzymes or by performing a protective function. Several biochemical and structural studies of YggS have been reported, but the mechanism by which YggS recognizes PLP has not been fully elucidated. Here, we report a functional and structural analysis of YggS from Fusobacterium nucleatum (FnYggS). The PLP molecule could bind to native FnYggS, but no PLP binding was observed for selenomethionine (SeMet)-derivatized FnYggS. The crystal structure of FnYggS showed a type III TIM barrel fold, exhibiting structural homology with several other PLP-dependent enzymes. Although FnYggS exhibited low (<35%) amino acid sequence similarity with previously studied YggS proteins, its overall structure and PLP-binding site were highly conserved. In the PLP-binding site of FnYggS, the sulfate ion was coordinated by the conserved residues Ser201, Gly218, and Thr219, which were positioned to provide the binding moiety for the phosphate group of PLP. The mutagenesis study showed that the conserved Ser201 residue in FnYggS was the key residue for PLP binding. These results will expand the knowledge of the molecular properties and function of the YggS family.     

Synthesis and characterization of thermally crosslinkable hole‐transporting polymers for PLEDs

Two new thermally crosslinkable hole‐transporting polymers, X‐PTPA and X‐PCz, were synthesized via Yamamoto coupling reactions. The number‐averaged molecular weights (M_n) of X‐PTPA and X‐PCz were found to be 45,000 and 48,000, respectively, and therewith, polydispersity indices were of 1.8 and 1.7, respectively. Thermally crosslinked X‐PTPA and X‐PCz exhibit excellent solvent resistance and stable optoelectronic properties. The UV–visible maximum absorption peaks of X‐PTPA and X‐PCz in the thin film state are at 389 and 322 nm, respectively. The HOMO levels of X‐PTPA and X‐PCz are estimated to be ?5.27 and ?5.39 eV, respectively. Multilayered devices (ITO/crosslinked X‐PTPA or X‐PCz/SY‐PPV/LiF/Al) were fabricated with SY (SuperYellow) as the emitting layer. The maximum efficiency of the multilayered device with a crosslinked X‐PTPA layer is approximately three times higher than that of the device without a crosslinked X‐PTPA layer and much higher than that of the crosslinked X‐PCz device. This result can be explained by the observations that crosslinked X‐PTPA produces increased electron accumulation within the emitter, SY, and also efficient exciton formation due to improved charge balance. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5111–5117