Year of Award

2019

Document Type

Dissertation - Campus Access Only

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Biochemistry & Biophysics

Department or School/College

Department Chemistry and Biochemistry

Committee Co-chair

J.B. Alexander Ross, Bruce E. Bowler

Commitee Members

Christopher Palmer, Elizabeth A. Putnam, Stephen R. Sprang

Keywords

Cytochrome c, Intrinsic Apoptosis, Protein Lipid Interactions

Publisher

University of Montana

Abstract

The heme protein cytochrome c (cytc) plays a crucial role in the electron transport chain, has been used as a model protein to study protein folding, and more recently has been determined to play a role in initiating apoptosis. The interaction of cytc with the lipid cardiolipin results in initiation of intrinsic apoptosis when, among other things, the oxidation of cardiolipin by cytc increases permeabilization of the mitochondrial membrane. The result of this membrane permeabilization is the release of various proapoptotic factors from the mitochondria including cytc. A domain-swapped dimer (DSD) conformation of cytc from various species has been published by various labs, including the Bowler lab. We postulate that the DSD conformation is a governor or switch that has evolved to allow tighter control over apoptosis. The kinetic stability of the DSD will be presented for multiple species hypothesizing that the human DSD has evolved to be stable enough for biological function. The interaction of cytc with cardiolipin and structural dynamics will be studied using fluorescence correlation spectroscopy, fluorescence anisotropy, circular dichroism, and computer modeling. The data presented will show that the DSD is in a highly competent conformer for increased and efficient peroxidation of cardiolipin. Data examining the functional peroxidase activity will be presented to show that not only is the conformation ideal for peroxidase activity, but there is also a dramatic enhancement of cytochrome c’s activity in the DSD conformation.

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© Copyright 2019 Harmen Bentley Behymer Steele