- Metal-catalyzed redox processes of biological importance
- Peroxidases and redox signaling
- Bioinorganic chemistry of nitric oxide and related compounds
- Metalloprotein structure-function relationships
- Development of mass spectrometric techniques to probe cellular communication
We are interested in how small, redox-active molecules such as nitric oxide and hydrogen peroxide (H2O2) control the functioning of cells. Cellular H2O2 levels are tightly controlled by enzymes called peroxidases. To understand the role of H2O2 in cell signaling, we are investigating yeast strains unable to produce certain peroxidases and strains that produce mutant peroxidases. We also study purified peroxidises, such as cytochrome c peroxidase, in vitro to help understand their mode of action in vivo. The goals of this work is to shed light on how H2O2 controls cellular responses to hormone and other stimuation, and how organisms deal with oxidative stress, which is a contributing factor in aging and in many age-related diseases.
Nitric oxide (NO) influences key biological functions including vasodilation, neuronal signaling and the immune response. These processes involve the production of very low amounts of NO in specific cells and tissues, and in the delivery of NO to distant sites. We would like to understand how NO exerts its influence by chemically modifying proteins such as hemoglobin and peptide hormones such as oxytocin, which can profoundly affect their biological actions. We are particular interested in metalloprotein-catalyzed processes that promote NO-transfer between biomolecules. These studies are critical in our understanding of the molecular underpinnings of cardiovasuclar disease and neurodegeneration.
We are also interested in crosstalk between signaling pathways involving H2O2, NO and calcium. We investigate how metalloproteins might promote such crosstalk and have shown, for example, that calcium influences the S-nitrosation of calbindin D28k, an abundant calcium-binding protein in the brain. We also study structure-function relationships in metalloproteins and are particularly interested in probing additional biological functions of well-characterized proteins such as copper-zinc superoxide dismutase and peptides such as oxytocin in cell communication.
Mass spectrometry has become a major tool in our investigations. Posttranslational protein modifications by NO and H2O2, for example, are critical in cells and can be readily characterized using mass spectrometers with electrospray and MALDI sources. We are searching for novel metalloproteins and for novel functions of metalloproteins using ICP-MS.
In addition to mass spectrometry, we use a variety of spectroscopic (FTIR, UV-VIS, fluorescence, CD, EPR), chromatographic (HPLC, FPLC) kinetic (stopped-flow, flash photolysis), thermochemical (isothermal titration calorimetry), microscopy (fluorescence and confocal), and molecular biology techniques.