Date of Award


Publication Type

Master Thesis

Degree Name



Chemistry and Biochemistry

First Advisor

Lee, Lana,


Chemistry, Biochemistry.




Bacterial resistance to toxic anions in Escherichia coli is carried on the R773 plasmid. The plasmid contains the ars operon, which encodes a group of proteins responsible for the extrusion of arsenicals and antimonials out of the cell. One of these proteins, ArsC, has been shown to reduce arsenate (AsO43-) to arsenite (AsO2-) prior to being transported out of the cell (Gladysheva et al., 1994). The protein requires glutathione (GSH) and glutaredoxin in order to reduce the toxic oxyanions. Circular dichroism experiments demonstrated that the secondary structure of ArsC changed marginally when either the substrate or product was present. The melting temperature of ArsC also remained unchanged upon the addition of either arsenate or arsenite. The reduction of arsenate to arsenite by ArsC involves glutathione, glutaredoxin-1, and arsenate. Fluorescence spectroscopy of Trp-mutated ArsC containing 7-azatryptophan was used to probe its interaction with glutaredoxin-1. The results suggest that there is a direct interaction between glutathione with ArsC. There is no change in the fluorescence of the Trp-mutants of ArsC upon the addition of glutaredoxin-1, suggesting that there is no direct interaction of glutaredoxin-1 with ArsC. Source: Masters Abstracts International, Volume: 39-02, page: 0510. Adviser: Lana Lee. Thesis (M.Sc.)--University of Windsor (Canada), 1999.