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Computational Studies on the Free Energies of Water Permeation: Effect of Acyl Chain Length and Unsaturation of Monoglycerides

Mariama Njie1*, Sunghee Lee1 and Rodney Versace1*
  • 1 Iona College, United States

A deeper understanding of unassisted passive transport processes can better delineate basic lipid dynamics in biological membranes. Computer simulations have been successfully used to provide atomic details describing water transport process. When combined with experimental data, this will add even more depth to understanding transport and permeation processes at a molecular level. This presentation focuses on computational simulations, where we have investigated the effect of acyl chain structure of amphiphilic monoglycerides on the osmotic permeability of water across DIB membranes composed of these monoglycerides, where the acyl chain length (C14−C20) and number of double bonds (1−4) are varied systematically along the acyl chains. The free energies of water permeation process were determined using the adaptive biasing force (ABF) method, a technique used to determine the free energy of a particular molecule along a z-axis reaction coordinate. The simulation effectively modeled the pulling of a water molecule through the monoglyceride membrane along this axis. As the free energy of a molecule at a particular temperature is postulated to be directly proportional to its activation energy, the free energies of the molecules obtained from the computational simulations were later compared with values obtained from the experimental activation energies. The results, both from computational and experimental methods, allow us to make ready comparisons between the different lipids and potentially better elucidate the contributions that molecular motifs make to the permeation process.

Acknowledgements

Total gratitude goes to the Chemistry Department of Iona College, especially Dr. Rodney Versace, Dr. Sunghee Lee and The Project Symphony. We are also grateful for the support from the Iona College CSTEP program.

References

1) James C. Phillips, Rosemary Braun, Wei Wang, James Gumbart, Emad Tajkhorshid, Elizabeth Villa, Christophe Chipot, Robert D. Skeel, Laxmikant Kale, and Klaus Schulten. Journal of Computational Chemistry, 2005, 26:1781-1802. 2) S. Jo, T. Kim, V.G. Iyer, and W. Im; J. Comput. Chem., 2008, 29:1859-1865 3) Humphrey, W., Dalke, A. and Schulten, K.; J. Molecular Graphics, 1996, vol. 14, pp. 33-38. 4) Klauda, J. B.; Venable, R. M.; Freites, J. A.; O’Connor, J. W.; Tobias, D. J.; Mondragon-Ramirez, C.; Vorobyov, I.; MacKerell, A. D.; Pastor, R. W.; J. Phys. Chem. B 2010, 114, 7830–7843. 5) Darve and Pohorille; J. Chem. Phys. 2001 6) Darve, Rodriguez-Gomez and Pohorille; J. Chem. Phys. 2008. 7) Lopez, M.; Evangelista, S.E.; Morales, M.; Lee, S.; Langmuir, 2017

Keywords: Monoglyceride, computational Simulation, permeation, Lipids, free energy

Conference: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference , Orlando, Florida, United States, 17 Sep - 20 Sep, 2018.

Presentation Type: Poster Presentation

Topic: Computational Chemistry

Citation: Njie M, Lee S and Versace R (2019). Computational Studies on the Free Energies of Water Permeation: Effect of Acyl Chain Length and Unsaturation of Monoglycerides. Front. Chem. Conference Abstract: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference . doi: 10.3389/conf.fchem.2018.01.00047

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Received: 28 Sep 2018; Published Online: 17 Jan 2019.

* Correspondence:
Ms. Mariama Njie, Iona College, New Rochelle, United States, mnjie1@gaels.iona.edu
Dr. Rodney Versace, Iona College, New Rochelle, United States, rversace@iona.edu