Diagnostic NH and OH Vibrations for Oxazolone and Diketopiperazine Structures: b^sub 2^ from Protonated Triglycine

We present infrared multiple photon dissociation (IRMPD) spectra in the hydrogen stretching region of the simplest b fragment, b2 from protonated triglycine, contrasted to that of protonated cyclo(Gly-Gly). Both spectra confirm the presence of intense, diagnostic vibrations linked to the site of pro...

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Bibliographic Details
Published in:Journal of the American Society for Mass Spectrometry 2011-07, Vol.22 (7), p.1197
Main Authors: Wang, Da, Gulyuz, Kerim, Stedwell, Corey N, Polfer, Nick C
Format: Article
Language:English
Subjects:
Carbonyls
Diagnostic systems
Ions
Mass spectrometry
Peptides
Stretching
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Summary:We present infrared multiple photon dissociation (IRMPD) spectra in the hydrogen stretching region of the simplest b fragment, b2 from protonated triglycine, contrasted to that of protonated cyclo(Gly-Gly). Both spectra confirm the presence of intense, diagnostic vibrations linked to the site of proton attachment. Protonated cyclo(Gly-Gly) serves as a reference spectrum for the diketopiperazine structure, showing a diagnostic O-H+ stretch of the protonated carbonyl group at 3585 cm–1. Conversely, b2 from protonated triglycine exhibits a strong band at 3345 cm–1, associated with the N-H stretching mode of the protonated oxazolone ring structure. Other weaker N-H stretches can also be discerned, such as the amino NH2 and amide NH bands. These results demonstrate the usefulness of the hydrogen stretching region, and hence benchtop optical parametric oscillator/amplifier (OPO/A) set-ups, in making structural assignments of product ions in collision-induced dissociation (CID) of peptides.
ISSN:1044-0305
1879-1123
DOI:10.1007/s13361-011-0147-3