Biochemistry, Biophysics, and Structural Biology Commons^™

Microsolvation Of Anions By Molecules Forming Ch∙∙X- Hydrogen Bonds, Steve Scheiner, Binod Nepal

Chemistry and Biochemistry Faculty Publications

Various anions were surrounded by n molecules of CF₃H, which was used as a prototype CH donor solvent, and the structures and energies studied by M06-2X calculations with a 6-31+G∗∗ basis set. Anions considered included the halides F^-, Cl^-, Br^- and I^-, as well as those with multiple proton acceptor sites: CN^-, NO₃ ^-, HCOO^-, CH₃COO^-, HSO₄ ^-, H₂PO₄ ^-, and anions with higher charges SO₄ ^2-, HPO₄ ^2- and PO_{4 …}

Cobalt-Centred Boron Molecular Drums With The Highest Coordination Number In The Cob16− Cluster, Ivan A. Popov, Tian Jian, Gary V. Lopez, Alexander I. Boldyrev, Lai-Sheng Wang

Chemistry and Biochemistry Faculty Publications

The electron deficiency and strong bonding capacity of boron have led to a vast variety of molecular structures in chemistry and materials science. Here we report the observation of highly symmetric cobalt-centered boron drum-like structures of CoB16⁻, characterized by photoelectron spectroscopy and ab initio calculations. The photoelectron spectra display a relatively simple spectral pattern, suggesting a high symmetry structure. Two nearly degenerate isomers with D8d(I) and C4v (II) symmetries are found computationally to compete for the global minimum. These drum-like structures consist of two B8 rings sandwiching a cobalt atom, which has the highest …

Microbial-Derived Oils And Value-Added Products: Biosynthesis And Applications For Biofuel Production, Alex T. Mccurdy

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Efforts are being made to replace petroleum-derived fuels with biofuels in a cost competitive manner. It is apparent that the continued use of petroleum is futile as population and technological growth put increasing pressure on the demand for cheap energy and chemicals. Diminishing resources, civil unrest in the Middle East, and the impact of using petrochemicals on the environment are critical driving forces for research in generating renewable petroleum replacements that can be produced with a limited carbon-footprint. Today, biofuels are derived mostly from land-based plants, but their potential for displacing petroleum is limited due to the competition with available …

Dna Methylation In Lung Tissues Of Mouse Offspring Exposed In Utero To Polycyclic Aromatic Hydrocarbons, Trevor J. Fish

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Polycyclic aromatic hydrocarbons (PAHs) comprise an important class of environmental pollutants that are known to cause lung cancer in animals and suspected lung carcinogens in humans. PAHs are also known to cause cancer in offspring when provided to a pregnant mouse. Some evidence from cell-based studies points to PAHs as modulators of the epigenome, that is modifications to DNA structure that control the expression of genes. Inappropriate changes to the epigenome and consequently expression of cancer-critical genes are often characteristic of cancer cells. The objective of this thesis research was to determine the impact of transplacental exposure to two model …

Binding Interactions Of (R)- And (S)-Hydroxypropyl-Com Dehydrogenases And The Zinc Knuckle Proteins Air1 And Air2, Jeremy W. Bakelar

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A thorough understanding of protein function requires knowledge of how proteins interact with their substrates and with other proteins. The work entailed in this dissertation describes the binding interactions of proteins from two different model systems: (1) the dehydrogenase enzymes R- and S-HPCDH and (2) the zinc knuckle proteins Air1 and Air2.

R- and S-HPCDH are highly similar enzymes (42% identical) that function in a unique metabolic pathway found in the soil bacterium Xanthobacter autotrophicus. The bacterium produces R- and S-HPCDH simultaneously to facilitate the transformation of two different forms of the organic …

Development Of Genetic Goat And Hamster Models Of Atrial Fibrillation And Long Qt Syndrome; And Genetic Hamster Models Of Middle East Respiratory Syndrome, Dane A. Rasmussen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Atrial fibrillation (AF) and long QT syndrome (LQTS) are potentially lethal heart rhythm disorders that can be caused by mutations in the potassium channel gene KCNQ1. Middle East Respiratory Syndrome (MERS) is a viral infection with the potential to replicate the devastating effects of the SARS outbreak in 2003. All three of these diseases are in need of genetic animal models.

