Horseradish peroxidase mediated reactions of estrogenic phenols: Quantifying the impact of enzyme-substrate binding

ENVR 2

Lisa M. Colosi, lmcolosi@umich.edu1, Qingguo Huang, qingguoh@umich.edu2, and Walter J. Weber Jr.2. (1) Environmental & Water Resources Engineering Program, University of Michigan, Ann Arbor, 2200 Bonisteel Blvd. Rm 1234, Ann Arbor, MI 48109, (2) Department of Chemical Engineering, University of Michigan, 2200 Bonisteel Rm. 1213, Ann Arbor, MI 48109-2099
The initial rates of horseradish peroxidase (HRP)-mediated reactions of 15 aqueous-phase phenolic chemicals were studied. The associated reaction rate constants (kCAT) were found to correlate quantitatively with two independent variables: the energy of the substrate's highest-occupied molecular orbital (EHOMO), defining the intrinsic redox reactivity of the substrate and the distance between the substrate's phenolic proton and the δN of HIS42's imidazole in a binding complex obtained through molecular simulation (µHIS). Highly correlated quantitative structure-activity relationship (QSAR) equations were thus developed. This work provides insights into the impact of HRP/substrate binding on the rate of HRP-mediated reactions. Additionally, the QSAR equations developed in the work may serve as a basis to further explore the potential use of HRP-mediated reactions in the treatment of estrogenic contaminants. Following validation of µHIS, they may constitute an important tool for re-designing modifications to the wild-type HRP intended to enhance reactivity toward selected substrates.
 

Catalysis for Water Purification and Remediation
8:30 AM-11:50 AM, Sunday, 10 September 2006 Moscone Center -- Room 206, Oral

Division of Environmental Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006