title: Covalent adducts of melphalan with free amino acids and a model peptide studied by liquid chromatography/tandem mass spectrometry.
abstract: BACKGROUND
  Melphalan is a frequently used chemotherapeutical agent for the treatment of myeloma, breast cancer, ovarian cancer and sarcoma of soft tissue. A good knowledge of the reactivity of the drug toward the different amino acids, e.g. covalent adduct formation, is crucial for the understanding of its activity and side effects during cancer treatment.
  
  
  METHODS
  The reactivity of melphalan and sites of adduct formation were studied by in vitro incubation of melphalan with free amino acids and glutathione as a model peptide. The formed covalent adducts were investigated using ultra-performance liquid chromatography tandem mass spectrometry (UPLC/MS/MS) using a triple-quadrupole instrument. Accurate mass measurements for the confirmation of characteristic product ions were performed on a quadrupole time-of-flight (QTOF) mass spectrometer.
  
  
  RESULTS
  The incubation of melphalan with different classes of amino acids resulted in the formation of adducts on the amino and carboxyl termini, as well as adduct formation in the reactive side chains of Cys, Met, Tyr, His, Lys, Asp and Glu. All these melphalan adducts could be identified by their characteristic collision-induced dissociation (CID) product ion patterns.
  
  
  CONCLUSIONS
  The present study demonstrates the reactivity of melphalan towards the functional groups of amino acids. The different alkylation site products show distinctive fragmentation patterns, which enable a fast identification of the different melphalan adducts. This study is a first important step towards a better understanding of the adduct formation in more complex molecules, e.g. peptides and proteins.
authors: Department of Chemistry, Biomolecular and Analytical Mass Spectrometry, University of Antwerp, Antwerp, Belgium.
authors: Debbie
authors: D
authors: Dewaele
authors: Department of Chemistry, Biomolecular and Analytical Mass Spectrometry, University of Antwerp, Antwerp, Belgium.|Center for Proteomics (CFP-CeProMa), University of Antwerp, Antwerp, Belgium.
authors: Frank
authors: F
authors: Sobott
authors: Department of Chemistry, Biomolecular and Analytical Mass Spectrometry, University of Antwerp, Antwerp, Belgium.|Center for Proteomics (CFP-CeProMa), University of Antwerp, Antwerp, Belgium.
authors: Filip
authors: F
authors: Lemière
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D018736:DNA Adducts / Q000737:chemistry*; D008558:Melphalan / Q000737:chemistry*; D008956:Models, Chemical; D010455:Peptides / Q000032:analysis / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000596:Amino Acids; D018736:DNA Adducts; D010455:Peptides; D008558:Melphalan