A Density Functional Theory Investigation of the Fragmentation Mechanism of Deprotonated Serine

Abstract

In this paper, density functional theory (DFT) was applied to study the dissociation process of NH3- and H2O-loss reaction of the deprotonate serine ([Ser–H]–) at BHandHLYP/6-31G level. The geometric structure of the isomers, transition states and dissociation products of [Ser–H]– was optimized. The related energy of the material was obtained by frequency calculation, and the potential energy profile of NH3- and H2O-loss reaction was constructed. The possibility and direction of the reaction along different paths were discussed. It is indicated that the stable structure of [Ser–H]– is 1d. In the NH3-loss reaction path, the optimal structure of proton serine isomer is 2j, and the dominant channel is Path 6. The Gibbs energy of the corresponding ration-determined step is 61.88 kcal•mol-1. The optimal structure of [Ser–H]– isomer in H2O-loss reaction is 1i, and its dominant channel is Path 7. The Gibbs activation energy of the corresponding ration-determining step is 74.15 kcal•mol-1. It can be seen that NH3-loss reaction is easier than H2O-loss reaction under this reaction condition.