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Title:Supramolecular Architectures in Molecular Medicine: Visualizing and Manipulating the Structure of Protein-Lipid Surfaces
Author(s):Carlson, Joseph W.
Doctoral Committee Chair(s):Sligar, Stephen G.
Department / Program:Biophysics and Computational Biology
Discipline:Biophysics and Computational Biology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):supramolecular architecture
reconstituted high density lipoproteins
Abstract:Molecular complexes play a number of key roles in medicine and biology. Understanding how these complexes behave at interfaces, as well as controlling their structure, is of fundamental interest to science and technology. Lipoproteins, a complex of protein and lipid, serve as the primary transporter of cholesterol and other lipids throughout the body. There is a direct correlation between the presence of certain lipoprotein species and the incidence of coronary artery disease. High density lipoproteins are responsible for the removal of cholesterol from the peripheral tissues and, as such, lead to a reduction in the risk of heart disease. Reconstituted high density lipoproteins have been studied with the atomic force microscope. This microscope has revealed new insight into the structure of these supramolecular aggregates and their interfacial behavior. In order to allow accurate quantitation of lateral size a new imaging standard was developed. This standard, peptide modified colloidal gold, has been used in solution to solve tip induced artifacts and to correct for tip changes simultaneous with sample imaging. A spontaneous fusion process has been observed and examined, revealing the important structural role of apolipoprotein A-I , even in an interfacial setting. These discoidal rHDL have been found to generate a new form of supported bilayer structure which has been particulary amenable to atomic force microscope study and manipulation. The microscope has revealed the bilayer structure of these dises through nanodissection. It has also been used to control the spontaneous fusion process of these dises, resulting in spatially defined bilayer domains of nanometer scale dimensions. By using a source of exogenous lipid in solution the AFM has been used to induce lipid exchange with these surfaces, resulting in a compositional change of the supported bilayer in a spatially controlled manner. A model of this process has been proposed based on defects introduced by the AFM tip binding vesicles, which subsequently fuse with the surface. Finally, the AFM has been used to direct proteins to spatially selected regions, allowing the fabrication of heterogeneous membrane protein containing surfaces. In separate studies, myoglobin has been used to study the fluorescence lifetime behavior of oriented biomolecular surfaces. These studies have revealed differences in lifetime between differentially oriented myoglobin molecules, consistent with differential accessibility of the heme pocket to quenching by oxygen. A computational study of the dependence of linear dichroism on the distribution of protein orientation angle has revealed a constrained degenerate solution, which has impact on ail attempts to describe protein orientation with this technique.
Issue Date:1999
Genre:Dissertation / Thesis
Rights Information:Copyright 1999 Joseph W. Carlson
Date Available in IDEALS:2010-07-01

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