Interaction and reaction of the hydroxyl ion with beta-D-galactose and its hydrated complex: an ab initio molecular dynamics study

Abstract:

The interaction of OH- with the sugar beta-D-galactose is studied computationally, with Ab Initio Molecular Dynamics (AIMD) as the prime tool. The main findings are: (1) the OH- abstracts a proton from the sugar in a barrier-less process, yielding H2O and a Deprotonated beta-D-Galactose anion, (Dep-beta-D-G)(-). (2) This reaction can be reversed when two additional H2O molecules are present in the sugar. (3) At 500 K, a ring-opening reaction occurs in (Dep-beta-D-G)(-) within a timescale of 10 ps. The (neutral) sugar itself is stable over this timescale, and well beyond. This indicates that OH- can catalyze the degradation of beta-D-galactose. Implications of this process are briefly discussed.