Electronic fluctuation in physiological solutions: Trimethylamine N-oxide and tert-butyl alcohol

Although small organic molecules in cells have been considered important to control the functions of proteins, their electronic fluctuation under real physiological conditions has never been clarified due to the lack of observations. Herein, the time evolutions of the interactions in dilute aqueous trimethylamine N-oxide (TMAO) and tert-butyl alcohol (TBA) solutions were analyzed via ab initio molecular dynamics simulations accelerated with the fragment molecular theory. It has been known that TMAO and TBA have similar structures, but opposite physiological functions to stabilize and destabilize proteins. It was clarified that water dipole in the TMAO solutions are up to 1.5 times enhanced that affect protein stabilization. Understanding the solution dynamics will contribute to artificial chaperone design in next generation medicine.