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THE INTERACTION OF PHOTO-RESPONSIVE SURFACTANTS WITH BIOLOGICAL MACROMOLECULES
by
Khiza L. Mazwi
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(MATERIALS SCIENCE)
December 2012
Copyright 2012 Khiza L. Mazwi
Object Description
| Title | The interaction of photo-responsive surfactants with biological macromolecules |
| Author | Mazwi, Khiza L. |
| Author email | mazwi@usc.edu;khiza.mazwi@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Materials Science |
| School | Viterbi School of Engineering |
| Date defended/completed | 2012-07-19 |
| Date submitted | 2012-08-21 |
| Date approved | 2012-08-21 |
| Restricted until | 2012-08-21 |
| Date published | 2012-08-21 |
| Advisor (committee chair) | Lee, C. Ted, Jr. |
| Advisor (committee member) |
Goo, Edward K. Langen, Ralf |
| Abstract | The interaction of photo-responsive surfactants with proteins has been considered as a means to exert reversible control over a number of aspects of protein structure and function. The azobenzene trimethylammonium bromide (azoTAB) family of cationic surfactants undergo a photo-reversible cis to trans isomerization upon exposure to light of the appropriate wavelength. The trans form of the molecule has a lower dipole moment across its azo linkage, and is more hydrophobic than the cis isomer. This results in a higher binding affinity with proteins for the trans isomer, inducing a greater degree of unfolding of tertiary and secondary structures. The surfactant has been applied to the study of the amyloid fibrillation pathway in insulin, in which the protein self-associates into long, insoluble, rod-like structures. The fibrillation rate in insulin is enhanced in the presence of the trans- isomer while the formation of fibrils is largely inhibited in the presence of the cis- isomer, where amorphous aggregates are observed instead. Additionally early fibrillar species formed in the trans-azoTAB assays exhibit a greater tendency to lateral aggregation than do structures in the pure protein, resulting in a more truncated, bundled final aggregate morphology. Use of the surfactants as a means to control protein quaternary solution structure has also been explored in the subunit dissociation of tetrameric catalase. In the presence of azoTAB surfactants, catalase dissociates first into a super-active dimer, then at higher concentrations into an aggregation prone monomer. Finally, the structural changes associated with azoTAB-induced unfolding of the two domain protein papain are tracked. The denaturation pathway involves a progressive loss in secondary structure with increasing azoTAB concentration, along with a relaxation of the compact tertiary structure, and a spatial separation of the two domains. A number of complementary experimental techniques are combined to determine the solution structure of non-native protein conformations, including light scattering, circular dichroism and small angle neutron scattering. |
| Keyword | protein; surfactant; amyloid; neurodegeneration; structure-function; enzyme; azoTAB; Photo-responsive |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m |
| Contributing entity | University of Southern California |
| Rights | Mazwi, Khiza L. |
| Physical access | The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given. |
| Repository name | University of Southern California Digital Library |
| Repository address | USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA |
| Repository email | cisadmin@lib.usc.edu |
| Archival file | uscthesesreloadpub_Volume4/etd-MazwiKhiza-1158.pdf |
Description
| Title | Page 1 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | THE INTERACTION OF PHOTO-RESPONSIVE SURFACTANTS WITH BIOLOGICAL MACROMOLECULES by Khiza L. Mazwi A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (MATERIALS SCIENCE) December 2012 Copyright 2012 Khiza L. Mazwi |
