A Molecular View of Hydration Dynamics Near a Model Peptide
Teresa Head-Gordon,
Department of Bioengineering,
UC Berkeley
New experimental techniques such as wide-angle neutron and quasi-elastic
neutron scattering, third generation x-ray synchrotrons, accompanied
by interpretation and analysis using molecular dynamics, have emerged
for characterizing the structure and dynamics of complicated solvent
environments near biological macromolecules and interfaces. How these
solvents and co-solvents influence protein function or mediate
protein-protein interactions have numerous connections to our
understanding of the fundamental aspects of cellular function,
self-assembly in bio-inspired nanomaterials and in high-throughput
protein technologies and bioprocessing. Unfortunately, experimental
studies of solvent influences on self-assembly and organization have
been relatively rare and not systematic. One of the principal limitations
is that techniques able to investigate solution organization or
solvation dynamics give highly averaged information over all different
kinds of molecular interactions, with a variety of time scales and
length scales. To address these limitations, we have developed a
well-defined model system based on amino acid monomers in solution
that permits us to dissect interactions over nanometer length scales
and picosecond time scales. This model system investigates the evolution
of solution structure and dynamics by varying amino acid concentration,
thereby modeling how the solvent behaves under dissociating conditions
when the local concentration of amino acids is relatively dilute, while
more concentrated solutions describe the consequences of hydration near
assembled solute states or at protein-protein interfaces when the local
concentration of amino acids is very high. In this talk I will place
our QENS measurements on model biological solutes in the context of
other spectroscopic techniques, and provide both confirming as well
as complementary dynamical information that attempts to give a unifying
molecular view of hydration dynamics signatures near peptides and proteins.
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