Theses and Dissertations


Mingjie Li

Issuing Body

Mississippi State University


Emerson, Joseph P.

Committee Member

Lewis, Edwin A.

Committee Member

Fitzkee, Nicholas C.

Committee Member

Gwaltney, Steven R.

Committee Member

Mlsna, Todd E.

Date of Degree


Document Type

Dissertation - Open Access



Degree Name

Doctor of Philosophy (Ph.D)


College of Arts and Sciences


Department of Chemistry


Nonheme iron(II) oxygenases within a common 2-His-1-carboxylate binding motif catalyze a wide range of oxidation reactions involved in biological functions like DNA repair and secondary metabolic processes. The mechanism of O2 activation catalyzed by this enzyme family has been examined by spectroscopic, crystallographic, and computational studies, where it is clear the iron(II) center works with substrate, and cosubstrate to activate O2 by forming a highly oxidizing iron species (iron(IV)-oxo). From a thermodynamic perspective, substrate and/or co-substrate binding organizes the active site for O2 activation, and understanding the interactions among metal, substrate, cosubstrate, and enzyme provides insight into the intramolecular contacts that guide the reaction catalyzed by the enzymes. This dissertation is focused on elucidating the interactions between metal, substrate, and co-substrate in a representative enzyme subfamily of nonheme iron(II) oxygenases, namely the 2-oxoglutarate dependent dioxygenases. Specifically, we investigated the thermodynamic properties of divalent metal ions binding to taurine-dependent dioxygenase (TauD), using Mn2+, Fe2+, and Co2+ ions. Additionally, the thermodynamics associated with substrate and co-substrate binding to Fe·TauD and iron(II)-ethylene forming enzyme (Fe·EFE) were explored using calorimetry and other biophysical techniques.