Abstract

The interaction of proteins with surfaces is a major process involved in protein microarrays. Understanding protein-surface interactions is key to improving the performance of protein microarrays, but current understanding of the behavior of proteins on surfaces is lacking. Prevailing theories on the subject, which suggest that proteins should be stabilized when tethered to surfaces, do not explain the experimentally observed fact that proteins are often denatured on surfaces. This document outlines several studies done to develop a model which is capable of predicting the stabilization and destabilization of proteins tethered to surfaces. As the start point of the research, part of this research showed that the stability of five mainly-alpha, orthogonal-bundle proteins tethered to surfaces can be correlated to the shape of the loop region where the tether is placed and the free rotation ability of the part of proteins near surfaces. To test the expandability of the protein stability prediction pattern derived for mainly-alpha, orthogonal-bundle proteins, same analysis is performed for proteins from other structure motifs. Besides the study in these small two-state proteins, a further analysis of surface-induced change of folding mechanism is also studied with a multi-state lysozyme protein 7LZM. The result showed that by tethering a protein on a surface, the melting temperature of a part of the protein changed, which leads to an avoidance of the meta-stable state. Besides the change of folding mechanism, by tethering the lysozyme protein to a certain site, the protein could both keep a stable structure and a good orientation, allowing active sites to be available to other proteins in bulk solution. All the work described above are done with a purely repulsive surface model which was widely used to roughly simulate solid surfaces in protein microarrays. For a next-level understanding of protein-surface interactions, a novel coarse-grain surface model was developed, parameterized, and validated according to experimental results from different groups. A case study of interaction between lysozyme protein 7LZM and three types of surfaces with the novel model has been performed. The results showed that protein stabilities and structures are dependent on the types of surfaces and their different hydrophobicities. This result is consistent with previously published experimental work.

Degree

PhD

College and Department

Ira A. Fulton College of Engineering and Technology; Chemical Engineering

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2013-03-19

Document Type

Dissertation

Handle

http://hdl.lib.byu.edu/1877/etd6097

Keywords

simulation, thermodynamics, tertiary structure, interaction, protein microarray

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