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Section II: Chemistry.

2:00 PHOTODYNAMIC PROPERTIES OF 3,4-DIFLUOROTETRAPHENYL PORPHYRIN **, Adegboye Adeyemo (1), Jonathan Bookout * (2), Benjamin Callahan (2), Donovan Tucker (2) and James LoBue (2), (1) Savannah State University Department of Natural Science and Mathematics, Savannah, GA 31404 and (2) Department of Chemistry Georgia Southern University, Statesboro, GA 30460. The use of electromagnetic radiation to promote chemical reactions can be observed in the variation in the UV-Vis absorption of the target chemical compound. In this experiment, photolysis was carried out on mixtures of diphenylanthracene (DPA) and 3,4-difluorotetraphenylporphyrin (3,4-DFTPP) by exposing the chemical compound to electromagnetic radiation at the wavelengths of 488nm and 670nm. The resulting change in absorption was observed over time and was quantified using Beer's law. Photolysis of these mixtures at 670nm (from a Lasiris 7 mW diode laser for 1 hour) produces very dramatic decrease in absorption of both 3,4-DFTPP and DPA, of 51% and 30% respectively. For photolysis at 488nm (Coherent Innova90 Argon Ion laser at 50 mW for 1 hour) on average the observed decrease in absorption of DFTPP and DPA was 8% and 39% respectively. A discussion of these results will be presented.

2:20 POLYMORPHISM OF 1-METHYLIMIDAZOLIUM 4-NITROPHENOLATE CRYSTALS, Tabitha M. Callaway * and Kenneth L. Martin, Berry College, Mt. Berry, GA 30149. Two different syntheses of 1-methylimidazolium 4-nitrophenolate were carried out by addition of equal moles of l-methylimidazole and 4-nitrophenol (dissolved in acetone for one synthesis, in ethanol for the other). Both syntheses resulted in yellow monoclinic crystals, and Cu-Ka diffraction data sets were collected at 173 K. For a crystalline needle grown from the acetone solution, 9967 X-ray reflections were measured, and a unit cell with a = 7.3273(4) [Angstrom], b = 21.217(1) [Angstrom], c = 11.0567(5) [Angstrom], [beta] = 107.272(4) [degrees], Z = 4, and [P2.sub.1]/a space group was found with R(int) = 0.041. For a crystalline block grown from the ethanol solution, 4954 X-ray reflections were measured, and a unit cell with a = 3.8298(3) [Angstrom], b = 10.1445(7) [Angstrom], c = 21.236(1) [Angstrom], [beta] = 92.525(5) [degrees], Z = 4, and [P2.sub.1] space group was found with R(int) = 0.024. The crystals obtained from acetone solution actually have within the asymmetric unit one 1-methylimidazolium cation and two 4-nitrophenol moieties, which share a disordered hydrogen cation. The proton that was transferred to the 1-methylimidazole is involved in a hydrogen bond to one of the two 4-nitrophenol moieties. The crystals obtained from ethanol solution have within the asymmetric unit one 1-methylimidazolium cation, one 4-nitrophenolate anion, and one 4-nitrophenol molecule.

2:40 EXPRESSION AND PURIFICATION OF OXALATE OXIDASE FROM CERIPORIOPSIS SUBVERMISPORA, Patricia Mousatchie (1) and Ellen W. Moomaw (2), (1) University of Florida, Gainesville, FL 32611 and (2) Gainesville State College, Oakwood, GA 30566. Oxalate oxidase catalyzes the carbon-carbon bond cleavage of oxalate to yield carbon dioxide and hydrogen peroxide. Although there is currently no structural information available for oxalate oxidase from Ceriporiopsis subvermispora (CsOxOx), sequence data and homology modeling indicate that it is the first manganese-containing bicupin enzyme identified that catalyzes this reaction. The best characterized oxalate oxidases are from barley and wheat. These enzymes, also known as germins, contain a single cupin domain and are therefore classified as monocupins. Interestingly, CsOxOx shares greatest sequence homology with the bicupin microbial oxalate decarboxylases. We report here the expression of oxalate oxidase from Ceriporiopsis subvermispora by Pichia pastoris and its subsequent purification. (This project was supported by NSF Grant # MCB-0919908.)

