Gas-phase formation of large neutral alkaline-earth metal tryptophan complexes


We report on the first observation of isolated large neutral metal amino acid complexes such as Trp n Me k , with Me = Ca, Ba, Sr, cluster combinations covering n = 1–33, k = 0..2 and masses beyond 6500 u. The cluster beam is generated using UV laser desorption from a mixed powder of alkaline-earth metal salts and tryptophan inside a cluster mixing channel. The particles are detected using VUV photoionization followed by time-of-flight mass spectroscopy. The enhanced stability of metal amino acid clusters over pure amino acid clusters is substantiated in molecular dynamics simulations by determining the gain in binding energy related to the inclusion of the metal atoms.


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Correspondence to Markus Arndt.

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Published online April 26, 2008

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Marksteiner, M., Haslinger, P., Ulbricht, H. et al. Gas-phase formation of large neutral alkaline-earth metal tryptophan complexes. J Am Soc Mass Spectrom 19, 1021–1026 (2008).

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  • Cluster Size Distribution
  • Calcium Atom
  • CHARMM Force Field
  • Amino Acid Cluster
  • Tryptophan Molecule