Pathways: Our tunneling pathway
model for protein electron transfer reactions provides a framework
for understanding the dependence of these rates on 3D structure.
Ongoing studies of macromolecule electron transfer are aimed at:
(1) determining the differences between
DNA and protein electron transfer; (2)
understanding how proteins control intermolecular (protein-protein)
electron transfer; (3) obtaining "ab
initio quality" estimates of donor-acceptor interactions in
proteins and DNA via molecular fragment approaches and large
scale self-consistent field computations.
energy transduction: We
are exploring the molecular mechanisms that explain how the energy
of biological transmembrane electrochemical gradients is captured
and converted (by ATP synthase) into discrete energy-storing chemical
bonds. We are also examining how the energy stored in ATP is later
extracted in biosynthesis to drive, for example, electron transfer
in proteins like nitrogenase.
catalysis: Many catalytic processes
in biology involve the delivery of multiple electrons. investigation
of multi-electron redox events are underway, with the aim of understanding
the activation of small substrates (N2, CO2, etc.). Our present
goal is to determine the regimes and activation barriers for sequential,
concerted, or intermediate electron transfer processes.
A new direction of our research focuses on
the intersection of chemistry and micro/nano-electronics (in collaboration
with Dave Waldeck at the University of Pittsburgh and Ron Naaman
at the Weizmann Institute). We are exploring the chemical control
of electron flow through two novel hybrid electronic devices: molecular
controlled semiconductor resistors and negative differential resistance
devices. We are also exploring the transmissio of spin-polarized
electrons through molecular films.
of absolute stereochemistry by computation:
In another exciting interdisciplinary
collaboration, we have joined forces with the Wipf group (University
of Pittsburgh) for the computational assignment of relative and
absolute stereochemistry in complex organic molecules. Recent developments
have enabled the detailed probing of how molecular conformational
influences optical rotation, and how specific chemical groups influence
the optical rotation. In addition to expanding the methodologies,
we are now exploring the nature of optical rotation in oriented
media, to supplement earlier studies of isotropic solutions.