Structure-Function Studies of Nicotinic Acetylcholine Receptors Using Unnatural Amino Acids and Synthetic Agonist Analogs

• Main Author: Blum, Angela Patricia
• Format: Others
• Published: 2012
• Online Access: https://thesis.library.caltech.edu/6728/13/APBlum-Thesis.pdf; https://thesis.library.caltech.edu/6728/1/APBlum-introduction.pdf; https://thesis.library.caltech.edu/6728/2/APBlum-_CHAPTER_1.pdf; https://thesis.library.caltech.edu/6728/3/APBlum-_CHAPTER_2.pdf; https://thesis.library.caltech.edu/6728/4/APBlum-_CHAPTER_3.pdf; https://thesis.library.caltech.edu/6728/5/APBlum-_CHAPTER_4.pdf; https://thesis.library.caltech.edu/6728/6/APBlum-_CHAPTER_5.pdf; https://thesis.library.caltech.edu/6728/7/APBlum-_CHAPTER_6.pdf; https://thesis.library.caltech.edu/6728/8/APBlum-_CHAPTER_7.pdf; https://thesis.library.caltech.edu/6728/9/APBlum-_CHAPTER_8.pdf; https://thesis.library.caltech.edu/6728/10/APBlum-_APPENDIX_1.pdf; https://thesis.library.caltech.edu/6728/11/APBlum-_APPENDIX_2.pdf; https://thesis.library.caltech.edu/6728/12/APBlum-_APPENDIX_3.pdf; Blum, Angela Patricia (2012) Structure-Function Studies of Nicotinic Acetylcholine Receptors Using Unnatural Amino Acids and Synthetic Agonist Analogs. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/KFPV-JN09. https://resolver.caltech.edu/CaltechTHESIS:11042011-173102026 <https://resolver.caltech.edu/CaltechTHESIS:11042011-173102026>

<p>This dissertation primarily describes structure-function studies of the prototypical Cys-loop ligand-gated ion channel, the nicotinic acetylcholine receptors (nAChRs).</p> <p>Agonists that bind nAChRs, including acetylcholine, nicotine, and the smoking cessation drug varenicline, share one of the longest-known, best-studied pharmacophores, consisting of a cationic N and a hydrogen bond acceptor. A major theme of this thesis is concerned with defining the nAChR residues that bind the nicotinic pharmacophore. Chapters 2 and 3 establish that a hydrogen bond links the pharmacophore’s hydrogen bond acceptor to a backbone NH in the protein. The establishment of this interaction, and the disproval of other predicted interactions, represents the completion of the nicotinic pharmacophore binding model. Chapter 4 uses this model to characterize how the nAChR differentiates between stereoisomers of an agonist.</p> <p>Chapter 5 describes functional studies of a vicinal disulfide that has played a pivotal role in a number of pioneering studies of nAChRs. Despite its historical importance, the functional role of this disulfide has not been defined. We identify a speculative role for the vicinal disulfide that involves the formation of a functionally important network of hydrogen bonds.</p> <p>Chapter 6 outlines three strategies for the photochemical cleavage of protein and peptide backbones using unnatural amino acids. One of these strategies is based on a selenide-mediated cleavage of a backbone ester moiety. Model studies establish the viability of this chemistry and suggest that it could be a useful tool for protein structure-function studies.</p> <p>Chapter 7 concerns preliminary work from a collaboration with laboratories from USC and Caltech that is aimed at developing small-molecule treatments for vision loss associated with photoreceptor degeneration. The initial goal of this project is to develop a photosensitive small molecule that can activate a voltage-gated potassium channel.</p> <p>The final chapter discusses work that was done in the Grubbs lab at Caltech in which a strategy for preparing N-heterocyclic carbene-containing metal complexes was developed.</p>