title: Diagnostic NH and OH vibrations for oxazolone and diketopiperazine structures: b2 from protonated triglycine.
abstract: We present infrared multiple photon dissociation (IRMPD) spectra in the hydrogen stretching region of the simplest b fragment, b(2) 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, b(2) 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 NH(2) 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.
authors.affiliation: Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
authors.forename: Da
authors.initials: D
authors.lastname: Wang
authors.forename: Kerim
authors.initials: K
authors.lastname: Gulyuz
authors.forename: Corey N
authors.initials: CN
authors.lastname: Stedwell
authors.forename: Nick C
authors.initials: NC
authors.lastname: Polfer
mesh_terms: D054659:Diketopiperazines / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods*; D008968:Molecular Conformation; D009842:Oligopeptides / Q000737:chemistry*; D010081:Oxazolone / Q000737:chemistry*; D010879:Piperazines / Q000737:chemistry; D011522:Protons; D013055:Spectrophotometry, Infrared; D014732:Vibration
chemical_list: D054659:Diketopiperazines; D009842:Oligopeptides; D010879:Piperazines; D011522:Protons; D010081:Oxazolone; C010939:2,5-dioxopiperazine; C035647:glycyl-glycyl-glycine