1. Spectrophotometric Analysis of Cardiac Glycosides in Milkweed, Erin LeVoir (Chemistry, Biology), Joshua Waschak (Chemistry), Shane Rowan (Chemistry), Clay Garris (Chemistry), Michael Everest, Chemistry
Cardiac glycosides are naturally occurring compounds found in various plants and insects. These compounds are characterized by their toxicity as well as their medicinal properties. Asclepias, commonly known as Milkweed, is a plant containing cardiac glycosides that is traditionally part of the diet of the Myaamia Native American tribe. In order to determine the degree of toxicity of milkweed as grown and prepared by the Myaamia people, we are photometrically determining the amount cardiac glycosides in Asclepias. 2,2,4,4-tetranitrodriphenyl (TNDP) selectively turns blue in the presence of cardiac glycosides, and was used in samples of plant extract. Spectrophotometric analysis measured the concentration of digitoxin in a mature plant. We found that the average amount of digitoxin in the plants was 0.8±0.3 grams of glycoside per kilogram of the plant. Future work involves calculating cardiac glycoside concentration over the full growth period of the plant.
2. Formation of b-sheet fibrils from octapeptide mixtures, Benjamin Trapp (Chemistry, Biology), Tjitske Veldstra '14, Dean LaBarba '13, Kristi Lazar Cantrell, Chemistry
The association of â-sheets has been implicated in the formation of protein aggregates and fibrils observed in many human diseases, including Alzheimer’s disease and Huntington’s disease. The following octapeptides were synthesized by manual solid phase peptide synthesis to investigate whether engineering electrostatic and hydrophobic interactions in the peptides induces â-sheet amyloid fibril formation: (1) Ac-EFFKFFEYNH2, (2) Ac-KFFEFFKY-NH2, (3) Ac-KFFKFFKY-NH2, and (4) Ac-EFFEFFEY-NH2. The peptides were purified using High Pressure Liquid Chromatography (HPLC) and the masses were confirmed using mass spectrometry. The propensity of Peptides 1-4 to form fibrils was investigated by incubating the individual peptides and peptide mixtures. Fibril formation was tested by Thioflavin T fluorescence, circular dichroism and electron microscopy.
3. EW-CRDS and the Spatial Investigation of Adsorption on a Fused Glass Prism, Christopher Kenji Sue (Chemistry, Biology), Jordan Kohl (Chemistry), Nick Sovronec (Chemistry), Michael Everest, Chemistry
Phosphotungstic acid (PW12O40) has been shown to improve the rate of proton transfer in polymer electrolyte membrane fuel cells. The interactions between (3-aminopropyl)- trimethoxysilane (APTMS) and phosphotungstic acid (PTA) were studied on a fusedsilica prism through the use of evanescent-wave cavity-ringdown spectroscopy (EWCRDS). It was discovered that PTA will adsorb irreversibly to higher concentrations of APTMS. The adsorption of PTA to APTMS showed a ΔG° of adsorption of -81 kJ/mole, indicating PTA adsorption to APTMS is favorable under standard state conditions.
4. Effect of Enhanced Adlayer Ordering by 1-Chloroalkanes on a Mixture of Naphthalene and 2-Ethylnaphthalene on Al2O3, Rachel DeHoog (Chemistry), Alice Geng (Chemistry), Melissa Shew (Chemical Engineering), Allan Nishimura, Chemistry
Bilayers of 1-chloroalkane (1-CA) and a 5:1 mixture of naphthalene (N) and 2-ethylnaphthalene (2-EN) were formed by vapor deposition onto a single crystal of Al2O3. The fluorescence was monitored as the surface temperature of the Al2O3 was linearly ramped in a temperature programmed desorption (TPD) experiment. During the TPD, 1-CA caused the adlayer containing the mixture to undergo much more enhanced irreversible structural relaxation.
5. Effect of Naphthalene on the Desorption of 1-Chloroalkanes on α-Alumina, Alice Geng (Chemistry), Rachel DeHoog (Chemistry), Trevor Ban (Chemistry), Andrew Olson (Chemistry), Allan Nishimura, Chemistry
When an adsorbate, such as naphthalene, that has a relatively high desorption temperature is placed above another such as chloroalkane that desorbs at a lower temperature, the desorption temperature of the chloroalkane is raised. In order to understand the cause, a systematic study was done on the desorption of a homologous series of chloroalkanes.
6. Structural properties of Phenanthroline and Related Groups, Christopher Wong (Chemistry), Steve Contakes, Chemistry
The purpose of this project was to assign nuclear magnetic resonance (NMR) spectra for the characterization of metal diimine complexes and to determine the ligand peak shifts resulting from the formation of these complexes. Initial work on this subject revolved around the development of an improved synthesis pathway for the Ruthenium diimine complex and characterization of the complex by means of NMR, UV spectroscopy, and Cyclic Voltammetry. This current stage of the project was focused on the assignment of proton and carbon resonances for a number of 2,2’-bipyridine and 1,10-phenanthroline groups using an array of 1H, 13C, COSY, and HSQC NMR experiments.
7. Synthesis and Structural Characterization of Mn(II)Salen and a Mn(II)Salen-(N-ferrocenyl isonicotinamide) Adduct, Jaagruthi Chitithoti (Chemistry, Cellular & Molecular Biology), Steve Contakes, Chemistry
A Mn(II)Salen and Mn(II)Salen-N-ferrocenyl isonicotinamide were synthesized and structurally characterized. ESI-MS spectra showed that the Mn(II)Salen compound was formed in its synthesis. NMR spectra proved not to be effective in characterizing the compound due to its paramagnetic properties. The Mn(II)Salen product was then reacted with N-ferrocenyl isonicotinamide, to mimic the redox-active axial ligand in the CP450 human liver enzyme cytochrome. The Mn(II)Salen-N-ferrocenyl isonicotinamide is currently being structurally characterized. ESI-MS spectra shows a small presence of the adduct being formed. Again, NMR spectra is not effective in characterizing the adduct due to its paramagnetic properties. The Mn(II)Salen complex will continue to be analyzed using UV-Vis Spectroscopy, IR Spectroscopy, and Crystallography.
8. The Role of Tau Protein Oligomerization in Neurodegenerative Disease, Nicolette Dressler (Chemistry, Biology), Megan Korff (Chemistry), Kristi Lazar Cantrell, Chemistry
Tau protein is an essential microtubule-associated protein that provides support to the nervous system. In some cases, the natively unfolded tau forms abnormal fibrillary deposits in the brain and causes neurodegenerative disease. Recent research suggests that oligomers of tau may be more toxic than fibrils. A 39-mer fragment was chosen to investigate the oligomerization potential in a region of tau. The peptide was synthesized by solid phase peptide synthesis. Mass spectral data revealed a significant amount of oxidized product. The reduction and purification of the peptide will be discussed. The purified peptide has been studied using electron microscopy and circular dichroism.