Bulletin of the American Physical Society
2018 Annual Meeting of the APS Four Corners Section
Volume 63, Number 16
Friday–Saturday, October 12–13, 2018; University of Utah, Salt Lake City, Utah
Session E03: BIO1: Molecular Machines and Biomechanics |
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Chair: Vanessa Huxter, University of Arizona Room: JFB 103 |
Friday, October 12, 2018 1:30PM - 1:54PM |
E03.00001: Allostery and Molecular Machines: Second Secret of Life Invited Speaker: Banu Ozkan Proteins are the most efficient nano-machines and perform a broad range of functions. All of the information necessary for function is encoded in 1-D sequences. Proteins exquisitely translate this code to fold and function, yet deciphering this encoded information remains an open challenge. With the advancement in sequencing techniques, inferring evolutionary record of extant proteins offers a tractable and highly effective solution to better understand the relation between sequence and protein function in order to decipher the 1-D sequence code. This is because evolution in itself has been a single massive ongoing experiment in diversification and optimization of protein sequence-structure-function relation occurring over billions of years.. We have developed a physics-based metric called the Dynamic Flexibility Index (DFI) to study protein evolution. DFI provides us with an opportunity to retrace evolutionary steps which, in turn, have led to structural dynamics analysis of resurrected ancestral proteins. We demonstrated that protein static structures do not need to be modified in order for new function or molecular adaptation to emerge. Proteins may evolve and adapt new function by fine tuning their native state conformational dynamics. These studies provide us a molecular mechanism: Nature utilizes minimum perturbation-maximum response as a principle through the allosteric alteration of the dynamics of the active/catalytic sites by mutating distal positions, rather than introducing mutations on active sites. We also showed that this principle can be used to design proteins with desired function. |
Friday, October 12, 2018 1:54PM - 2:06PM |
E03.00002: Unconventional Diffusion of Microtubule-Associated Cargos Florence Doval, Olaolu Osunbayo, Chris Miles, Babu Reddy, James Keener, Michael Vershinin We examine the near-immotile behavior of individual model cargos driven by mutant NCD Kinesin motors in a minimal microtubule-based system. Although the in vitro system has no cytosolic or cytoskeleton complexity, the cargo motility shows complex behavior. The observed motility is apparently diffusive, but the exact characterization of the diffusivity is shown to depend on lag time as well as environmental factors. We investigate whether this anomalous diffusion can be purely attributed to enzymatic activity of the NCD N340K motors. |
Friday, October 12, 2018 2:06PM - 2:30PM |
E03.00003: A journey with bacteria: from waste to nematic colloids and gels and to smart windows Invited Speaker: Ivan I Smalyukh Heating, ventilation, and air conditioning of buildings account for about 15% of the global energy consumption, but about 20% of this building-related energy is lost because of inefficient windows. Greenhouse emissions associated with producing and using this energy contribute substantially to climate change. Is there a solution to this challenging problem? Starting from the physical principles associated with energy loss through windows, I will describe our development of visibly transparent, infrared-reflecting, thermally super-insulating materials that may replace or retrofit the inefficient windowpanes of residential and commercial buildings. Using many demonstrations, I will discuss how production of such unusual transparent aerogels is aided by bacteria, with the source materials in the forms of waste of food industry and beer wort, to make such smart windows highly affordable. |
Friday, October 12, 2018 2:30PM - 2:42PM |
E03.00004: Experimental investigation of the motion of magnetic particles through high-viscosity fluids Kathrin Spendier, Austin Routt, Philippe M Jones, Karl Johnson, Guy Hagen In pulmonary diseases such as asthma, overproduction of mucus causes airway obstruction. Therapeutic efficacy of current medications remains poor because the mucus barrier poses a significant challenge to effective drug delivery. The presented work investigates the practicality of using vibrating or rotating magnetic particles (MPs ) to move drugs through high-viscosity fluids. Analytical calculations are used to predict the magnetic torque needed to oscillate or rotate barium hexagonal ferrite and iron oxide particles at frequencies from 5-300Hz in high-viscosity fluids ranging from 0.1 to 10 Pa·s. Vibration or rotation of MPs is achieved by wire coils specifically designed to fit within the sample plane of an optical microscope. Optical microscopy in conjunction with image analysis is used to quantify particle rotation and oscillation in hydroxyethylcellulose gel, corn syrup, and glycerol. Fluid viscosity is measured by a falling ball viscometer. Experimental results indicate that magnetic particles ranging from 20-500nm in size form 10μm aggregates in oscillating fields of 1-10mT in magnitude. This particle aggregation requires higher magnetic torques than initially estimated hampering the practicality of using vibrating or rotating MPs to deliver drugs through mucus. |
Friday, October 12, 2018 2:42PM - 2:54PM |
E03.00005: Formalism for coupled equilibria: statistical mechanics and applications Ian Kenney, Bogdan Iorga, Steve Pressé, Oliver Beckstein The thermodynamics of a system of coupled equilibria is determined by the free |
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