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Full-Text Articles in Physical Sciences and Mathematics

H2 Oxidation Over Supported Au Nanoparticle Catalysts: Evidence For Heterolytic H2 Activation At The Metal-Support Interface, Todd N. Whittaker, K. B. Sravan Kumar, Christine Peterson, Meagan N. Pollock, L. C. Grabow, Bert D. Chandler Dec 2018

H2 Oxidation Over Supported Au Nanoparticle Catalysts: Evidence For Heterolytic H2 Activation At The Metal-Support Interface, Todd N. Whittaker, K. B. Sravan Kumar, Christine Peterson, Meagan N. Pollock, L. C. Grabow, Bert D. Chandler

Chemistry Faculty Research

Water adsorbed at the metal-support interface (MSI) plays an important role in multiple reactions. Due to its importance in CO preferential oxidation (PrOx), we examined H2 oxidation kinetics in the presence of water over Au/TiO2 and Au/Al2O3 catalysts, reaching the following mechanistic conclusions: (i) O2 activation follows a similar mechanism to that proposed in CO oxidation catalysis; (ii) weakly adsorbed H2O is a strong reaction inhibitor; (iii) fast H2 activation occurs at the MSI, and (iv) H2 activation kinetics are inconsistent with traditional dissociative H2 chemisorption on metals. Density …


Characterization And Effect Of Metal Ions On The Formation Of The Thermus Thermophilus Sco Mixed Disulfide Intermediate, Liezelle C. Lopez, Nikita Mukhitov, Lindsey D. Handley, Cristina S. Hamme, Cristina R. Hofman, Lindsay Euers, Jennifer R. Mckinney, Amani D. Piers, Ellen Wadler, Laura M. Hunsicker-Wang Nov 2018

Characterization And Effect Of Metal Ions On The Formation Of The Thermus Thermophilus Sco Mixed Disulfide Intermediate, Liezelle C. Lopez, Nikita Mukhitov, Lindsey D. Handley, Cristina S. Hamme, Cristina R. Hofman, Lindsay Euers, Jennifer R. Mckinney, Amani D. Piers, Ellen Wadler, Laura M. Hunsicker-Wang

Chemistry Faculty Research

The Sco protein from Thermus thermophilus has previously been shown to perform a disulfide bond reduction in the CuA protein from T. thermophilus, which is a soluble protein engineered from subunit II of cytochrome ba 3 oxidase that lacks the transmembrane helix. The native cysteines on TtSco and TtCuA were mutated to serine residues to probe the reactivities of the individual cysteines. Conjugation of TNB to the remaining cysteine in TtCuA and subsequent release upon incubation with the complementary TtSco protein demonstrated the formation of the mixed disulfide intermediate. The cysteine of …


Molecular Recognition Of Methionine-Terminated Peptides By Cucurbit[8]Uril, Zoheb Hirani, Hailey F. Taylor, E. F. Babcock, Andrew T. Bockus, C. D. Varnado Jr., Christopher W. Bielawski, Adam R. Urbach Sep 2018

Molecular Recognition Of Methionine-Terminated Peptides By Cucurbit[8]Uril, Zoheb Hirani, Hailey F. Taylor, E. F. Babcock, Andrew T. Bockus, C. D. Varnado Jr., Christopher W. Bielawski, Adam R. Urbach

Chemistry Faculty Research

This Article describes the molecular recognition of peptides containing an N-terminal methionine (Met) by the synthetic receptor cucurbit[8]-uril (Q8) in aqueous solution and with submicromolar affinity. Prior work established that Q8 binds with high affinity to peptides containing aromatic amino acids, either by simultaneous binding of two aromatic residues, one from each of two different peptides, or by simultaneous binding of an aromatic residue and its immediate neighbor on the same peptide. The additional binding interface of two neighboring residues suggested the possibility of targeting nonaromatic peptides, which have thus far bound only weakly to synthetic receptors. A peptide library …


Functional And Biochemical Characterization Of Dib1'S Role In Pre-Messenger Rna Splicing, Christian C. Schreib, Emily K. Bowman, Cody A. Hernandez, Amber L. Lucas, Camile H. S. Potts, Corina Maeder May 2018

Functional And Biochemical Characterization Of Dib1'S Role In Pre-Messenger Rna Splicing, Christian C. Schreib, Emily K. Bowman, Cody A. Hernandez, Amber L. Lucas, Camile H. S. Potts, Corina Maeder

