Date of Award
Chemistry and Biochemistry
Trimethylamine N-Oxide (TMAO), guanidinium, and urea are three important
osmolytes with their main significance to the biophysical field being in how they
uniquely interact with proteins. TMAO is known to stabilize and counteract the
destabilizing effects of both urea and guanidinium. The exact mechanisms by which
TMAO stabilizes and both guanidinium and urea destabilize folded proteins continue
to be debated in the literature. Some studies suggest that solvent interactions do not
play a large role in TMAO’s stabilizing effects and therefore advocate direct
stabilization, whereas others suggest that TMAO counteracts denaturation primarily
through an indirect effect of strong solvent interactions. Herein, we use Raman
spectroscopy to elucidate the physical interactions between the osmolytes of interest
in aqueous solutions to better understand how they interact with each other and affect
adjacent hydrogen-bonding networks of water. Comparing experiment to theory yields
good agreement, and it was determined that adding TMAO into both an aqueous
solution of guanidinium and an aqueous solution of urea induces a blue shift (shift to
higher energy) in both urea and guanidinium’s H-N-H bending modes, which is
indicative of direct interactions between the osmolytes.
Verville, Genevieve, "Raman Spectroscopic and Quantum Chemical Investigation of the Effects of Tri-Methylamine N-Oxide (TMAO) On Hydrated Urea, Hydrated Guanidinium, and Hydrogen Bonded Networks" (2020). Honors Theses. 1461.
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