Spectroscopic evidence for an oxazolone structure of the b(2) fragment ion from protonated tri-alanine.
Infrared multiple photon dissociation (IRMPD) spectroscopy is used to identify the structure of the b(2)(+) ion generated from protonated tri-alanine by collision induced dissociation (CID). The IRMPD spectrum of b(2)(+) differs markedly from that of protonated cyclo-alanine-alanine, demonstrating that the product is not a diketopiperazine. Instead, comparison of the IRMPD spectrum of b(2)(+) to spectra predicted by density functional theory provides compelling evidence for an oxazolone structure protonated at the oxazolone N-atom.
Oomens
Jos
J
FOM Institute for Plasma Physics Rijnhuizen, Nieuwegein, The Netherlands. joso@rijnhuizen.nl
Young
Sarah
S
Molesworth
Sam
S
van Stipdonk
Michael
M
D009842:Oligopeptides / Q000737:chemistry*; D010081:Oxazolone / Q000737:chemistry*; D011522:Protons; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared / Q000379:methods*
D009842:Oligopeptides; D011522:Protons; D010081:Oxazolone; C039944:alanyl-alanyl-alanine