Unknown

Dataset Information

0

Spectroscopic Evidence for Lactam Formation in Terminal Ornithine b2+ and b3+ Fragment Ions.


ABSTRACT: Infrared multiple photon dissociation action spectroscopy was performed on the AlaOrn b2+ and AlaAlaOrn b3+ fragment ions from ornithine-containing tetrapeptides. Infrared spectra were obtained in the fingerprint region (1000-2000 cm-1) using the infrared free electron lasers at the Centre Laser Infrarouge d'Orsay (CLIO) facility in Orsay, France, and the free electron lasers for infrared experiments (FELIX) facility in Nijmegen, the Netherlands. A novel terminal ornithine lactam AO+ b2+ structure was synthesized for experimental comparison and spectroscopy confirms that the b2+ fragment ion from AOAA forms a lactam structure. Comparison of experimental spectra with scaled harmonic frequencies at the B3LYP/6-31+G(d,p) level of theory shows that AO+ b2+ forms a terminal lactam protonated either on the lactam carbonyl oxygen or the N-terminal nitrogen atom. Several low-lying conformers of these isomers are likely populated following IRMPD dissociation. Similarly, a comparison of the experimental IRMPD spectrum with calculated spectra shows that AAO+ b3+-ions also adopt a lactam structure, again with multiple different protonation sites, during fragmentation. This study provides spectroscopic confirmation for the lactam cyclization proposed for the "ornithine effect" and represents an alternative bn+ structure to the oxazolone and diketopiperazine/macrocycle structures most often formed.

SUBMITTER: Smith ZM 

PROVIDER: S-EPMC6697629 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

altmetric image

Publications

Spectroscopic Evidence for Lactam Formation in Terminal Ornithine b<sub>2</sub><sup>+</sup> and b<sub>3</sub><sup>+</sup> Fragment Ions.

Smith Zachary M ZM   Wang Xiye X   Scheerer Jonathan R JR   Martens Jonathan J   Berden Giel G   Oomens Jos J   Steinmetz Vincent V   Somogyi Arpad A   Wysocki Vicki V   Poutsma John C JC  

Journal of the American Society for Mass Spectrometry 20190610 9


Infrared multiple photon dissociation action spectroscopy was performed on the AlaOrn b<sub>2</sub><sup>+</sup> and AlaAlaOrn b<sub>3</sub><sup>+</sup> fragment ions from ornithine-containing tetrapeptides. Infrared spectra were obtained in the fingerprint region (1000-2000 cm<sup>-1</sup>) using the infrared free electron lasers at the Centre Laser Infrarouge d'Orsay (CLIO) facility in Orsay, France, and the free electron lasers for infrared experiments (FELIX) facility in Nijmegen, the Netherl  ...[more]

Similar Datasets

| S-EPMC3647700 | biostudies-literature
| S-EPMC3641857 | biostudies-literature
| S-EPMC6267623 | biostudies-literature
| S-EPMC3325924 | biostudies-other
| S-EPMC7199424 | biostudies-literature
| S-EPMC3305447 | biostudies-literature