Photochemistry of light-responsive proteins
Light-responsive proteins have evolved to use light to drive complex processes ranging from
photosynthesis to vision. These systems not only serve as an inspiration for technology but have
also been implemented directly in biotechnologies such as bioimaging, biosensing, optogenetics,
and photodynamic therapy. However, engineering photoreceptors for use in biotechnology requires
a fundamental understanding of how these systems operate on a molecular level. To this end, we
use quantum mechanics and molecular mechanics to understand how biological systems respond
to light. A family of proteins we are currently interested in are light-oxygen-voltage (LOV) domains.
Investigating new classes of fluorescent proteins
Flavin-binding fluorescent proteins (FbFPs) and bilin-binding fluorescent
proteins (BbFPs) are recently engineered classes of fluorescent proteins that
have attractive properties. In particular, in comparison to green fluorescent
protein (GFP) derivatives, FbFPs are smaller (less genetic content to express)
and work in anaerobic conditions, while BbFPs have shown significant promise
recently as far-red or near-IR FPs for deep tissue imaging. We will employ
hybrid quantum mechanical /molecular mechanical (QM/MM) models to
investigate the spectral tuning mechanism and photophysics of these systems.
Modeling of photoelectron spectra
Photoelectron spectroscopy and photoelectron imaging are powerful techniques for probing the
electronic structure of molecules and ions. Time-resolved photoelectron spectroscopy, for instance,
has been employed to probe the evolving electronic character of the system through all
participating states directly. However, the interpretation of such experiments is often aided by
theoretical modeling. We are developing and applying tools for simulating and interpreting
photoelectron spectroscopy and imaging experiments.
Other problems in photochemistry
One main focus of our research is to investigate how an environment, be it
solvent or protein, tunes the photophysical/photochemical properties of a
chromophore. To this end, we often employ electrostatic tuning maps (ETMs),
which represent in an intuitive way the effect of surrounding charges on a
chromophore's properties.
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