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PHOTOCONTROL OF PROTEIN CONFORMATION AND
ENZYME ACTIVITY IN THE PRESENCE OF
LIGHT-RESPONSIVE SURFACTANTS
by
Panteha Mirarefi
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
(CHEMICAL ENGINEERING)
December 2010
Copyright 2010 Panteha Mirarefi
Object Description
| Title | Photocontrol of protein conformation and enzyme activity in the presence of light-responsive surfactants |
| Author | Mirarefi, Panteha |
| Author email | mirarefi@usc.edu; panteamirarefi@yahoo.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Chemical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2010-10-08 |
| Date submitted | 2010 |
| Restricted until | Unrestricted |
| Date published | 2010-12-14 |
| Advisor (committee chair) | Lee, Ted |
| Advisor (committee member) |
Shing, Katherine S. Lu, Jia Grace |
| Abstract | Photo-responsive surfactants along with light illumination have been utilized to approach a novel light-based technique to reversibly control dynamic-form-function relationship of enzymes. The photosurfactant, namely azoTAB, undergoes a reversible photoisomerization from the relatively-hydrophobic trans isomer under visible light to the relatively-hydrophilic cis isomer upon UV illumination. The more hydrophobic trans form of the surfactant has a higher binding affinity for proteins and, hence, induces a greater degree of protein unfolding compared to the cis isomer. Therefore, the photoreversibility of the surfactant provide the ability to reversibly control enzyme-surfactant interactions. Photocontrol of the structure and function of carbonic anhydrase has been investigated. Carbonic anhydrase dramatically unfolds in the presence of the trans-surfactant while only a small degree of unfolding is observed upon UV illumination. Consequently, the enzyme is completely inactivated in the presence of the trans-surfactant, but performs some of its original function under UV light, providing a photoreversible on/off switch of enzyme activity.; Photocontrol of the dynamic-form-function relationship of RNase A and lysozyme has also been studied, indicating that both enzymes undergo partial unfolding and exhibit superactivity in the presence of the trans-surfactant. However both protein unfolding and superactivity is reversed back to a native-like condition with UV illumination. One of the advanced applications of the photosurfactant is to dissociate enzyme/inhibitor complexes in order to reactivate enzymes. The effect of azoTAB on RNase A/RI complex has been examined. RI is a strong inhibitor of RNase A and RNase/RI is known as one of the tightest enzyme/inhibitor complexes. In the presence of the trans-surfactant, RNase/RI complex dissociates, leading to RNase A reactivity. The complex dissociation occurs through protein unfolding, mainly RI unfolding. Therefore, RNase inhibition can be reversed to native-like activity upon addition of the trans-surfactant. Altogether, photo-responsive surfactants combined with light illumination can be used as a mean to reversibly photocontrol the structure, dynamic, and function of enzymes, as well as to photocontrol of enzyme/inhibitor complexes. |
| Keyword | protein folding; enzyme function; light-responsive surfactant |
| 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-m3599 |
| Contributing entity | University of Southern California |
| Rights | Mirarefi, Panteha |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Mirarefi-4203 |
| Archival file | uscthesesreloadpub_Volume51/etd-Mirarefi-4203.pdf |
Description
| Title | Page 1 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | PHOTOCONTROL OF PROTEIN CONFORMATION AND ENZYME ACTIVITY IN THE PRESENCE OF LIGHT-RESPONSIVE SURFACTANTS by Panteha Mirarefi 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 (CHEMICAL ENGINEERING) December 2010 Copyright 2010 Panteha Mirarefi |
