1 research outputs found
Prediction of p<i>K</i><sub>a</sub> Using DFT: the Nicotianamine Polyacid Example
The determination of p<i>K</i><sub>a</sub> values for
molecules containing multiple acidic groups in solution is challenging
both experimentally and theoretically. We propose a general method
to obtain these values by combining a graphical analysis based on
a predominance diagram, for amino acids and nicotianamine polyacid,
with first principle DFT calculations. Implicit and semiexplicit water
solvent models were included to account for solvation. This strategy
enables the investigation of the protonation states of compounds containing
acidic moieties in solution depending on the pH domain. The method
was first validated on a set of amino acids with p<i>K</i><sub>a</sub> values calculated with an accuracy within 0.5ā1.0
p<i>K</i><sub>a</sub> unit and then on the chalenging nicotianamine
polyacid with six p<i>K</i><sub>a</sub> values. This approach
is particularly well suited for such a complex system including both
zwitterionic structures and unknown experimental p<i>K</i><sub>a</sub> values