Chemistry Faculty Research

The spliceosome is a dynamic macromolecular machine that undergoes a series of conformational rearrangements as it transitions between the several states required for accurate splicing. The transition from the B to Bact is a key part of spliceosome assembly and is defined by the departure of several proteins, including essential U5 component Dib1. Recent structural studies suggest that Dib1 has a role in preventing premature spliceosome activation, as it is positioned adjacent to the U6 snRNA ACAGAGA and the U5 loop I, but its mechanism is unknown. Our data indicate that Dib1 is a robust protein that tolerates incorporation of …


Factors Affecting The Association Of Single- And Double-Stranded Rnas With Montmorillonite Nanoclays, A. Gujjari, B. V. Rodriguez, J. Pescador, Corina Maeder, G. W. Beall, L. K. Lewis Apr 2018

Factors Affecting The Association Of Single- And Double-Stranded Rnas With Montmorillonite Nanoclays, A. Gujjari, B. V. Rodriguez, J. Pescador, Corina Maeder, G. W. Beall, L. K. Lewis

Chemistry Faculty Research

Montmorillonite (MMT) nanoclays exist as single and stacked sheet-like structures with large surface areas that can form stable associations with many naturally occurring biomolecules, including nucleic acids. They have been utilized successfully as vehicles for delivery of both drugs and genes into cells. Most previous studies have focused on interactions of MMT with DNA. In the current study, we have investigated the binding of small RNAs similar to those used for RNA interference (RNAi) therapy to two major forms of the clay, Na-MMT and Ca-MMT. Association of both forms of MMT with several double-stranded RNAs (dsRNAs), including 25mers, 54mers and …


Evaluating Differences In The Active-Site Electronics Of Supported Au Nanoparticle Catalysts Using Hammett And Dft Studies, G. Kumar, Luke Tibbitts, Jaclyn Newell, Basu Panthi, Ahana Mukhopadhyay, Robert M. Rioux, Christopher J. Pursell, M. Janik, Bert D. Chandler Mar 2018

Evaluating Differences In The Active-Site Electronics Of Supported Au Nanoparticle Catalysts Using Hammett And Dft Studies, G. Kumar, Luke Tibbitts, Jaclyn Newell, Basu Panthi, Ahana Mukhopadhyay, Robert M. Rioux, Christopher J. Pursell, M. Janik, Bert D. Chandler

Chemistry Faculty Research

Supported metal catalysts, which are composed of metal nanoparticles dispersed on metal oxides or other high-surface-area materials, are ubiquitous in industrially catalysed reactions. Identifying and characterizing the catalytic active sites on these materials still remains a substantial challenge, even though it is required to guide rational design of practical heterogeneous catalysts. Metal-support interactions have an enormous impact on the chemistry of the catalytic active site and can determine the optimum support for a reaction; however, few direct probes of these interactions are available. Here we show how benzyl alcohol oxidation Hammett studies can be used to characterize differences in the …


Chalcogen Impact On Covalency Within Molecular [Cu33-E)]3+ Clusters (E = O, S, Se): A Synthetic, Spectroscopic, And Computational Study, B. J. Cook, G. N. Di Francesco, R. B. Ferreira, J. T. Lukens, K. E. Silberstein, B. C. Keegan, V. J. Catalano, K. M. Lancaster, Jason M. Shearer, L. J. Murray Jan 2018

Chalcogen Impact On Covalency Within Molecular [Cu3(Μ3-E)]3+ Clusters (E = O, S, Se): A Synthetic, Spectroscopic, And Computational Study, B. J. Cook, G. N. Di Francesco, R. B. Ferreira, J. T. Lukens, K. E. Silberstein, B. C. Keegan, V. J. Catalano, K. M. Lancaster, Jason M. Shearer, L. J. Murray

Chemistry Faculty Research

Reaction of the tricopper(I)-dinitrogen tris(β-diketiminate) cyclophane, Cu3(N2)L, with O-atom-transfer reagents or elemental Se affords the oxido-bridged tricopper complex Cu33-O)L (2) or the corresponding Cu33-Se)L (4), respectively. For 2 and 4, incorporation of the bridging chalcogen donor was supported by electrospray ionization mass spectrometry and K-edge X-ray absorption spectroscopy (XAS) data. Cu L2,3-edge X-ray absorption data quantify 49.5% Cu 3d character in the lowest unoccupied molecular orbital of 2, with Cu 3d participation decreasing to 33.0% in 4 and 40.8% in the related sulfide cluster Cu3 …