Date of Award

December 2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Advisor(s)

Liviu Movileanu

Keywords

Detergent, Nanopore

Subject Categories

Physical Sciences and Mathematics

Abstract

Membrane proteins are important in many biological functions such as cell-cell recognition, transport, and signaling; yet the study of these proteins is stunted due to their excessive aggregation in aqueous solutions. Detergents have been extensively exploited to mitigate this aggregation, and accomplish this by protecting the hydrophobic exterior of the membrane protein with their hydrophobic tails, while the polar heads of the detergents interact with the surrounding aqueous environment. Although detergents are of fundamental importance in many membrane protein studies, their selection is primarily done by trial and error screening. In this thesis, I will describe a method to utilize steady state fluorescence polarization to look at the desolvation of detergents from various membrane proteins. The overall goal is to create a methodology that can be employed broadly to map the kinetic fingerprints of various detergents with distinct membrane proteins. This map could potentially be used to build a model that would allow for the better selection and design of amphipols and detergents. Using this newly described florescence polarization anisotropy method, I examine the quantitative contributions of the adhesive protein-detergent and the cohesive detergent-detergent interactions for four beta barrel proteins in five distinct detergents. Further highlighting the generalizable nature of this method, I show the feasibility of this method by using two single pass alpha helical membrane proteins SELENOK and SELENOS. Next, we utilize real time kinetic reads of detergent desorption by describing two distinct phases of the desorption process. The kinetic reads allow the exploration of these interactions and the description of the inferred rate constants of association and dissociation of various detergent-protein complexes. Taken together, I will also explore the intricacies of these protein detergent complexes by describing their dependence on both the biophysical architecture of the membrane protein and the physiochemistry of the detergent itself.

Access

Open Access

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