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Articles 1 - 15 of 15
Full-Text Articles in Physical Sciences and Mathematics
Toxicant Formation In Dabbing: The Terpene Story, Jiries Meehan-Attrash, Wentai Luo, Robert M. Strongin
Toxicant Formation In Dabbing: The Terpene Story, Jiries Meehan-Attrash, Wentai Luo, Robert M. Strongin
Chemistry Faculty Publications and Presentations
Inhalable, noncombustible cannabis products are playing a central role in the expansion of the medical and recreational use of cannabis. In particular, the practice of “dabbing” with butane hash oil has emerged with great popularity in states that have legalized cannabis. Despite their growing popularity, the degradation product profiles of these new products have not been extensively investigated. The study herein focuses on the chemistry of myrcene and other common terpenes found in cannabis extracts. Methacrolein, benzene, and several other products of concern to human health were formed under the conditions that simulated realworld dabbing. The terpene degradation products observed …
Lyapunov Exponents And The Belousov-Zhabotinsky Oscillator: An Interactive Computational Approach, Matthew W. Eskew, Reuben H. Simoyi
Lyapunov Exponents And The Belousov-Zhabotinsky Oscillator: An Interactive Computational Approach, Matthew W. Eskew, Reuben H. Simoyi
Chemistry Faculty Publications and Presentations
The Belousov-Zhabotinsky (BZ) chemical oscillator is the most studied oscillator. It has been modelled on the basis of single-step mechanisms which have been continuously refined since the seminal manuscript by Field, Koros and Noyes in 1972. This manuscript reports on a unique way of modelling the global dynamics of the oscillator by assuming that the BZ oscillator has shown chaotic behaviour. The unique mathematical definition of chaos is very stringent, and, in this manuscript, we attempt to trace this unique exotic behaviour by the use of ‘onto’ maps of the interval onto itself which are known to exhaustively show a …
Formaldehyde Hemiacetal Sampling, Recovery, And Quantification From Electronic Cigarette Aerosols, James C. Salamanca, Ian Munhenzva, Jorge O. Escodedo, R. Paul Jensen, Angela Shaw, Robert Campbell, Wentai Luo, David H. Peyton, Robert Strongin
Formaldehyde Hemiacetal Sampling, Recovery, And Quantification From Electronic Cigarette Aerosols, James C. Salamanca, Ian Munhenzva, Jorge O. Escodedo, R. Paul Jensen, Angela Shaw, Robert Campbell, Wentai Luo, David H. Peyton, Robert Strongin
Chemistry Faculty Publications and Presentations
The electronic cigarette solvents propylene glycol and glycerol are known to produce toxic byproducts such as formaldehyde, acetaldehyde and acrolein. However, the aerosol toxin yield depends upon a variety of chemical and physical variables. The formaldehyde hemiacetals derived from these solvents were reported as major electronic cigarette aerosol components by us in 2015. In the study described herein, the formaldehyde hemiacetals were found at higher levels than those of free formaldehyde via an orthogonal sample collection protocol. In addition, the common aldehyde collection methods for electronic cigarettes, such as impingers and sorbent tubes containing DNPH, significantly underestimate the levels of …
Life’S Late Digital Revolution And Why It Matters For The Study Of The Origins Of Life, David A. Baum, Niles Lehman
Life’S Late Digital Revolution And Why It Matters For The Study Of The Origins Of Life, David A. Baum, Niles Lehman
Chemistry Faculty Publications and Presentations
The information contained in life exists in two forms, analog and digital. Analog information is manifest mainly in the differing concentrations of chemicals that get passed from generation to generation and can vary from cell to cell. Digital information is encoded in linear polymers such as DNA and RNA, whose side chains come in discrete chemical forms. Here, we argue that the analog form of information preceded the digital. Acceptance of this dichotomy, and this progression, can help direct future studies on how life originated and initially complexified on the primordial Earth, as well as expected trajectories for other, independent …