3:00 Break

3:20 A PRELIMINARY BIOCHEMICAL CHARACTERIZATION OF OXALATE OXIDASE FROM CERIPORIOPSIS SUBVERMISPORA **, Daniel Sledge *, Crystal Bruce * and Ellen W. Moomaw, Gainesville State College, Oakwood, GA 30566. Oxalate degrading enzymes have either actual or potential commercial significance with applications in medicine, agriculture, and industry. Oxalate oxidase and oxalate decarboxylase are used in clinical assays of oxalate in blood and urine. Transgenic plants have been engineered to express oxalate degrading enzymes as a means of protection against pathogens and to reduce the amount of oxalate present. Other applications include the bioremediation of oxalate waste, the production of hydrogen peroxide, and pulping in the paper industry. These uses and the desire to elucidate the novel chemistry that these enzymes catalyze, make them worthy subjects of study. Since recombinant oxalate oxidase from Ceriporiopsis subvermispora (CsOxOx) has not been previously purified beyond 40%, no steady-state kinetic analyses have been previously performed. The native enzyme is reported to possess optimal activity at pH 3.5 and 45[degrees]C. Km and kcat values were reported to be 0.1 mM and 88 s (.sup.1), respectively. Our procedure with the purified recombinant enzyme is to carry out OxOx assay reactions containing specific substrate concentrations in triplicate and the initial rate data is analyzed to obtain the values of kinetic constants by curve fitting using standard computer-based methods. (This project was supported by NSF Grant # MCB-0919908.)

3:40 THE USE OF FLAME ATOMIC ABSORPTION SPECTROSCOPY (FAAS) TO DETERMINE THE AMOUNT OF MANGANESE PRESENT IN OXALATE OXIDASE FROM CERIPORIOPSIS SUBVERMISPORA **, Christopher Brooks * and Ellen W. Moomaw, Gainesville State College, Oakwood, GA 30566. Two pieces of indirect evidence support the idea that oxalate oxidase activity from Cerioporiopsis subvermispora (CsOxOx) is Mn-dependent. First, Mn(II) is present in the resting form of recombinant, wild type CsOxOx as observed by electron paramagnetic spectroscopy. Second, the successful expression of soluble and active CsOxOx requires the presence of Mn(II) in the growth medium. On the other hand, other enzymes in the bicupin family appear to be able to employ a variety of metals in catalysis. Characterizing the manganese dependence of CsOxOx is significant to place this enzyme in the context of other oxalate degrading enzymes and that of other cupin proteins. In order to characterize the manganese dependence of CsOxOx, we use FAAS to determine the amount of manganese present in purified samples. (This project was supported by NSF Grant # MCB-0919908.)

4:00 RAMAN SPECTROSCOPIC STUDY OF VARIOUS BIOFUEL SAMPLES **, Kyle Mascaritolo * and James LoBue, Department of Chemistry Georgia Southern University, Statesboro, GA 30460. Raman spectroscopy of various biodiesels was measured to explore its potential as a general diagnostic technique. Raman spectra of canola, peanut, and corn biodiesels and ethyl acetate were generated with an Ar ion gas laser (Coherent Innova 90) at 514 nm and compared with normal mode frequencies computed at the ab-initio 6-31g * level for ethyl acetate. Spectra were detected with an Ocean Optics USB-4000 Spectrometer. Stoke peaks for the biodiesels matched to a high degree with ethyl acetate features in the range of 1000 to 3100 cm-1. Unexplained broad fluorescence was observed for all biodiesels but was not observed for ethyl acetate. Relative peak intensities were compared between 45o polarized light and unpolarized light yielding different intensities for C-H stretching modes. Fluorescence intensity variations caused dramatic shifts in baseline.

4:20 CONTROL STUDIES OF PHOTODYNAMIC ACTIVITY OF 2,3,4-TRIFLUOROTETRAPHENYL PORPHYRIN ** Adegboye Adeyemo (1), Donovan Tucker * (2), Benjamin Callahan (2), Jonathan Bookout (2) and James LoBue (2), (1) Savannah State University Department of Natural Science and Mathematics, Savannah, GA 31404 and (2) Department of Chemistry, Georgia Southern University, Statesboro, GA 30460. To measure photodynamic activity of 2,3,4-triflouro tetraphenyl porphyrin (TPP) a mixture of TPP and 9,10-diphenylanthracene (DPA) was exposed to laser light at 488 nm and 50mW. Change in UV-VIS absorption indicated change in concentration of DPA and TPP. DPA acted as a sacrificial molecule to simulate biological molecules. Previous studies showed a 55%-65% decrease in DPA with 5%-10% decrease in TPP. To validate previous studies, control experiments were run. Chloroform as a solvent could be responsible for our photolysis rates, so photolysis solutions were prepared in methylene chloride and irradiated under the same conditions as previous experiments. A 65% decrease in DPA was observed, eliminating a solvent connection to observed photolyses. A concentration study was performed by decreasing the concentration of porphyrin by half. A 50% decrease in DPA decomposition was observed which appears to be a higher rate of photolysis than expected. Currently, experiments are being done to remove oxygen from the solutions to confirm the role of oxygen in the reactions.

Cunningham Center, Room 312

Ellen Moomaw, presiding
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Author:Moomaw, Ellen
Publication:Georgia Journal of Science
Geographic Code:1U5GA
Date:Mar 22, 2010
Words:1363
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