To address these needs, my thesis project focused on the development of genetic goat and hamster models of AF and LQTS, and genetic hamster models of MERS. Because of the goat’s similar organ size/physiology and the hamster’s similar lipid …

The Infrared Spectrum Of The He-C2d2 Complex, N. Moazzen-Ahmadi, A. R. W. Mckellar, Berta Fernandez, David Farrelly

Chemistry and Biochemistry Faculty Publications

Spectra of the helium-acetylene complex are elusive because this weakly bound system lies close to the free rotor limit. Previously, limited assignments of He–C2D2 transitions in the R(0) region of the ν3 fundamental band (≈2440 cm⁻¹) were published. Here, new He–C2D2 infrared spectra of this band are obtained using a tunable optical parametric oscillator laser source to probe a pulsed supersonic slit jet expansion from a cooled nozzle, and the analysis is extended to the weaker and more difficult P(1) and R(1) regions. A term value approach is used to obtain a consistent set of “experimental” energy levels. …

Metabolome Searcher: A High Throughput Tool For Metabolite Identification And Metabolic Pathway Mapping Directly From Mass Spectrometry And Using Genome Restriction, A. Ranjitha Dhanasekaran, Jon L. Pearson, Balasubramanian Ganesan, Bart C. Weimer

Nutrition, Dietetics, and Food Sciences Faculty Publications

Background

Mass spectrometric analysis of microbial metabolism provides a long list of possible compounds. Restricting the identification of the possible compounds to those produced by the specific organism would benefit the identification process. Currently, identification of mass spectrometry (MS) data is commonly done using empirically derived compound databases. Unfortunately, most databases contain relatively few compounds, leaving long lists of unidentified molecules. Incorporating genome-encoded metabolism enables MS output identification that may not be included in databases. Using an organism’s genome as a database restricts metabolite identification to only those compounds that the organism can produce.

Results

To address the challenge of …

Intramolecular S···O Chalcogen Bond As Stabilizing Factor In Geometry Of Substituted Phenyl-Sf3 Molecules, Vincent De Paul Nziko, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Density functional methods are used to examine the geometries and energetics of molecules containing a phenyl ring joined to the trigonal bipyramidal SF3 framework. The phenyl ring has a strong preference for an equatorial position. This preference remains when one or two ether -CH2OCH3 groups are added to the phenyl ring, ortho to SF3, wherein an apical structure lies nearly 30 kcal/mol higher in energy. Whether equatorial or apical, the molecule is stabilized by a S···O chalcogen bond, sometimes augmented by CH···F or CH···O H-bonds. The strength of the intramolecular S···O bond is estimated to lie in the range between …

Protein Motions Control Activity In Biologically Important Phosphatases, Ryan Hirschi, Gwen Moise

Research on Capitol Hill

No abstract provided.

Synthesis And Characterization Of Polymer (Sulfonated Poly-Ether-Ether-Ketone) Based Nanocomposite (H-Boron Nitride) Membrane For Hydrogen Storage, Naresh Muthu, S. Rajashabala, R. Kannan

Chemistry and Biochemistry Faculty Publications

The development of light weight and compact hydrogen storage materials is still prerequisite to fuel-cell technology to be fully competitive. The present experimental study reports the hydrogen storage capability of sulfonated poly-ether-ether-ketone (SPEEK)-hexagonal boron nitride (h-BN) (SPEEK-h-BN) nanocomposite membranes. The nanocomposite membranes are prepared by considering various amount of h-BN (0, 1, 3 and 5 wt. %) by phase inversion technique. The degree of sulfonation of the PEEK (SPEEK) is found to be 65% by Proton Nuclear Magnetic Resonance (¹H NMR) spectroscopy. Hydrogen adsorption studies have been carried out using a Seiverts-like hydrogenation setup. The membranes are characterized …

Antifungal Amphiphilic Aminoglycoside K20: Bioactivities And Mechanism Of Action, Sanjib K. Shrestha, Cheng-Wei Tom Chang, Nicole Meissner, John Oblad, Jaya P. Shrestha, Kevin N. Sorensen, Michelle M. Grilley, Jon Y. Takemoto

Chemistry and Biochemistry Faculty Publications

K20 is a novel amphiphilic antifungal aminoglycoside that is synthetically derived from the antibiotic kanamycin A. Reported here are investigations of K20′s antimicrobial activities, cytotoxicity, and fungicidal mechanism of action. In vitro growth inhibitory activities against a variety of human and plant pathogenic yeasts, filamentous fungi, and bacteria were determined using microbroth dilution assays and time-kill curve analyses, and hemolytic and animal cell cytotoxic activities were determined. Effects on Cryptococcus neoformans H-99 infectivity were determined with a preventive murine lung infection model. The antifungal mechanism of action was studied using intact fungal cells, yeast lipid mutants, and small unilamellar lipid …

