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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. doi:10.7907/EYKS-R134.


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:Public (worldwide access)
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
Non-Caltech 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 Nov 2019 20:37

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