Research Projects

Cytochrome P450-containing systems

       We are interested in understanding P450s, one of nature's most versatile biologic catalysts. Cytochromes P450 (P450s) are ubiquitous enzymes catalyzing monooxygenation reactions and playing diverse functional roles in a broad range of biological systems. In mammals they are involved in a variety of biochemical processes including carcinogenesis, drug metabolism, biosynthesis of lipids and steroids or degradation of xenobiotics.
       Currently, our research focuses on cytochrome P450cam (CYP101) from the soil bacteria Pseudomonal putida, the model system of the P450 superfamily. The hydrogen shuttle pathway occurring at the active site during monooxygenation catalysis is a matter of debate. The enhanced visibility of hydrogen and of its deuterium isotope in neutron protein structures suggests that neutron protein crystallography could provide critical information that could help further characterize the proton transfer in the P450cam enzymatic mechanism. The neutron analysis is further extended to putidaredoxin (Pdx) and putidaredoxin reductase (Pdr), the P450cam redox partners, to characterize the two-electron transfer from Pdr to P450cam and through Pdx leading to the activation of the final P450cam component in this monooxygenase system.

Structural Virology
      
      Small-angle neutron scattering (SANS) with contrast variation is ideally suited to the study of large, nested, multi-density, and spherical systems such as viruses in solution. The application of contrast variation makes it possible to highlight different structural elements, thereby understanding the assembly of the whole particle.
      In vitro (pH, ionic environment) driven conformational changes in virus particles can be used to mimic and characterize structural rearrangements that occur upon the activation and infection processes. We are using neutron contrast variation techniques to sequentially track, characterize and model rearrangement undergone by structural virus proteins, lipids, and nucleic acid core respectively.