Cloning And Expression For The Future Characterization Of The Air2 Protein, Emily Sue Frampton

Undergraduate Honors Capstone Projects

Air2 is a eukaryotic protein involved in multiple biological processes including protein-protein interactions as well as RNA binding. Air2 plays a critical role in RNA quality control and also helps regulate post-translational modification of various proteins. Although previous studies have revealed information regarding Air2's roles within a cell, the molecular and structural basis for Air2 function is unclear. Using a codon-optimized version of the Air2 gene, various constructs were created that improved the expression and solubility of Air2. Additionally a co-expression complex of Air2 with a PRMTI mutant, K13S, was made to obtain the Air2 protein with a native binding …

Electron Transfer And Substrate Reduction In Nitrogenase, Karamatullah Danyal

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The reduction of nitrogen to ammonia by the industrial Haber-Bosch process is considered one of the major scientific breakthroughs of the last century. It is considered to be responsible for approximately one third of the world's current population. This growth over the past 50 or so years accompanied by the changes in dietary habits due to economic growth have markedly increased the demand for fixed nitrogen in the form of fertilizer. The Haber-Bosch process and biological nitrogen fixation has been able to fulfil this demand. However, this industrial process is costly due to its high temperature and pressure requirements. Every …

Quantum Mechanical Study Of Weak Molecular Interactions, Upendra Adhikari

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Molecular interactions play key role in the existence of biomolecules like proteins and nucleic acids, and various materials. Molecular interactions are weak forces that hold different molecules or different fragments of the same molecule together, and are often referred to as noncovalent interactions. Due to the complexity in biomolecules, these interactions are still poorly understood. This dissertation presents results from quantum mechanical simulations of various types of noncovalent interactions, which are extremely important for the structure and functions of biomolecules and materials.

A new sort of noncovalent interaction is identified. This new sort of interaction originates from a direct interaction …

Pop2: A Potential Regulator Of Hmt1-Catalyzed Arginine Methylation In Yeast, Celeste Excell

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Protein arginine methylation is an important post-translational modification that is vital in regulating various cellular processes such as gene transcription, cell signaling, and RNA processing. Protein arginine methyltransferases (PRMTs) are responsible for performing this important modification. PRMT1 (protein arginine methyltransferase 1) and Hmt1 (hnRNP methyltransferase 1) are the predominant PRMTs in humans and yeast, respectively. Despite growing momentum in this field, relatively little is understood about PRMT regulation. Further work discovering how PRMTs are regulated will greatly advance our understanding of diseases where PRMTs have been implicated, such as heart disease, viral pathogenesis, and cancer.

It has been discovered that …

Effects Of Charge And Substituent On The S∙∙∙N Chalcogen Bond, U. Adhikari, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Neutral complexes containing a S···N chalcogen bond are compared with similar systems in which a positive charge has been added to the S-containing electron acceptor, using high-level ab initio calculations. The effects on both XS···N and XS+···N bonds are evaluated for a range of different substituents X = CH3, CF3, NH2, NO2, OH, Cl, and F, using NH3 as the common electron donor. The binding energy of XMeS···NH3 varies between 2.3 and 4.3 kcal/mol, with the strongest interaction occurring for X = F. The binding is strengthened by a factor of 2–10 in charged XH2S+···NH3 complexes, reaching a maximum of …

Competition Between Lone Pair-Π, Halogen Bond, And Hydrogen Bond In Adducts Of Water With Perhalogenated Alkenes C2clnf4-N (N = 0-4), U. Adhikari, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

A thorough search of the potential energy surface is carried out for heterodimers of water with C2ClnF4−n. Three different types of interactions are observed. Structures dominated by a lone pair–π interaction have the highest binding energies, and are stabilized by charge transfer from O lone pairs of H2O to the Csingle bondC π* antibonding orbital of the alkene. Halogen-bonded O⋯Cl complexes are slightly less strongly bound, followed by OH⋯X hydrogen bonds. The replacements of Cl by F atoms have only small effects upon binding energies. Inclusion of vibrational and entropic effects removes the clear energetic superiority of lp–π binding energies. …

