title: Ion mobility spectrometry, infrared dissociation spectroscopy, and ab initio computations toward structural characterization of the deprotonated leucine-enkephalin peptide anion in the gas phase.
abstract: Although the sequencing of protonated proteins and peptides with tandem mass spectrometry has blossomed into a powerful means of characterizing the proteome, much less effort has been directed at their deprotonated analogues, which can offer complementary sequence information. We present a unified approach to characterize the structure and intermolecular interactions present in the gas-phase pentapeptide leucine-enkephalin anion by several vibrational spectroscopy schemes as well as by ion-mobility spectrometry, all of which are analyzed with the help of quantum-chemical computations. The picture emerging from this study is that deprotonation takes place at the C terminus. In this configuration, the excess charge is stabilized by strong intramolecular hydrogen bonds to two backbone amide groups and thus provides a detailed picture of a potentially common charge accommodation motif in peptide anions.
authors.affiliation: Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT) , 76021 Karlsruhe, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Schinle
authors.forename: Christoph R
authors.initials: CR
authors.lastname: Jacob
authors.forename: Arron B
authors.initials: AB
authors.lastname: Wolk
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Greisch
authors.forename: Matthias
authors.initials: M
authors.lastname: Vonderach
authors.forename: Patrick
authors.initials: P
authors.lastname: Weis
authors.forename: Oliver
authors.initials: O
authors.lastname: Hampe
authors.forename: Mark A
authors.initials: MA
authors.lastname: Johnson
authors.forename: Manfred M
authors.initials: MM
authors.lastname: Kappes
mesh_terms: D004743:Enkephalin, Leucine / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D006860:Hydrogen Bonding; D013058:Mass Spectrometry; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D011522:Protons; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared
chemical_list: D005740:Gases; D010446:Peptide Fragments; D011522:Protons; D004743:Enkephalin, Leucine