Aryl Transfer Selectivity In Metal-Free Reactions Of Unsymmetrical Diaryliodonium Salts, David Stuart
Aryl Transfer Selectivity In Metal-Free Reactions Of Unsymmetrical Diaryliodonium Salts, David Stuart
Chemistry Faculty Publications and Presentations
Aromatic rings are found in a wide variety of products, including pharmaceuticals, agrochemicals, and functional materials. Diaryliodonium salts are novel reagents used to transfer aryl groups under both metal-free and metal-catalyzed reactions and thereby synthesize arene-containing compounds. This review focuses on recent studies in selective aryl transfer reactions from unsymmetrical diaryliodonium salts under metal-free conditions. Reactions reported from 2008 to 2017, which represents a period of significant growth in diaryliodonium salt chemistry, are presented and organized by the type of reactive intermediate formed in the reaction. Specifically, reactions involving λ3-iodane, λ3-iodane radical anions, aryl radicals, and …
The Camkii Holoenzyme Structure In Activation Competent Conformations, Janette B. Myers, Vincent Zaegel, Steven J. Coultrap, Adam P. Miller, K. Ulrich Bayer, Steve L. Reichow
The Camkii Holoenzyme Structure In Activation Competent Conformations, Janette B. Myers, Vincent Zaegel, Steven J. Coultrap, Adam P. Miller, K. Ulrich Bayer, Steve L. Reichow
Chemistry Faculty Publications and Presentations
The Ca2+/calmodulin-dependent protein kinase II (CaMKII) assembles into large 12-meric holoenzymes, which is thought to enable regulatory processes required for synaptic plasticity underlying learning, memory and cognition. Here we used single particle electron microscopy (EM) to determine a pseudoatomic model of the CaMKIIα holoenzyme in an extended and activation-competent conformation. The holoenzyme is organized by a rigid central hub complex, while positioning of the kinase domains is highly flexible, revealing dynamic holoenzymes ranging from 15–35 nm in diameter. While most kinase domains are ordered independently, ~20% appear to form dimers and
Simplified Reversed Chloroquines To Overcome Malaria Resistance To Quinoline-Based Drugs, Bornface Gunsaru, Steven J. Burgess, Westin Morrill, Jane X. Kelly, Shawheen Shomloo, Martin J. Smilkstein, Katherine May Liebman, David H. Peyton
Simplified Reversed Chloroquines To Overcome Malaria Resistance To Quinoline-Based Drugs, Bornface Gunsaru, Steven J. Burgess, Westin Morrill, Jane X. Kelly, Shawheen Shomloo, Martin J. Smilkstein, Katherine May Liebman, David H. Peyton
Chemistry Faculty Publications and Presentations
Building on our earlier work of attaching a chemosensitizer (reversal agent) to a known drug pharmacophore, we have now expanded the structure-activity relationship study to include simplified versions of the chemosensitizer. The change from two aromatic rings in this head group to a single ring does not appear to detrimentally affect the antimalarial activity of the compounds. Data from in vitro heme binding and beta-hematin inhibition assays suggest that the single aromatic RCQ compounds retain activities against Plasmodium falciparum similar to those of CQ, although other mechanisms of action may be relevant to their activities.
Quef-Like, A Non-Homologous Archaeosine Synthase From The Crenarchaeota, Adriana Bon Ramos, Lide Bao, Ben Turner, Valérie De Crécy-Lagard, Dirk Iwata-Reuyl
Quef-Like, A Non-Homologous Archaeosine Synthase From The Crenarchaeota, Adriana Bon Ramos, Lide Bao, Ben Turner, Valérie De Crécy-Lagard, Dirk Iwata-Reuyl
Chemistry Faculty Publications and Presentations
Archaeosine (G+) is a structurally complex modified nucleoside ubiquitous to the Archaea, where it is found in the D-loop of virtually all archaeal transfer RNA (tRNA). Its unique structure, which includes a formamidine group that carries a formal positive charge, and location in the tRNA, led to the proposal that it serves a key role in stabilizing tRNA structure. Although G+ is limited to the Archaea, it is structurally related to the bacterial modified nucleoside queuosine, and the two share homologous enzymes for the early steps of their biosynthesis. In the Euryarchaeota, the last step of the archaeosine biosynthetic pathway …