Complexation Of N So2 Molecules (N=1,2,3) With Formaldehyde And Thioformaldehyde, L. M. Azofra, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Ab initio and density functional theory calculations are used to examine complexes formed between H2CO and H2CS with 1, 2, and 3 molecules of SO2. The nature of the interactions is probed by a variety of means, including electrostatic potentials, natural bond orbital, atoms in molecules, energy decomposition, and electron density redistribution maps. The dimers are relatively strongly bound, with interaction energies exceeding 5 kcal/mol. The structures are cyclic, containing both a O/S⋯S chalcogen bond and a CH⋯O H-bond. Addition of a second SO2 molecule leads to a variety of heterotrimer structures, most of which resemble the original dimer, where …

Complexes Containing Co2 And So2. Mixed Dimers, Trimers And Tetramers, L. M. Azofra, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Mixed dimers, trimers and tetramers composed of SO2 and CO2 molecules are examined by ab initio calculations to identify all minimum energy structures. While AIM formalism leads to the idea of a pair of C···O bonds in the most stable heterodimer, bound by some 2 kcal mol(-1), NBO analysis describes the bonding in terms of charge transfer from O lone pairs of SO2 to the CO π* antibonding orbitals. The second minimum on the surface, just slightly less stable, is described by AIM as containing a single O···O chalcogen bond. The NBO picture is that of two transfers in opposite …

Interaction Between Temozolomide And Water: Preferred Binding Sites, O. E. Kasende, A. Matondo, M. Muzomwe, J. T. Muya, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Computational methods are used to predict the most favorable site of temozolomide towards attack by a water molecule. The energetics of the various complexes are presented as well as their geometries, including perturbations of each subunit caused by the presence of the other. Molecular electrostatic potential and Natural Bond Orbital (NBO) data are used to understand the interactions which conclude the terminal amide group is the preferred attack site where water can act as simultaneous proton donor and acceptor. Other potential proton acceptor N atoms within the aromatic ring structure represent weaker binding sites. Some of the less strongly bound …

Substituent Effects In The Noncovalent Bonding Of So2 To Molecules Containing A Carbonyl Group. The Dominating Role Of The Chalcogen Bond, L. M. Azofra, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The SO2 molecule is paired with a number of carbonyl-containing molecules, and the properties of the resulting complexes are calculated by high-level ab initio theory. The global minimum of each pair is held together primarily by a S···O chalcogen bond wherein the lone pairs of the carbonyl O transfer charge to the π* antibonding SO orbital, supplemented by smaller contributions from weak CH···O H-bonds. The binding energies vary between 4.2 and 8.6 kcal/mol, competitive with even some of the stronger noncovalent forces such as H-bonds and halogen bonds. The geometrical arrangement places the carbonyl O atom above the plane of …

An Exploration Of The Ozone Dimer Potential Energy Surface, L. M. Azofra, I. Alkorta, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The (O3)2 dimer potential energy surface is thoroughly explored at the ab initio CCSD(T) computational level. Five minima are characterized with binding energies between 0.35 and 2.24 kcal/mol. The most stable may be characterized as slipped parallel, with the two O3 monomers situated in parallel planes. Partitioning of the interaction energy points to dispersion and exchange as the prime contributors to the stability, with varying contributions from electrostatic energy, which is repulsive in one case. Atoms in Molecules analysis of the wavefunction presents specific O⋯O bonding interactions, whose number is related to the overall stability of each dimer. All internal …

Strongly Bound Noncovalent (So3)N:H2co Complexes (N = 1, 2), L. M. Azofra, I. Alkorta, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The potential energy surfaces (PES) for the SO3:H2CO and (SO3)2:H2CO complexes were thoroughly examined at the MP2/aug-cc-pVDZ computational level. Heterodimers and trimers are held together primarily by SO chalcogen bonds, supplemented by weaker CHO and/or OC bonds. The nature of the interactions is probed by a variety of means, including electrostatic potentials, AIM, NBO, energy decomposition, and electron density redistribution maps. The most stable dimer is strongly bound, with an interaction energy exceeding 10 kcal mol(-1). Trimers adopt the geometry of the most stable dimer, with an added SO3 molecule situated so as to interact with both of the original …

Investigating The Importance Of The N-Terminal Negative Residues In Human Prmt1, Brooke Siler

