IR Spectroscopy of b4 Fragment Ions of Protonated Pentapeptides in the X-H (X=C,N,O) Region

SYLVÈRE DURAND; MAXIMILIANO ROSSA; OSCAR HERNANDEZ; BÉLA PAIZS; PHILIPPE MAÎTRE

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 vol. 117 p. 2508 - 2508

he structure of peptide fragments was studied using ‘action’ IR spectroscopy. We report on room temperature IR spectra of b4 fragments of protonated GGGGG, AAAAA, and YGGFL in the X-H (X=C, N, O) stretching region. Experiments were performed with a Tandem mass spectrometer combined with table top tunable laser, and the multiple photon absorption process was assisted using an auxiliary high power CO2 laser. These experiments provided well-resolved spectra with relatively narrow peaks in the X-H (X=C, N, O) stretching region for the b4 fragments of protonated GGGGG, AAAAA, and YGGFL. The 3200-3700 cm-1rangeof the first two of these spectra are rather similar, and the corresponding peaks can be assigned based on the classical b ion structure that has a linear backbone terminated by the oxazolone ring at the C-terminus and ionizing proton residing on the oxazolone ring nitrogen. The spectrum of the b4 of YGGFL, on the other hand, is different from the two others, and is characterized by a