Reza Ghiladi

Research projects in the Ghiladi group focus on the multiple roles of metal ions in biology and medicine, with the goals of elucidating peroxidase pathways pertinent to disease states, understanding fundamental mechanisms of peroxidases involved in biocatalysis, investigating the limits of protein design and engineering, and the emergence of metallodrugs in pharmaceutical chemistry. Using millisecond stopped-flow UV-visible spectroscopy coupled with Rapid-Freeze-Quench Electron Paramagnetic Resonance (RFQ-EPR) methodologies, we are able to identify the active intermediates responsible for substrate oxidation, oxygenation, and/or modification in Mycobacterium tuberculosis catalase-peroxidase (KatG), Amphitrite ornata dehaloperoxidase (DHP), and Pisum saivum ascorbate peroxidase (APX). By understanding the key steps in each enzyme pathway, we are able to exploit these systems using a combination of directed evolution and unnatural amino acid incorporation to further our efforts in chemoenzymatic synthesis under green chemistry conditions. A newly emerging research area in the Ghiladi lab includes the modification of antimicrobial peptides with photosensitizers to generate peptide-porphyrin bioconjugates amenable for targeted photodynamic therapy (PDT) of tuberculosis (TB), and the investigation of these novel compounds as PDT antiviral agents that are active against HIV.
 
Dr. Ghiladi will facilitate supervising enzyme kinetic studies with an emphasis on peroxidases involved in lignin biosynthesis for this NSF project. For PO kinetics, the typical ordered sequential or the “ping-pong” two substrate rate equations will be used. Key substrates will be tested, and all reaction products will be corroborated and quantified by LC-MS to determine the Km, Vmax, kcat and Ki values. Enzyme assays will be performed both on purified recombinant protein, and in tissue protein-extracts.