The Roth group conducts research of relevance to health, energy and the environment, working at the biology, chemistry and physics interface.
Enzymatic Redox Chemistry: Enzymes catalyze oxidative processes vital to life using redox-active transition metal ions. These are the same species found in minerals, in advanced materials and many industrial processes. In biological systems, they mediate coupled transfers of electrons and protons over moderate distances.
Oxidation-reduction (redox) reactions can be highly selective in protein environments. Isolated radicals are formed at tyrosine side chains in conserved positions among families of proteins, some of which function as enzymes and mediate levels of reactive oxygen species. Tyrosyl radicals also catalyze redox reactions involving substrates and in some cases the surrounding protein. These reactions can be normal/productive or aberrant.
We are examing redox reactions central to life, such as those underlying the biosynthetic utilization of molecular oxygen. The regulation of radicals formed in dioxygenases and enzymes which mediate oxygenic photosynthesis are also of specific interest. Ultimately, we aim to understand how related metalloproteins mediate redox reactions over a range of distances.
Heavy Atom Isotope Effects: The interactions of transition metals with small gaseous molecules (e.g. oxygen bonding to the heme prosthetic group, shown below) are characterized by electron transfer and isotope effects. We have shown how oxygen isotope effects can be precisely measured at natural abundance levels, using competitive techniques and isotope-ratio mass spectrometry and used to interpret chemical structures and reaction mechanisms.
Currently under investigation, are approaches to simultaneously measure and predict heavy atom isotope effects which characterize a range of chemical and biological redox processes. The methods being developed may be applicable to explaining biogeochemical cycles of the elements and oxidative processes within organisms.
Inorganic Catalysis of Water Oxidation: A recurring theme in our research is the origins of catalysis and how inorganic complexes relate to metalloproteins. An important objective is to develop inorganic catalysts that might be able to mediate transformations comparable to metalloproteins. In this effort, we are targeting catalysts involving metal-oxide or metal-oxo intermediates to produce solar hydrogen, in an economically viable manner, as an alternative to fossil fuels.