Stephen G. Sligar

Our research efforts seek a precise understanding of the mechanisms of biological oxidation, the structure of collective assemblies of organized protein, lipid, and nucleic acid systems, the basis of molecular recognition in protein-protein and protein-nucleic acid complexes, and the detailed chemistry and physical operation of oxygenase and oxidase catalysis.

One research focus is on the cytochrome P450-dependent mixed-function oxidases that play central and crucial roles in mammalian, plant, insect, viral, and microbial metabolism. Central questions relating to the mechanisms of these enzymes include the precise chemistry involved in activating oxygen and substrate, and the identity of metal-oxygen-carbon intermediates in the catalytic event, the detailed physical description of inter- and intra-protein electron and proton transfer, and the structure of multi-enzyme membrane complexes involved in catalytic oxygenation and redox movement. We use low-temperature X-ray crystallography as well as cryoenzymology to trap intermediate states. We also are actively pursuing the problems of functional genomics in the large P450 superfamily. Through these efforts we have discovered multiple functions, not only in atmospheric dioxygen metabolism but also via reductive chemistries operating in totally anaerobic environmental niches. We also are investigating protoeomic issues related to thermal and baro-stability and related evolutionary connectivities of human metabolic profiles.

A second focus of our group uses the powerful tools of nanotechnology. As part of the NSF Nanoscale Science and Engineering Center, feedback controlled lithography and dip pen lithograph are being utilized to introduce controlled patterns onto surfaces from the single silicon atom level to the 100 nm scale. We are developing controlled self-assembly processes to generate mesoscale biological assemblies onto these patterned surfaces which can serve as sensors and high throughput screening arrays for pharmaceutical targets. Current efforts introduce single membrane proteins, such as G-protein coupled receptors and human and plant P450 isozymes, into controlled lipid rafts. Readout modalities include surface plasmon resonance, atomic force microscopy and photonic band gap architectures.