Theoretical modeling of the nonenzymatic solvolysis of CMP-NeuAc in an acidic environment

A density-functional-theory investigation of the nonenzymatic solvolysis of the cytydine 5′-monophosphate N-acetylneuraminic acid and its derivatives in the acidic environment is presented. The theoretical calculations of the second stage of the reaction mechanism are in agreement with the hypothesis of a dissociative oxocarbenium-like transition state with proton transfer as a key part of the reaction. The geometries of the transition states of the reactions yielding α-methyl and β-methyl glycosides are essentially different. This study provides new theoretical data that can be helpful in elucidating the mechanism of the carbohydrates hydrolysis as well as other reactions catalyzed by the glycosyltransferases.