Off-campus University of Richmond users: To download campus access theses, please use the following link to log in to our proxy server with your university username and password.

Date of Award

Spring 2013

Document Type

Restricted Thesis: Campus only access

Degree Name

Bachelor of Science

Department

Biochemistry & Molecular Biol.

First Advisor

Dr. Michelle L. Hamm

Abstract

2’-deoxyguanosine (dG) can react with reactive oxygen species (ROS) produced by chemical carcinogens, radiation, and metabolic respiration to form 8-oxo-2’-deoxyguanosine (OdG). While dG inherently base-pairs with 2’-deoxycytidine (dC), OdG can pair with similar stability to either dC or 2’-deoxyadenosine (dA). Should dA be incorporated opposite OdG, the subsequent round of DNA replication will yield the incorporation of dT opposite dA, producing a dG→T transversion. Differences among DNA polymerases’ active sites control the efficiency with which dATP and dCTP are inserted opposite OdG. Incorporation and extension experiments with exonuclease deficient Klenow Fragment (KF-exo; KF-), an A-family polymerase, and human DNA Polymerase β (pol β), an X-family polymerase, were used to investigate these differences. The exact electrostatic and steric characteristics that direct the varying efficiencies of dATP or dCTP incorporation opposite OdG and extension past either OdG:dA or OdG:dC were analyzed using OdG analogues. Results showed that the size of the atom at the C8 position, the protonation of the N7 position, the presence of the C2-exocyclic amine, and interactions between amino acid residues and the XdG:dNTP complex can alter the efficiencies of incorporation and extension with different tolerances seen for KF- and pol β.

Download

Share

COinS