A density functional theory investigation of the fragmentation mechanism of deprotonated asparagine

In this study, the fragmentation mechanism of deprotonated asparagine (Asn) was investigated in detail using density functional theory at the BHandHLYP/6-311 + + G(2df,2pd) level of theory. The H2O-, NH3- and CO2-loss fragmentation reaction profiles constructed by the relative Gibbs free energies of the located stationary points were used to analyze the preferred dissociation pathways and the structures of the resulting molecular ion products. Furthermore, we also examined the temperature dependence of the thermodynamics and kinetics of key dissociation reactions, which provided further insight into the dominant fragmentation channel and the corresponding product distribution under different experimental dissociation energies. This study offered a computational support for building the fragmentation model of deprotonated amino acids.