Observation of pronounced b*,y cleavages in the electron capture dissociation mass spectrometry of polyamidoamine (PAMAM) dendrimer ions with amide functionalities.
We report the electron capture dissociation (ECD) mass spectrometry of the third generation polyamidoamine (PAMAM) dendrimer that contains amide functionalities. The dendrimer was chosen because it offers a unique opportunity to understand the ECD behavior of the amide functionality in a framework other than peptides/proteins. In this study, PAMAM ECD was found to exhibit a fragmentation pattern strikingly different from that of ordinary peptide/protein ECD. Specifically, ECD of multiply protonated PAMAM ions gave rise to significant b(*),y cleavages as well as S,E dissociations but, unexpectedly, only minor c,z(*) fragmentations are observed. In an effort to account for the unexpectedly different fragmentation pattern, a comparative ECD experiment on the poly(propylene imine) dendrimer in which the amide bond moiety is not available and density functional theory calculations (B3LYP/6-311 + G(d)) investigations on the model system of a charge-solvated single-repeat unit were carried out. On the basis of these results, we discuss here possible implications of intramolecular charge-solvation, energy barriers in dissociation reactions, and macromolecular properties of the dendritic molecule for understanding the reaction pathway of PAMAM ECD.
Lee
Sunyoung
S
Department of Chemistry and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Sinsudong 1, 121-742, Mapogu, Seoul, Republic of Korea.
Han
Sang Yun
SY
Division of Chemical Metrology and Materials Evaluation, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea.
Lee
Tae Geol
TG
Division of Chemical Metrology and Materials Evaluation, Korea Research Institute of Standards and Science, Daejeon, Republic of Korea.
Chung
Gyusung
G
Department of Chemistry, Konyang University, Chungnam, Republic of Korea.
Lee
Duckhwan
D
Department of Chemistry and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Sinsudong 1, 121-742, Mapogu, Seoul, Republic of Korea.
Oh
Han Bin
HB
Department of Chemistry and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Sinsudong 1, 121-742, Mapogu, Seoul, Republic of Korea. hanbinoh@sogang.ac.kr.