Action Spectroscopy of Gas-Phase Peptide
Ions with Energetic Photons
11
Thomas Schlatho ¨ lter and Ronnie Hoekstra
Abstract
Photodissociation studies on free complex protonated peptides and other biomolecular ions have long been limited to the UV wavelength range and longer
wavelengths which are accessible by intense lasers. By interfacing tandem mass
spectrometry with synchrotron beamlines, it is possible to overcome this limitation. We have thoroughly studied the interaction of vacuum ultraviolet (VUV)
and soft X-ray photons with gas phase protonated peptides. Molecular fragmentation patterns, unobserved in conventional mass spectrometry, can be observed
experimentally. Instead of relatively slow statistical fragmentation along the
peptide backbone, much faster formation of fragment ions related to sidechains
of aromatic amino acids is observed. The underlying process most likely
involves fast charge migration. A previously unobserved dissociation scheme,
in which photoabsorption leads to a fast loss of a tyrosine side chain can be
observed for the VUV and soft X-ray range. This loss process leads to the
formation of a residual peptide that is remarkably cold internally.
11.1 Introduction
For many decades, optical spectroscopy approaches have been amongst the most
important experimental tools for the exploration of molecular structure and dynamics. The dynamics of complex (bio-)molecular systems lie at the very heart of
functionality in nature. The driving force of structural dynamics in biomolecular
systems are changes in the molecular electronic structure which subsequently
couple to atomic motion. For example, structural changes of biomolecular
complexes upon absorption of a visible-light photon are at the basis of natural
T. Schlatho ¨lter (*) • R. Hoekstra
Atomic and Molecular Physics Group, University of Groningen, Zernikelaan 25 9747AA
Groningen, The Netherlands
e-mail: tschlat@kvi.nl; r.a.hoekstra@rug.nl
S. Brøndsted Nielsen and J.A. Wyer (eds.), Photophysics of Ionic Biochromophores,
Physical Chemistry in Action, DOI 10.1007/978-3-642-40190-9_11,
# Springer-Verlag Berlin Heidelberg 2013
209
Ions with Energetic Photons
11
Thomas Schlatho ¨ lter and Ronnie Hoekstra
Abstract
Photodissociation studies on free complex protonated peptides and other biomolecular ions have long been limited to the UV wavelength range and longer
wavelengths which are accessible by intense lasers. By interfacing tandem mass
spectrometry with synchrotron beamlines, it is possible to overcome this limitation. We have thoroughly studied the interaction of vacuum ultraviolet (VUV)
and soft X-ray photons with gas phase protonated peptides. Molecular fragmentation patterns, unobserved in conventional mass spectrometry, can be observed
experimentally. Instead of relatively slow statistical fragmentation along the
peptide backbone, much faster formation of fragment ions related to sidechains
of aromatic amino acids is observed. The underlying process most likely
involves fast charge migration. A previously unobserved dissociation scheme,
in which photoabsorption leads to a fast loss of a tyrosine side chain can be
observed for the VUV and soft X-ray range. This loss process leads to the
formation of a residual peptide that is remarkably cold internally.
11.1 Introduction
For many decades, optical spectroscopy approaches have been amongst the most
important experimental tools for the exploration of molecular structure and dynamics. The dynamics of complex (bio-)molecular systems lie at the very heart of
functionality in nature. The driving force of structural dynamics in biomolecular
systems are changes in the molecular electronic structure which subsequently
couple to atomic motion. For example, structural changes of biomolecular
complexes upon absorption of a visible-light photon are at the basis of natural
T. Schlatho ¨lter (*) • R. Hoekstra
Atomic and Molecular Physics Group, University of Groningen, Zernikelaan 25 9747AA
Groningen, The Netherlands
e-mail: tschlat@kvi.nl; r.a.hoekstra@rug.nl
S. Brøndsted Nielsen and J.A. Wyer (eds.), Photophysics of Ionic Biochromophores,
Physical Chemistry in Action, DOI 10.1007/978-3-642-40190-9_11,
# Springer-Verlag Berlin Heidelberg 2013
209