Vanadium Haloperoxidase

Oxidation of Sulfide by Vanadium Haloperoxidase: A Kinetic Study Mimicking Halide Oxidations

Presenter: Cesar Torres

Presenter Status: Undergraduate student

Academic Year: 22-23

Semester: Spring

Faculty Mentor: Jon Fukuto

Department: Chemistry

Screenshot URL: https://drive.google.com/uc?id=1o3e4owO6FWtifIQ_Qeof5En7bCtwWC1e

Abstract:
The dioxovanadium(V) complex VO2(acac-ambmz) has been synthesized and characterized as a model for the enzyme vanadium haloperoxidase. 1H and 13C NMR spectra have been employed for characterization. Vanadium haloperoxidases are a rare family of enzymes that are mostly known for catalyzing the oxidation of halide ions by hydrogen peroxide, with the formation of a peroxovanadium complex, into hypohalous acids. Haloperoxidases are found in most marine algae, seaweed, lichens, and fungi which are responsible for the production of a large number of halogenated organics in vivo. These serve as effective antibacterial agents. It has recently been discovered that vanadium haloperoxidases are not limited to halide oxidations. In fact, they can also be employed in the catalytic oxidation of sulfides to sulfoxide and sulfone with hydrogen peroxide. The reaction mechanism has been proposed to follow halide oxidations because of the formation of the peroxovanadium intermediate that is essential in order to obtain the catalytic activity. Moreover, this reaction has been shown to be enantioselective and stereoselective. This study focuses on the catalyzed oxidation of thioanisole with hydrogen peroxide to methyl phenyl sulfoxide which is the major product. In addition, the kinetics of the reaction are also monitored via GCMS with methyl p-tolyl sulfide as the internal standard. Determination of the kinetic parameters will give insight into the catalytic activity of vanadium haloperoxidases.