Understanding disaccharides collision-induced dissociation through extensive theoretical calculations.

Hock-Seng Nguan^1*, Shang-TingTsai³, Chi-Kung Ni^1,2

¹Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
²Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
³Department of Applied Chemistry, National Chiayi University, Chiayi City, Taiwan

* Presenter:Hock-Seng Nguan, email:nguanhs@gmail.com

Carbohydrate structures are highly diverse and complex due to their high density of stereogenic centers and functional groups. The structure determination is a longstanding bottleneck of carbohydrate research, and tandem mass spectroscopy (MS/MS) is the most widely used technique for the structure determination. The amount of the structural information that can be derived from MS/MS depends on how well carbohydrate dissociation mechanisms are understood. Through extensive structural searches and high-level quantum chemistry calculations, we examined the collision-induced dissociation (CID) mechanism of disaccharides with 1-3, 1-4 and 1-6 linkages. With the calculation results, the respective carbohydrates CID spectra obtained from the experimental measurements can be explained. The features of the spectra that related to anomericity and glycosidic bond linkages were identified. Our work gives new insights to the dissociation mechanism of carbohydrates, and helps in the development of our novel MS/MS method for polysaccharides structures determination.

Keywords: Carbohydrates, Quantum chemistry, Collision-induced dissociation, Mass spectroscopy, Structural search