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Sequence-Specific Recognition And Cooperative Dimerization Of N-Terminal Aromatic Peptides In Aqueous Solution By A Synthetic Host, Lisa M. Heitmann, Alexander B. Taylor, P John Hart, Adam R. Urbach Sep 2006

Sequence-Specific Recognition And Cooperative Dimerization Of N-Terminal Aromatic Peptides In Aqueous Solution By A Synthetic Host, Lisa M. Heitmann, Alexander B. Taylor, P John Hart, Adam R. Urbach

Chemistry Faculty Research

This article describes the selective recognition and noncovalent dimerization of N-terminal aromatic peptides in aqueous solution by the synthetic host compound, cucurbit[8]uril (Q8). Q8 is known to bind two aromatic guests simultaneously and, in the presence of methyl viologen, to recognize N-terminal tryptophan over internal and C-terminal sequence isomers. Here, the binding of Q8 to aromatic peptides in the absence of methyl viologen was studied by isothermal titration calorimetry (ITC), 1H NMR spectroscopy, and X-ray crystallography. The peptides studied were of sequence X-Gly-Gly, Gly-X-Gly, and Gly-Gly-X (X = Trp, Phe, Tyr, and His). Q8 selectively binds and dimerizes Trp-Gly-Gly …


Optimization Of A Ribosomal Structural Domain By Natural Selection, Corina Maeder, G. L. Conn, D. E. Draper May 2006

Optimization Of A Ribosomal Structural Domain By Natural Selection, Corina Maeder, G. L. Conn, D. E. Draper

Chemistry Faculty Research

A conserved, independently folding domain in the large ribosomal subunit consists of 58 nt of rRNA and a single protein, L11. The tertiary structure of an rRNA fragment carrying the Escherichia coli sequence is marginally stable in vitro but can be substantially stabilized by mutations found in other organisms. To distinguish between possible reasons why natural selection has not evolved a more stable rRNA structure in E. coli, mutations affecting the rRNA tertiary structure were assessed for their in vitro effects on rRNA stability and L11 affinity (in the context of an rRNA fragment) or in vivo effects on cell …


Tuning Supported Catalyst Reactivity With Dendrimer-Templated Pt-Cu Nanoparticles, Natalie N. Hoover, Bethany J. Auten, Bert D. Chandler Mar 2006

Tuning Supported Catalyst Reactivity With Dendrimer-Templated Pt-Cu Nanoparticles, Natalie N. Hoover, Bethany J. Auten, Bert D. Chandler

Chemistry Faculty Research

The effects of particle composition on heterogeneous catalysis were studied using dendrimer-encapsulated nanoparticles (DENs) as precursors to supported Pt-Cu catalysts. Bimetallic Pt-Cu DENs with varying Pt/Cu ratios were prepared in an anaerobic aqueous solution and deposited onto a high-purity commercial alumina support. The dendrimer template was then thermally removed to yield supported nanoparticle catalysts, which were studied with toluene hydrogenation and CO oxidation catalysis as well as infrared spectroscopy of adsorbed CO. Incorporating Cu into Pt nanoparticles had opposite effects on the two test reactions. Cu acted as a mild promoter for CO oxidation catalysis, and the promoting effect was …


1,1´-Diethyl-2,2´,3,3´,4,4´,5,5´-Octamethylferrocenium Tetracyanoethylenide, [Fe(C5etme4)2]+[Tcne]–, A Charge-Transfer Salt Magnetic Solid With A Novel Structural Motif, T. David Harris, Michael Castellani, Arnold L. Rheingold, William M. Reiff, Gordon T. Yee Jan 2006

1,1´-Diethyl-2,2´,3,3´,4,4´,5,5´-Octamethylferrocenium Tetracyanoethylenide, [Fe(C5etme4)2]+[Tcne]–, A Charge-Transfer Salt Magnetic Solid With A Novel Structural Motif, T. David Harris, Michael Castellani, Arnold L. Rheingold, William M. Reiff, Gordon T. Yee

Chemistry Faculty Research

1,1′-Diethyl-2,2′,3,3′,4,4′,5,5′-octamethylferrocene has been utilized as a one-electron donor in the synthesis of a tetracyanoethylene charge-transfer salt, [Fe(C5EtMe4)2]+[TCNE]. Structural characterization shows that it adopts an arrangement of anions and cations completely different from the usual π stacking seen in analogous decamethylferrocenium compounds. The TCNE radical sits along side of the ferrocene, nearly perpendicular to the planes of the C5 rings. The nearly square geometry of the TCNE anion creates disorder over two orientations. [Fe(C5EtMe4)2]+[TCNE] is a simple paramagnet exhibiting neither long-range …


Restoration Of Frequency-Dependent Depression Of The H-Reflex By Passive Exercise In Spinal Rats, N. B. Reese, R. D. Skinner, D. Mitchell, C. C. Yates, Christina B. Cooley, T. S. Kiser, E. E. García-Rill Jan 2006

Restoration Of Frequency-Dependent Depression Of The H-Reflex By Passive Exercise In Spinal Rats, N. B. Reese, R. D. Skinner, D. Mitchell, C. C. Yates, Christina B. Cooley, T. S. Kiser, E. E. García-Rill

Chemistry Faculty Research

Hyper-reflexia, measured as a decrease of low frequency-dependent depression of the H-reflex, is known to occur in both humans and animals after spinal cord injury (SCI). Previous studies have shown that passive exercise for 3 months could be used to restore low frequency-dependent depression of the H-reflex after SCI. To determine the effects of various periods of time on the ability of passive exercise to restore low frequency-dependent depression of the H-reflex. Spinal Cord Injury Mobilization Program of the Center for Translational Neuroscience, the research arm of the Jackson T Stephens Spine and Neuroscience Institute, Little Rock, AR, USA. Adult …