OUR RESEARCH is has focused on the study of structure and function of a bacterial heme enzyme responsible for activation of an old antibiotic still used to treat tuberculosis; and to the study of another bacterial enzyme that catalyzes radical reactions. The first enzyme, catalase-peroxidase (KatG, shown as a ribbon model below with active site inlay) from Mycobacterium tuberculosis, activates the antibiotic, isoniazid, producing an intermediate that goes on to form a critical inhibitor of another enzymatic reaction, shutting down the bacteria's ability to synthesize molecules needed for its cell wall. The research involves the application of electron paramagnetic resonance spectroscopy (epr), optical, and resonance Raman spectroscopy to study the structure and reaction mechanism of the enzyme. Stopped-flow spectrophotometry is also applied for identification of intermediates and for study of the kinetics of KatG-catalyzed reactions.

Fig 1.  A ribbon model representation of the KatG homodimer is shown on the left.  The crystal structure of KatG was used to create this image.  The expansion on the right shows a close-up of the active site (Ferric heme) with the important M-Y-W adduct.

Poster presented at ICBIC: International Conference on BioInorganic Chemistry July 2013.

Stoichiometry of the MetTyrTrp-cofactor (MYW) radical

The Equipment