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Electron transfer through organic and biological molecules


Leigh, Brian Scott (2009) Electron transfer through organic and biological molecules. Dissertation (Ph.D.), California Institute of Technology.


The function of solvent in facilitating long-range coupling in donor/bridge/acceptor complexes is not well understood. There are exceptional challenges inherent to the measurement of the electron transfer coupling properties of solvents. By immobilizing the donor and acceptor in a glass to eliminate the effects of diffusion, statistical methods of analysis can be employed to study electron transfer between randomly dispersed donor and acceptor molecules over long distances. Toluene and 2-methyltetrahydrofuran form glasses that can solubilize donor and acceptor molecules at 77 K. Exponential decay constant of 1.23 per angstrom, for electron tunneling through a frozen toluene glass, and 1.62 per angstrom through 2-methyltetrahydrofuran glass have been found. Identification of the electronic coupling sites on the surfaces of proteins is usually achieved by inspection of a crystal structure. These coupling spots have been experimentally observed by employing mixed self-assembled monolayer electrodes and a variety of mutants. The electron transport protein azurin has a well defined reduction potential on self-assembled monolayer electrodes (0.16 V vs. saturated Ag/AgCl). When a point mutation is made at position 48, electron transfer ceases. This disruption of electron transfer occurs because the mutation forces conformational changes that disrupt a critical hydrogen bond between asparagine-47 and cysteine-112. This hydrogen bond is a key element for electron transfer into and out of the protein.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:azurin; electron transfer; glass; tryptophan
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Mixed availability, specified at file level
Research Advisor(s):
  • Gray, Harry B.
Thesis Committee:
  • Richards, John H. (chair)
  • Gray, Harry B.
  • Lewis, Nathan Saul
  • Marcus, Rudolph A.
Defense Date:15 July 2008
Author Email:bleigh (AT)
Record Number:CaltechETD:etd-08042008-115533
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3015
Deposited By: Imported from ETD-db
Deposited On:13 Aug 2008
Last Modified:26 Dec 2012 02:56

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