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Biological electron transfer in copper proteins


Kiser, Cynthia N (1998) Biological electron transfer in copper proteins. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/PWWP-AS34.


Nature has used a variety of protein systems to mediate electron transfer. In this thesis I examine aspects of the control of biological electron transfer by two copper proteins that act as natural electron carriers.

In the first study, I have made a mutation to one of the ligand residues in the azurin blue copper center, methionine 121 changed to a glutamic acid. Studies of intramolecular electron transfer rates from that mutated center to covalently attached ruthenium complexes indicate that the weak axial methionine ligand is important not only for tuning the reduction potential of the blue copper site but also for maintaining the low reorganization energy that is important for fast electron transfer at long distances.

In the second study, I begin to examine the reorganization energy of the purple copper center in the CuA domain of subunit II of cytochrome c oxidase. In this copper center, the unpaired electron is delocalized over the entire binuclear site. Because long-range electron transfer into and out of this center occurs over long distances with very small driving forces, the reorganization energy of the CuA center has been predicted to be extremely low. I describe a strategy for measuring this reorganization energy starting with the construction of a series of mutations introducing surface histidines. These histidines can then be labeled with a series of ruthenium compounds that differ primarily in their reduction potentials. The electron transfer rates to these ruthenium compounds can then be used to determine the reorganization energy of the CuA site.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Plasticyanin, azurin, CuA
Degree Grantor:California Institute of Technology
Major Option:Biology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Richards, John H.
Thesis Committee:
  • Unknown, Unknown
Defense Date:8 January 1998
Record Number:CaltechTHESIS:04212014-115617853
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8194
Deposited By: Dan Anguka
Deposited On:21 Apr 2014 19:56
Last Modified:09 Nov 2022 19:19

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