Bulletin of the American Physical Society
2019 Joint Fall Meeting of the Texas Sections of APS, AAPT and Zone 13 of the SPS
Volume 64, Number 18
Friday–Saturday, October 25–26, 2019; Lubbock, Texas
Session B01: Biological and Soft Matter Physics I |
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Chair: Michael Holcomb, Angelo State University Room: Student Union Building Lubbock Room |
Friday, October 25, 2019 10:21AM - 10:33AM |
B01.00001: Protein Structural Fluctuations at Criticality in the Temperature-pressure-crowding Folding Phase Diagram Andrei Gasic, Margaret Cheung In the cell, proteins perform complex biological functions through large-scale motion, which are induced by slight environmental perturbations. This characteristic of having high susceptibility is similar to a physical system near a critical point. Indeed, experimental and computational findings demonstrate that protein folding transitions in the temperature ($T$), pressure ($P$), and crowding volume-fraction ($\phi$) phase diagram point toward signatures of criticality, where distinct folding phases merge. Here, using coarse-grained molecular dynamics simulations, we theoretically show that at the critical regime, fluctuations exhibit high susceptibility and long-range correlations up to the size of the protein. Meaning that near criticality, the dynamics of each residue is influenced by each other residue even across the entire protein. We investigate the structural origin and the effect of macromolecular crowding on this critical behavior. Furthermore, this study leads us one step closer to developing universal principles of protein folding and function in vivo. [Preview Abstract] |
Friday, October 25, 2019 10:33AM - 10:45AM |
B01.00002: Enhancement of the Electrical Properties of DNA Molecular Wires Nolan King Due to its self-assembling properties, DNA has been identified as a promising material for construction of nanoscale electronic devices. In this study, we design and fabricate well-matched and perelyenediimide containing DNA molecular wires, and their electrical properties are characterized. We find PTCDI-containing wires exhibit an approximately 6-fold enhancement in the observed current levels. Additionally, a multiplexed measurement solution is prototyped in order to facilitate the testing of multiple devices at once and reduce the time burden associated with device testing. [Preview Abstract] |
Friday, October 25, 2019 10:45AM - 10:57AM |
B01.00003: Tracking the Metabolic Fates of $^{\mathrm{13}}$C and $^{\mathrm{15}}$N-alanine in Glioblastoma Qing Wang, Sarah Chieng, Christopher Parish, fatemeh Khashami, Lloyd Lumata Glioblastoma is one of the most lethal forms of cancer with a very dismal survival rate. Such tumors are mostly chemoresistant and difficult to detect at an early stage. Thus, there is an unmet clinical need of non-invasive methods for early detection of glioblastoma. In this study, we have investigated the metabolism of $^{\mathrm{13}}$C,$^{\mathrm{15}}$N-labeled alanine in SfXL glioblastoma cells with different incubation times of the substrate using NMR spectroscopy. Our data show high production of $^{\mathrm{13}}$C-lactate from $^{\mathrm{13}}$C-alanine and that the intermediate metabolite $^{\mathrm{13}}$C-pyruvate was not visible in the $^{\mathrm{13}}$C NMR spectra up to 48 hours of incubation time. Consequently, we also track the metabolic fate of $^{\mathrm{15}}$N-amino arm of alanine to complete the metabolic story of this amino acid in cancer. These results suggest that glioblastoma cells prefer rapid lactic acid production from alanine-derived pyruvate, indicative of the hyperactive ALT and LDH activities in these cells. This study is supported by Welch grant AT-1877-20180324, DOD grants W18XWH-17-1-0303 and DOD W81XWH-19-1-0741, CPRIT grant RP180716, and the UTD Collaborative Biomedical Research Award (CoBRA). [Preview Abstract] |
Friday, October 25, 2019 10:57AM - 11:09AM |
B01.00004: $^{\mathrm{13}}$C NMR Spectroscopic Studies of High-Fructose Corn Syrup Metabolism in Cancer Fatemeh Khashami, Chelsea Sanchez, Brianna Royer, Christopher Parish, David Clark, Qing Wang, Kathleen Domalogdog, Lloyd Lumata Increased dietary consumption of sugar has been implicated in a number of clinical pathologies, including obesity and other metabolic diseases. High fructose corn syrup, a sugar mixture of about 40{\%} glucose and 60{\%} fructose, is a ubiquitous sweetening additive used in a wide array of various soft drinks as well as food. In this study, we have closely observed how a particularly aggressive strain of glioblastoma cells, namely \textit{SfXl}, metabolizes both fructose and glucose. The main finding of this preliminary work is that, despite equal caloric content of these two sugars, fructose and glucose metabolized quite differently in this particular cell line of \textit{SfXl} Glioblastoma cells.~$^{\mathrm{13}}$C NMR spectroscopy was used in this study due to high specificity courtesy of the wide chemical shift dispersion of carbon-13. Glioblastoma multiforme (GBM), or cancer of the glial cells, is a highly aggressive and mostly chemoresistant form of brain cancer with a very dismal chance of survival. The primary objective of this study was to investigate the metabolism of fructose and glucose in glioblastoma, given the ubiquity of these two sugars in the western diet and compare our results with liver cancer cell lines \textit{HUH7}. [Preview Abstract] |
Friday, October 25, 2019 11:09AM - 11:21AM |
B01.00005: Isoflurane Increases Cell Membrane Fluidity Significantly at Clinical Concentrations Jigesh Patel There is an on-going debate whether anesthetic drugs, such as isoflurane, can cause meaningful structural changes in cell membranes at clinical concentrations. In this study, the effects of isoflurane on lipid membrane fluidity were investigated using fluorescence anisotropy and spectroscopy. In order to get a complete picture, four very different membrane systems (erythrocyte ghosts, a 5-lipid mixture that mimics brain endothelial cell membrane, POPC/Chol, and pure DPPC) were selected for the study. In all four systems, we found that fluorescence anisotropies of DPH-PC, nile-red, and TMA-DPH decrease significantly at the isoflurane concentrations of 1 mM and 5 mM. Furthermore, the excimer/monomer (E/M) ratio of dipyrene-PC jumps immediately after the addition of isoflurane. Our data indicates that isoflurane is quite effective to loosen up highly ordered lipid domains with saturated lipids. As a comparison of the effects on membranes, the decrease of nile-red fluorescence anisotropy in erythrocyte ghosts by 1 mM isoflurane is more than the corresponding decrease caused by 52.2 mM of ethanol, which is three times the legal limit of blood alcohol level. Our results paint a consistent picture that isoflurane at clinical concentrations causes significant and immediate increase of membrane fluidity in a wide range of membrane systems. [Preview Abstract] |
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