Abstract
The fragmentation reactions of isomeric dipeptides containing α- and β-alanine residues (αAla-αAla, αAla-βAla, βAla-αAla, and βAla-βAla) were studied using a combination of low-energy and energy resolved collision induced dissociation (CID). Each dipeptide gave a series of different fragment ions, allowing for differentiation. For example, peptides containing an N-terminal β-Ala residue yield a diagnostic imine loss, while lactam ions at m/z 72 are unique to peptides containing β-Ala residues. In addition, MS3 experiments were performed. Structure-specific fragmentation reactions were observed for y1 ions, which help identify the C-terminal residue. The MS3 spectra of the b2 ions are different suggesting they are unique for each peptide. Density functional theory (DFT) calculations predict that b2 ions formed via a neighboring group attack by the amide are thermodynamically favored over those formed via neighboring group attack by the N-terminal amine. Finally, to gain further insight into the unique fragmentation chemistry of the peptides containing an N-terminal β-alanine residue, the fragmentation reactions of protonated β-Ala-NHMe were examined using a combination of experiment and DFT calculations. The relative transition-state energies involved in the four competing losses (NH3, H2O, CH3NH2, and CH2=NH) closely follow the relative abundances of these as determined via CID experiments.
| Original language | English |
|---|---|
| Pages (from-to) | 1743-1754 |
| Number of pages | 12 |
| Journal | Journal of the American Society for Mass Spectrometry |
| Volume | 19 |
| Issue number | 12 |
| DOIs | |
| Publication status | Published - Dec 2008 |
Cite this
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Can α- and β-Alanine Containing Peptides Be Distinguished Based on the CID Spectra of Their Protonated Ions? / Lam, A. K Y; Ramarathinam, Sri H.; Purcell, Anthony W.; O'Hair, R. A J.
In: Journal of the American Society for Mass Spectrometry, Vol. 19, No. 12, 12.2008, p. 1743-1754.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - Can α- and β-Alanine Containing Peptides Be Distinguished Based on the CID Spectra of Their Protonated Ions?
AU - Lam, A. K Y
AU - Ramarathinam, Sri H.
AU - Purcell, Anthony W.
AU - O'Hair, R. A J
PY - 2008/12
Y1 - 2008/12
N2 - The fragmentation reactions of isomeric dipeptides containing α- and β-alanine residues (αAla-αAla, αAla-βAla, βAla-αAla, and βAla-βAla) were studied using a combination of low-energy and energy resolved collision induced dissociation (CID). Each dipeptide gave a series of different fragment ions, allowing for differentiation. For example, peptides containing an N-terminal β-Ala residue yield a diagnostic imine loss, while lactam ions at m/z 72 are unique to peptides containing β-Ala residues. In addition, MS3 experiments were performed. Structure-specific fragmentation reactions were observed for y1 ions, which help identify the C-terminal residue. The MS3 spectra of the b2 ions are different suggesting they are unique for each peptide. Density functional theory (DFT) calculations predict that b2 ions formed via a neighboring group attack by the amide are thermodynamically favored over those formed via neighboring group attack by the N-terminal amine. Finally, to gain further insight into the unique fragmentation chemistry of the peptides containing an N-terminal β-alanine residue, the fragmentation reactions of protonated β-Ala-NHMe were examined using a combination of experiment and DFT calculations. The relative transition-state energies involved in the four competing losses (NH3, H2O, CH3NH2, and CH2=NH) closely follow the relative abundances of these as determined via CID experiments.
AB - The fragmentation reactions of isomeric dipeptides containing α- and β-alanine residues (αAla-αAla, αAla-βAla, βAla-αAla, and βAla-βAla) were studied using a combination of low-energy and energy resolved collision induced dissociation (CID). Each dipeptide gave a series of different fragment ions, allowing for differentiation. For example, peptides containing an N-terminal β-Ala residue yield a diagnostic imine loss, while lactam ions at m/z 72 are unique to peptides containing β-Ala residues. In addition, MS3 experiments were performed. Structure-specific fragmentation reactions were observed for y1 ions, which help identify the C-terminal residue. The MS3 spectra of the b2 ions are different suggesting they are unique for each peptide. Density functional theory (DFT) calculations predict that b2 ions formed via a neighboring group attack by the amide are thermodynamically favored over those formed via neighboring group attack by the N-terminal amine. Finally, to gain further insight into the unique fragmentation chemistry of the peptides containing an N-terminal β-alanine residue, the fragmentation reactions of protonated β-Ala-NHMe were examined using a combination of experiment and DFT calculations. The relative transition-state energies involved in the four competing losses (NH3, H2O, CH3NH2, and CH2=NH) closely follow the relative abundances of these as determined via CID experiments.
UR - http://www.scopus.com/inward/record.url?scp=56949083494&partnerID=8YFLogxK
U2 - 10.1016/j.jasms.2008.09.007
DO - 10.1016/j.jasms.2008.09.007
M3 - Article
VL - 19
SP - 1743
EP - 1754
JO - Journal of the American Society for Mass Spectrometry
JF - Journal of the American Society for Mass Spectrometry
SN - 1044-0305
IS - 12
ER -