The matrix protein (M) of respiratory syncytial virus (RSV), the prototype viral member of the Pneumovirinae (family Paramyxoviridae, order Mononegavirales), has been crystallized and the structure determined to a resolution of 1.6 Å. The structure comprises 2 compact -rich domains connected by a relatively unstructured linker region. Due to the high degree of side-chain order in the structure, an extensive contiguous area of positive surface charge covering Ϸ600 Å 2 can be resolved. This unusually large patch of positive surface potential spans both domains and the linker, and provides a mechanism for driving the interaction of the protein with a negatively-charged membrane surface or other virion components such as the nucleocapsid. This patch is complemented by regions of high hydrophobicity and a striking planar arrangement of tyrosine residues encircling the C-terminal domain. Comparison of the RSV M sequence with other members of the Pneumovirinae shows that regions of divergence correspond to surface exposed loops in the M structure, with the majority of viral species-specific differences occurring in the N-terminal domain.CD ͉ crystal structure ͉ respiratory syncytial virus ͉ sequence alignment R espiratory syncytial virus (RSV) is the prototype member of the Pneumovirinae, a subfamily of the Paramyxoviridae (order Mononegavirales). Morphologically, the extracellular virion consists of a lipid bilayer envelope, within which are embedded 3 glycoproteins, 2 of which (F and G) are important in cell attachment and viral entry into target cells. The third, the SH protein, contributes to pathology in the host (1). Internally, virions contain helical nucleocapsids that consist of N protein tightly bound to the negative-sense nonsegmented genomic RNA. The nucleocapsid in turn is associated with components of the viral RNA-dependent RNA polymerase (L, P, M2-1, and M2-2 proteins), forming the holo-nucleocapsid (2-4). Between the holo-nucleocapsid and the outer envelope there is a layer of matrix protein (M), which is associated peripherally with the membrane (5). The other family members of the Mononegavirales (Rhabdoviridae, Filoviridae, and Bornaviridae) all subscribe to this basic arrangement of the virion, although the overall morphology can vary between the families. For example, Paramyxoviridae virions are pleiomorphic, whereas the Rhabdoviridae have a regular bullet shape structure, and the Filoviridae have a more filamentous shape. Extracellular RSV virions form by a budding process that occurs at the plasma membrane within specialized lipid domains (5, 6) and M appears to drive the final assembly process, which is the incorporation of the holo-nucleocapsid and initiation of the budding process (7,8). Before budding, there is a coordinated assembly of viral components; and it is evident that the glycoproteins and M proteins are important determinants of the location on the plasma membrane at which the virus buds (9). It is also possible that the interaction between M and the glycoproteins, possibly mediat...
Two series of related donor-acceptor conjugated dipolar, pseudo-quadrupolar (V-shaped) and octupolar molecular systems based on the p-dimesitylborylphenylethynylaniline core, namely 4-(4-dimesitylborylphenylethynyl)-N,N-dimethylaniline, 4-[4-(4-dimesitylborylphenylethynyl)phenylethynyl]-N,N-dimethylaniline, 4,4'-bis(4-dimesitylborylphenylethynyl)-N-n-butylcarbazole and tris[4-(4-dimesitylborylphenylethynyl)phenyl]amine, and on the E-p-dimesitylborylethenylaniline motif, namely E-4-dimesitylborylethenyl-N,N-di(4-tolyl)aniline, 4,4'-bis(E-dimesitylborylethenyl)-N-n-butylcarbazole and tris(E-4-dimesitylborylethenylphenyl)amine have been synthesized, by palladium catalyzed cross-coupling and hydroboration routes, respectively. Their absorption and emission maxima, fluorescence lifetimes and quantum yields have been obtained and their twophoton absorption spectra and two-photon absorption (TPA) cross-sections have been examined. Of these systems, the octupolar compound tris-(E-4-dimesitylborylethenylphenyl)amine has been shown to exhibit the largest two-photon absorption cross-section among the two series of ca. 1000 GM at 740 nm. Its TPA performance is comparable to those of other triphenylamine based octupoles of similar size. The combination of such large TPA cross-sections and high emission quantum yields up to 0.94 make these systems attractive for applications involving two-photon excited fluorescence (TPEF).
(2015) 'Monomer sequence control via living anionic copolymerization : synthesis of alternating, statistical, and telechelic copolymers and sequence analysis by MALDI ToF mass spectrometry. ', Macromolecules., 48 (3). pp. 610-628.Further information on publisher's website:Publisher's copyright statement:This document is the Accepted Manuscript version of a Published Work that appeared in nal form in Macromolecules, copyright c 2015 American Chemical Society after peer review and technical editing by the publisher. To access the nal edited and published work see http://dx.doi.org/10.1021/ma5016038. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. 3LE. United Kingdom ABSTRACT: Diphenylethylene (DPE) is a monomer which has attracted significant interest from both academia and industry. DPE can undergo (co)polymerization by living anionic polymerization but is incapable of forming a homopolymer due to steric hindrance. Herein the copolymerization of DPE and 1,1-bis(4-tert-butyldimethylsiloxyphenyl)ethylene (DPE-OSi)with styrene or butadiene is described in order to produce (functional) copolymers with controlled co-monomer sequences -either alternating or telechelic. The copolymer sequences are inherently controlled by relative reactivity ratios, which in turn can be tuned by both monomer structure and by the polarity of the polymerization solvent. The composition of the copolymers prepared in this study were analyzed by 1 H NMR spectroscopy and MALDI ToF 2 mass spectrometry, the latter offering a unique opportunity to demonstrate perfect alternating sequences and insight into other sequences such as telechelic polymers.
The design, synthesis and application of a nine-coordinate gadolinium(III)-containing spin label, [Gd.sTPATCN]-SL, for use in nanometer-distance measurement experiments by EPR spectroscopy is presented. The spin label links to cysteines via a short thioether tether and has a narrow central transition indicative of small zero-field splitting (ZFS). A protein homodimer, TRIM25cc, was selectively labeled with [Gd.sTPATCN]-SL (70%) and a nitroxide (30%) under mild conditions and measured using the double electron electron resonance (DEER) technique with both commercial Qband and home-built W-band spectrometers. The label shows great promise for increasing the sensitivity of DEER measurements through both its favorable relaxation parameters, and the large DEER modulation depth at both Q-and W-band for the inter-Gd(III) DEER measurement which, at 9%, is the largest recorded under these conditions.
Atmospheric pressure Solids Analysis Probe (ASAP) mass spectrometry has facilitated the ionisation of oligomers from low molecular weight synthetic polymers, poly(ethylene glycol) (PEG: M(n) = 1430) and poly(styrene) (PS: M(n) = 1770), directly from solids, providing a fast and efficient method of identification. Ion source conditions were evaluated and it was found that the key instrument parameter was the ion source desolvation temperature which, when set to 600 °C was sufficient to vapourise the heavier oligomers for ionisation. PS, a non-polar polymer that is very challenging to analyse by MALDI or ESI without the aid of metal salts to promote cationisation, was ionised promptly by ASAP resulting in the production of radical cations. A small degree of in-source dissociation could be eliminated by control of the instrument ion source voltages. The fragmentation observed through in-source dissociation could be duplicated in a controlled manner through Collision-Induced Dissociation (CID) of the radical cations. PEG, which preferentially ionises through adduction with alkali metal cations in MALDI and ESI, was observed as a protonated molecular ion by ASAP. In-source dissociation could not be eliminated entirely and the fragmentation observed resulted from cleavage of the C-C and C-O backbone bonds, as opposed to only C-O bond cleavage observed from tandem mass spectrometry.
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