title: Defying entropy: forming large head-to-tail macrocycles in the gas phase.
abstract: Spectral fingerprints: Collision-induced dissociation (CID) of protonated peptides in the gas phase results in linear fragment ions with a five-membered oxazolone ring on their C-terminal side. Infrared spectroscopy confirms that smaller fragments adopt oxazolone structures. Conversely, in mid-sized and larger fragments an isomerization to "head-to-tail" macrocycles is observed (see picture).
authors.affiliation: Department of Chemistry, University of Florida, Buckman Drive, P.O. Box 117200, Gainesville, FL 32611, USA.
authors.forename: Marcus
authors.initials: M
authors.lastname: Tirado
authors.forename: Nicolas C
authors.initials: NC
authors.lastname: Polfer
mesh_terms: D019277:Entropy; D005740:Gases / Q000737:chemistry; D047028:Macrocyclic Compounds / Q000138:chemical synthesis*; D015394:Molecular Structure; D010455:Peptides / Q000138:chemical synthesis*
chemical_list: D005740:Gases; D047028:Macrocyclic Compounds; D010455:Peptides