Femtobiology, Biomolecular Interactions, Protein Dynamics
in the Zhong group is directed towards understanding the nature of
elementary processes in biological systems. We relate dynamics and
structures to functions at the most fundamental level with
state-of-the-art femtosecond lasers and molecular biology techniques.
The laboratory ultimately will have the capability of time resolution
from femtosecond to millisecond (second); biological systems can be
prepared and studied at the single molecule level. We are currently
focusing on studies of molecular recognition and ultrafast
protein/enzyme dynamics of several important biological systems.
Biomolecular recognition is governed by physical forces
and the understanding of electrostatic interactions at the atomic
scale is fundamental to protein science. Here, we are particularly
interested in protein-DNA/ligand binding processes and study local
hydration, complex rigidity and conformation dynamics. Intrinsic amino
acid residue tryptophan has been characterized in various biological
environments to probe electrostatic interactions; several important
resonance energy transfer pairs have been developed to study
conformational changes. Molecular mutation is used to investigate
site-specific interactions. These studies are very important to drug
transport and design, protein folding and unfolding, and enzyme
A variety of ultrafast elementary reactions
involved in protein functioning such as twist motion, proton, electron
and energy transfer, and bond breaking and making will be studied.
Site-direct mutagenesis will be used to alter structurally and
chemically important residue(s) to study the local reactivity. These
studies will elucidate the role of dynamics in
structure-dynamics-function correlation and the nature of
non-equilibrium biological dynamics by coherent femtosecond laser
preparation. Currently, we focus on DNA-repair enzymes (photolyases)
to map out the entire evolution of functional processes and thus
reveal the molecular mechanism of this important biological function.
A similar photosensory protein (cryptochrome) is also being studied to
elucidate its key photochemistry for synchronization of biological
timing (circadian rhythm).