Undergraduate Honors Capstone Projects

Many essential physiological pathways, such as cell proliferation, gene expression, and cardiovascular health are regulated by Protein Arginine Methyltransferases (PRMTs) through methylation of arginine residues in protein substrates. Understanding how PRMTs interact with their substrates is pivotal to understanding the biological role of these enzymes, and fundamental to the goal of identifying possible sites to be inhibited through drug therapy. Natural variations in the N-terminus of the PRMTl enzymes and data collected in our lab suggest that the N-terminus is important for activity and/or the binding of protein substrates. Preliminary data collected had led us to hypothesize that the negatively …

Membrane Lipid-Modulated Mechanism Of Action And Non-Cytotoxicity Of Novel Fungicide Aminoglycoside Fg08, Sanjib Shrestha, Michelle Grilley, Marina Y. Fosso, Cheng-Wei Tom Chang, Jon Y. Takemoto

Chemistry and Biochemistry Faculty Publications

A novel aminoglycoside, FG08, that differs from kanamycin B only by a C8 alkyl chain at the 4″-O position, was previously reported. Unlike kanamycin B, FG08 shows broad-spectrum fungicidal but not anti-bacterial activities. To understand its specificity for fungi, the mechanism of action of FG08 was studied using intact cells of the yeast Saccharomyces cerevisiae and small unilamellar membrane vesicles. With exposure to FG08 (30 µg mL−1), 8-fold more cells were stained with fluorescein isothiocyanate, cells had 4 to 6-fold higher K+ efflux rates, and 18-fold more cells were stained with SYTOX Green in comparison to exposure to kanamycin B …

The Phosphoramidase Competency Of Prototypical Phosphatase Catalytic Motifs, Mark P. Haney

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Phosphorylation of proteins is ubiquitous. Phosphorylation can activate proteins, deactivate proteins, assist in signaling, or serve other roles depending upon the biochemical pathway. Attaching phosphate to proteins is accomplished by enzymes called kinases; removing phosphate from proteins is accomplished by enzymes called phosphatases. Cells must regulate their biochemical pathways, and the antipodal roles of kinases and phosphatases represent the yin-yang of phosphorylation.

Phosphorylation of proteins is known to occur on serine, threonine, and tyrosine. This creates a phosphoester bond. Phosphoester bonds have a phosphorus-oxygen (P-O) bond. The ability of phosphatases to cleave such phosphoester bonds is well studied. Phosphorylation of …

Evaluation Of The Tgf-Ss Inhibitor Repsox On The Expression Of Pluripotency Pathways In Murine And Bovine Cells, Davin M. Larsen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Embryonic stem cells are cells which are isolated from early stage embryos and have the theoretical ability to become any adult cell type in the body. In the past few years much research has focused on the use of embryonic stem cells for clinical applications in the treatment of degenerative diseases. Consequently they are a promising tool in the treatment of diseases such as Diabetes and Parkinson’s disease, and could potentially be used in the repair of permanently damaged tissue. However, since these cells are isolated from early stage embryos their successful isolation often results in the destruction of the …

Increased Production And Extraction Efficiency Of Triacylglycerides From Microorganisms And An Enhanced Understanding Of The Pathways Involved In The Production Of Triacylglycerides And Fatty Alcohols, Robert M. Willis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The continued increase in the demand for fossil fuels combined with their ever dwindling supply has prompted the search for a suitable alternative fuel. The research contained within this dissertation seeks to increase the lipid (fat) content of cellular feedstocks, improve extraction efficiencies of lipids, and to understand the pathways involved in the production of fatty alcohols and triacylglycerides, compounds commonly used in many industrial processes, from microbial feedstocks. This work has been done in an attempt to increase the overall economic viability of microbial biofuels production.

The production of biofuels from microalgae used as a feedstock allows for the …

Characterization And Potential Utility Of Porcine Trophoblast-Derived Stem-Like Cells, Edison A. Suasnavas

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In mammalian pregnancy, the placenta is a very important organ which helps to establish a healthy pregnancy. Its functions could be described in four points: 1) It allows the fetus to receive gases and nutrients from the mother in a safe way; 2) it lets the fetus get rid of waste through the mother's kidneys; 3) it releases essential pregnancy-related hormones and growth factors that let the uterus hold the fetus; 4) it secretes immune response regulators to give the fetus immune protection against the mother. Abnormalities in the placenta can be the cause of death to the fetus. Mammalian …