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Studies of the Serotonin Type 3A Receptor and the Chemical Preparation of tRNA


Duffy, Noah Hanville (2014) Studies of the Serotonin Type 3A Receptor and the Chemical Preparation of tRNA. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/X1YA-DM13.


This thesis describes studies surrounding a ligand-gated ion channel (LGIC): the serotonin type 3A receptor (5-HT3AR). Structure-function experiments using unnatural amino acid mutagenesis are described, as well as experiments on the methodology of unnatural amino acid mutagenesis. Chapter 1 introduces LGICs, experimental methods, and an overview of the unnatural amino acid mutagenesis.

In Chapter 2, the binding orientation of the clinically available drugs ondansetron and granisetron within 5-HT3A is determined through a combination of unnatural amino acid mutagenesis and an inhibition based assay. A cation-π interaction is found for both ondansetron and granisetron with a specific tryptophan residue (Trp183, TrpB) of the mouse 5-HT3AR, which establishes a binding orientation for these drugs.

In Chapter 3, further studies were performed with ondansetron and granisetron with 5-HT3A. The primary determinant of binding for these drugs was determined to not include interactions with a specific tyrosine residue (Tyr234, TyrC2). In completing these studies, evidence supporting a cation-π interaction of a synthetic agonist, meta-chlorophenylbiguanide, was found with TyrC2.

In Chapter 4, a direct chemical acylation strategy was implemented to prepare full-length suppressor tRNA mediated by lanthanum(III) and amino acid phosphate esters. The derived aminoacyl-tRNA is shown to be translationally competent in Xenopus oocytes.

Appendix A.1 gives details of a pharmacological method for determining the equilibrium dissociation constant, KB, of a competitive antagonist with a receptor, known as Schild analysis. Appendix A.2 describes an examination of the inhibitory activity of new chemical analogs of the 5-HT3A antagonist ondansetron. Appendix A.3 reports an organic synthesis of an intermediate for a new unnatural amino acid. Appendix A.4 covers an additional methodological examination for the preparation of amino-acyl tRNA.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Serotonin Receptor, Unnatural Amino Acid Mutagenesis
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Dougherty, Dennis A.
Thesis Committee:
  • Barton, Jacqueline K. (chair)
  • Stoltz, Brian M.
  • Tirrell, David A.
  • Dougherty, Dennis A.
Defense Date:30 April 2014
Funding AgencyGrant Number
NIHNS 34407
Record Number:CaltechTHESIS:05062014-151417635
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for ch. 2 adapted for ch. 4
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8220
Deposited By: Noah Duffy
Deposited On:16 May 2014 22:43
Last Modified:04 Oct 2019 00:04

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