Topological And Thermodynamic Factors That Influence The Evolution Of Small Networks Of Catalytic Rna Species, Jessica Anne Mellor Yeates, Philippe Nghe, Niles Lehman
Topological And Thermodynamic Factors That Influence The Evolution Of Small Networks Of Catalytic Rna Species, Jessica Anne Mellor Yeates, Philippe Nghe, Niles Lehman
Chemistry Faculty Publications and Presentations
An RNA-directed recombination reaction can result in a network of interacting RNA species. It is now becoming increasingly apparent that such networks could have been an important feature of the RNA world during the nascent evolution of life on the Earth. However, the means by which such small RNA networks assimilate other available genotypes in the environment to grow and evolve into the more complex networks that are thought to have existed in the prebiotic milieu are not known. Here, we used the ability of fragments of the Azoarcus group I intron ribozyme to covalently self-assemble via genotype-selfish and genotype-cooperative …
Mechanism And Catalytic Strategy Of The Prokaryotic Specific Gtp Cyclohydrolase Ib, Naduni Paranagama, Shilah A. Bonnett, Jonathan Alvarez, Amit Luthra, Boguslaw Stec, Andrew Gustafson, Dirk Iwata-Reuyl, Manal A. Swairjo
Mechanism And Catalytic Strategy Of The Prokaryotic Specific Gtp Cyclohydrolase Ib, Naduni Paranagama, Shilah A. Bonnett, Jonathan Alvarez, Amit Luthra, Boguslaw Stec, Andrew Gustafson, Dirk Iwata-Reuyl, Manal A. Swairjo
Chemistry Faculty Publications and Presentations
GTP cyclohydrolase I catalyzes the first step in folic acid biosynthesis in bacteria and plants, biopterin biosynthesis in mammals, and the biosynthesis of 7-deazaguanosine modified tRNA nucleosides in bacteria and archaea. The type IB GTP cyclohydrolase (GCYH-IB) is a prokaryotic-specific enzyme found in a number of pathogens. GCYH-IB is structurally distinct from the canonical type IA GTP cyclohydrolase involved in biopterin biosynthesis in humans and animals, and thus is of interest as a potential antibacterial drug target. We report kinetic and inhibition data of Neisseria gonorrhoeae GCYH-IB, and two high-resolution crystal structures of the enzyme; one in complex with the …
Benzene Formation In Electronic Cigarettes, James F. Pankow, Kilsun Kim, Kevin J. Mcwhirter, Wentai Luo, Jorge O. Escobedo, Robert M. Strongin, Anna K. Duell, David H. Peyton
Benzene Formation In Electronic Cigarettes, James F. Pankow, Kilsun Kim, Kevin J. Mcwhirter, Wentai Luo, Jorge O. Escobedo, Robert M. Strongin, Anna K. Duell, David H. Peyton
Chemistry Faculty Publications and Presentations
The heating of the fluids used in electronic cigarettes (“e-cigarettes”) used to create “vaping” aerosols is capable of causing a wide range of degradation reaction products. We investigated formation of benzene (an important human carcinogen) from e-cigarette fluids containing propylene glycol (PG), glycerol (GL), benzoic acid, the flavor chemical benzaldehyde, and nicotine.
Protection Of The Queuosine Biosynthesis Enzyme Quef From Irreversible Oxidation By A Conserved Intramolecular Disulfide, Adeba Mohammad, Adriana Bon Ramos, Bobby W.K. Lee, Spencer William Cohen, Maryam K. Kiani, Dirk Iwata-Reuyl, Boguslaw Stec, Manal A. Swairjo
Protection Of The Queuosine Biosynthesis Enzyme Quef From Irreversible Oxidation By A Conserved Intramolecular Disulfide, Adeba Mohammad, Adriana Bon Ramos, Bobby W.K. Lee, Spencer William Cohen, Maryam K. Kiani, Dirk Iwata-Reuyl, Boguslaw Stec, Manal A. Swairjo
Chemistry Faculty Publications and Presentations
QueF enzymes catalyze the nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reduction of the nitrile group of 7-cyano-7-deazaguanine (preQ0) to 7-aminomethyl-7-deazaguanine (preQ1) in the biosynthetic pathway to the tRNA modified nucleoside queuosine. The QueF-catalyzed reaction includes formation of a covalent thioimide intermediate with a conserved active site cysteine that is prone to oxidation in vivo. Here, we report the crystal structure of a mutant of Bacillus subtilis QueF, which reveals an unanticipated intramolecular disulfide formed between the catalytic Cys55 and a conserved Cys99 located near the active site. This structure is more symmetric than the substrate-bound structure and exhibits major rearrangement of …
