Ling, Xiujun
(2014)
SYNTHESIS OF PROTEIN FOLDING MODELS AND A MOLECULAR TORSION BALANCE STUDY OF NEIGHBORING GROUP EFFECTS ON HYDROPHOBICALLY DRIVEN FOLDING.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
This project investigated how alkyl group size, functionality, and polarity may affect hydrophobic binding. To complete this investigation, we prepared eleven new torsion balances. The syntheses were convergent, and the synthesis of the most complex torsion balance required 12 steps in the longest continuous path, and 28 steps overall. In this project I developed experimental conditions for 16 new chemical transformations, and characterized 62 new compounds. This project included detailed physical organic investigations. I used NMR spectroscopy to measure the rates and equilibrium constants associated with the folding.
Torsion balances bearing a bicyclo[2.2.2]octyl moiety have higher magnitude (more favorable) folding energies than those that have a trans-cyclohexyl moiety. Modeling studies indicate that this is due to better contacts of the bicyclo[2.2.2]octyl unit compared with the trans-cyclohexyl unit. We observed that the polarity of functional groups nearby the contact surfaces has negligible effect on folding energy. In MeOD, branching functionality resulted in more folding compared to linear functionality. The folding energy in water was higher in water than in MeOD. The difference in folding energy between torsion balances with different contact areas was diminished in D2O. We conclude that London attraction is enhanced more in water for poorly bound surfaces (less contact area) than for tightly bound surfaces (more contact area). In other words, a torsion balance with less contact surface has more room for improvement in the London dispersion energy.
We evaluated the effect of the length of the alkyl group on folding. After a certain point the length of the alkyl group had no effect on folding. Thus, for these small models, excess surface free energy (γ) of the interacting surfaces is not significantly changed as the surface is extended. Lum-Chandler-Weeks theory predicts γ is different among hydrophobic spheres of changing size.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
29 May 2014 |
| Date Type: |
Publication |
| Defense Date: |
14 April 2014 |
| Approval Date: |
29 May 2014 |
| Submission Date: |
17 April 2014 |
| Access Restriction: |
5 year -- Restrict access to University of Pittsburgh for a period of 5 years. |
| Number of Pages: |
183 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Chemistry |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
molecular torsion balance, protein folding, hydrophobic effects, neighboring group effects |
| Date Deposited: |
29 May 2014 17:50 |
| Last Modified: |
29 May 2019 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/21300 |
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