Molybdenum and tungsten containing metalloenzymes are important to all forms of life, from ancient archaea to man.  These enzymes catalyze important reactions in carbon, sulfur, and nitrogen metabolism and at least 50 enzymes are now known.¹  We are particularly interested in the mechanism of oxotransferases, enzymes that are involved in oxygen atom transfer (OAT) to substrates e.g. oxidation of sulfite to sulfate or reduction of Me₂SO to Me₂S.²  Our contribution to the mechanistic understanding of these important classes of enzymes is made through functional analogues to mimic biological activities.  Currently, we are using the poly(mercaptoimidazolyl)borate³ system complexed to Mo(V) and Mo(VI) in attempt to achieve catalytic activity.  Physical methods applied to the characterization of these metal complexes include single crystal x-ray diffraction, electron paramagnetic resonance (EPR), electrochemistry, UV-Visible electronic spectroscopy, and nuclear magnetic resonance (¹H and ¹³C NMR).

In addition, we are also interested in synthesizing new classes of heteroscorpionate ligands, which incorporate hydrogen-bonding moieties and its  effect on the properties of biologically important metal centers, such as Zn, Mo, and Cu.  Among the various interactions that proteins use to modify the secondary coordination sphere, hydrogen bonding is considered important because of selectivity and specificity control.  While the usage of sterically- restricted ligands to control the size and shape of metal binding cavities is well established, it has proven difficult to incorporate hydrogen bonding into synthetic  analogs.  Relevant properties include things like redox potentials, spectroscopic signatures (i.e. optical, vibrational, NMR, X-Ray, etc), and reactivity.  In addition to organic synthesis techniques, we have utilized the use of modern microwave technology in order to synthesize various types of ligands.

Office: GMCS-209    Office Phone: (619)594-5929    Lab 1 Phone: (619)594-5574    Lab2 Phone: (619)594-5577    Email: carrano@sciences.sdsu.edu