Carboxyphosphate is a key intermediate in important enzymatic processes, and is computed to be stable in nonpolar environments in a pseudo-chair conformation. However, carboxyphosphate is unstable in aqueous solution, rapidly forming CO2 and Pi through a decarboxylation mechanism. Quantum dynamic simulations of the linear and pseudo-chair conformations of the monoanion and dianion were carried out for 15 ps to investigate the effect of solvent upon the unfolding of conformations and decarboxylation. TeraChem was used with carboxyphosphate surrounded by ~100 waters with spherical boundary conditions using the B3LYP/6-31G(d) functional. The 15 ps QM/MD simulations first show unfolding of the intramolecular hydrogen bond of monoanionic pseudo-chair, followed by C-O bridge bond breakage to CO2 and Pi. The dianion unfolds, but does not decarboxylate. The results of the QM/MD simulation of the monoanion are consistent with the described mechanism and the experimental results, where CO2?is produced during attempts to synthesize carboxyphosphate.

Quantum dynamics simulations of carboxyphosphate unfolding and decarboxylation in aqueous solution

247th National Meeting (2014)

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