Protein electrical properties have been studied using dielectric relaxation measurements throughout the past century. These measurements have advanced both the theory and practice of liquid dielectric spectroscopy and have contributed to understanding of protein structure and function. In this dissertation, the relationship between permittivity measurements and underlying molecular mechanisms is explored. Also presented is a method to take molecular structures from the Protein Data Bank and subsequently estimate the charge distribution and dielectric relaxation properties of the proteins in solution. This process enables screening of target compounds for analysis by dielectric spectroscopy as well as better interpretation of protein relaxation data. For charge estimation, the shifted pKa values for amino acid residues are calculated using Poisson-Boltzmann solutions of the protein electrostatics over varying pH conditions. The estimated internal permittivity and estimated dipole moments through shifted pKa values are then calculated. Molecular dynamics simulations are additionally used to refine and approximate the solution-state conformation of the proteins. These calculations and simulations are verified with laboratory experiments over a large pH and frequency range (40 Hz to 110 MHz). The measurement apparatus is improved over previous designs by controlling temperature and limiting the electrode polarization effect through electrode surface preparation and adjustment of the cell's physical dimensions. The techniques developed in this dissertation can be used to analyze a wide variety of molecular phenomena experimentally and computationally, as demonstrated through various interactions amongst avidin, biotin, biotin-labeled and unlabeled bovine serum albumin, beta-lactoglobulin, and hen-lysozyme.
College and Department
Ira A. Fulton College of Engineering and Technology; Electrical and Computer Engineering
BYU ScholarsArchive Citation
Mellor, Brett Lee, "Liquid Dielectric Spectroscopy and Protein Simulation" (2012). All Theses and Dissertations. 3661.
dielectric spectroscopy, proteins, dipole moment, electrostatics, capacitance, permittivity, molecular dynamics, molecular interactions, protein aggregation