Solvent Chemistry In The Electronic Cigarette Reaction Vessel, Robert Paul Jensen, Robert M. Strongin, David H. Peyton
Solvent Chemistry In The Electronic Cigarette Reaction Vessel, Robert Paul Jensen, Robert M. Strongin, David H. Peyton
Chemistry Faculty Publications and Presentations
Knowledge of the mechanism of formation, levels and toxicological profiles of the chemical products in the aerosols (i.e., vapor plus particulate phases) of e-cigarettes is needed in order to better inform basic research as well as the general public, regulators, and industry. To date, studies of e-cigarette emissions have mainly focused on chromatographic techniques for quantifying and comparing the levels of selected e-cigarette aerosol components to those found in traditional cigarettes. E-cigarettes heat and aerosolize the solvents propylene glycol (PG) and glycerol (GLY), thereby affording unique product profiles as compared to traditional cigarettes. The chemical literature strongly suggests that there …
Far-Red And Near-Infrared Seminaphthofluorophores For Targeted Pancreatic Cancer Imaging, Lei Wang, Connor W. Barth, Martha Sibrian-Vazquez, Jorge O. Escodedo, Mark Lowry, John Muschler, Haiyan Li, Summer L. Gibbs, Robert Strongin
Far-Red And Near-Infrared Seminaphthofluorophores For Targeted Pancreatic Cancer Imaging, Lei Wang, Connor W. Barth, Martha Sibrian-Vazquez, Jorge O. Escodedo, Mark Lowry, John Muschler, Haiyan Li, Summer L. Gibbs, Robert Strongin
Chemistry Faculty Publications and Presentations
Molecular probes that selectively highlight pancreatic cancer (PC) tissue have the potential to improve pancreatic ductal adenocarcinoma (PDAC) margin assessment through the selective highlighting of individual PC cells. Herein, we report a simple and unique family of systematically modified red and near-infrared fluorescent probes that exhibit a field-effect-derived redshift. Two of thirteen probes distributed to the normal mouse pancreas following systemic administration. One selectively accumulated in genetically modified mouse models of PDAC. The probe exhibited intracellular accumulation and enabled visualization of four levels of the structure, including the whole organ, resected tissue, individual cells, and subcellular organelles. In contrast to …
The T6a Modification Acts As A Positive Determinant For The Anticodon Nuclease Prrc, And Is Distinctively Nonessential In Streptococcus Mutans, Jo Marie Bacusmo, Silvia S. Orsini, Jennifer Hu, Michael Demott, Patrick C. Thiaville, Ameer Elfarash, Mellie June Paulines, Diego Rojas-Benítez, Birthe Meineke, Christopher Deutsch, Dirk Iwata-Reuyl, Patrick A. Limbach, Peter C. Dedon, Kelly C. Rice, Stewart Shuman, Valérie De Crécy-Lagard
The T6a Modification Acts As A Positive Determinant For The Anticodon Nuclease Prrc, And Is Distinctively Nonessential In Streptococcus Mutans, Jo Marie Bacusmo, Silvia S. Orsini, Jennifer Hu, Michael Demott, Patrick C. Thiaville, Ameer Elfarash, Mellie June Paulines, Diego Rojas-Benítez, Birthe Meineke, Christopher Deutsch, Dirk Iwata-Reuyl, Patrick A. Limbach, Peter C. Dedon, Kelly C. Rice, Stewart Shuman, Valérie De Crécy-Lagard
Chemistry Faculty Publications and Presentations
Endoribonuclease toxins (ribotoxins) are produced by bacteria and fungi to respond to stress, eliminate non-self competitor species, or interdict virus infection. PrrC is a bacterial ribotoxin that targets and cleaves tRNALys UUU in the anticodon loop. In vitro studies suggested that the post-transcriptional modification threonylcarbamoyl adenosine (t6A) is required for PrrC activity but this prediction had never been validated in vivo. Here, by using t6A-deficient yeast derivatives, it is shown that t6A is a positive determinant for PrrC proteins from various bacterial species. Streptococcus mutans is one of the few bacteria where the t …