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@ARTICLE{Pattky:276452,
      author       = {Pattky, Martin and Nicolardi, Simone and Santiago-Schübel,
                      Beatrix and Sydes, Daniel and van der Burgt, Yuri E. M. and
                      Klein, Antonia N. and Jiang, Nan and Mohrlüder, Jeannine
                      and Hänel, Karen and Kutzsche, Janine and Funke, S. A. and
                      Willbold, D. and Willbold, S. and Huhn, C.},
      title        = {{S}tructure characterization of unexpected covalent
                      {O}-sulfonation and ion-pairing on an extremely hydrophilic
                      peptide with {CE}-{MS} and {FT}-{ICR}-{MS}},
      journal      = {Analytical and bioanalytical chemistry},
      volume       = {407},
      number       = {22},
      issn         = {0016-1152},
      address      = {Berlin},
      publisher    = {Springer},
      reportid     = {FZJ-2015-06891},
      pages        = {6637 - 6655},
      year         = {2015},
      abstract     = {In this study, we characterized unexpected side-products in
                      a commercially synthesized peptide with the sequence
                      RPRTRLHTHRNR. This so-called peptide D3 was selected by
                      mirror phage display against low molecular weight
                      amyloid-β-peptide (Aβ) associated with Alzheimer’s
                      disease. Capillary electrophoresis (CE) was the method of
                      choice for structure analysis because the extreme
                      hydrophilicity of the peptide did not allow reversed-phase
                      liquid chromatography (RPLC) and hydrophilic interaction
                      stationary phases (HILIC). CE-MS analysis, applying a
                      strongly acidic background electrolyte and different
                      statically adsorbed capillary coatings, provided fast and
                      efficient analysis and revealed that D3 unexpectedly showed
                      strong ion-pairing with sulfuric acid. Moreover, covalent
                      O-sulfonation at one or two threonine residues was
                      identified as a result of a side reaction during peptide
                      synthesis, and deamidation was found at either the
                      asparagine residue or at the C-terminus. In total, more than
                      10 different species with different m/z values were
                      observed. Tandem-MS analysis with collision induced
                      dissociation (CID) using a CE-quadrupole-time-of-flight
                      (QTOF) setup predominantly resulted in sulfate losses and
                      did not yield any further characteristic fragment ions at
                      high collision energies. Therefore, direct infusion Fourier
                      transform ion cyclotron resonance (FT-ICR) MS was employed
                      to identify the covalent modification and discriminate
                      O-sulfonation from possible O-phosphorylation by using an
                      accurate mass analysis. Electron transfer dissociation (ETD)
                      was used for the identification of the threonine O-sulfation
                      sites. In this work, it is shown that the combination of
                      CE-MS and FT-ICR-MS with ETD fragmentation was essential for
                      the full characterization of this extremely basic peptide
                      with labile modifications.},
      cin          = {ICS-6},
      ddc          = {540},
      cid          = {I:(DE-Juel1)ICS-6-20110106},
      pnm          = {551 - Functional Macromolecules and Complexes (POF3-551)},
      pid          = {G:(DE-HGF)POF3-551},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000360220800009},
      pubmed       = {pmid:26123437},
      doi          = {10.1007/s00216-015-8826-8},
      url          = {https://juser.fz-juelich.de/record/276452},
}