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Nat Chem. 2009 Oct;1(7):573-7. doi: 10.1038/nchem.352. Epub 2009 Aug 30.

Highly dynamic motion of crown ethers along oligolysine peptide chains.

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1
Institut für Chemie und Biochemie der Freien Universität, Berlin, Germany.

Erratum in

  • Nat Chem. 2009 Nov;1(8):668.

Abstract

Molecular mobility has attracted considerable attention in supramolecular chemistry and biochemistry, but the simple question of whether a small molecule can move directly between different binding sites of a multitopic host without intermediate dissociation has not been addressed so far. To study such processes, we consider hydrogen/deuterium exchange experiments on a model system comprising complexes formed between 18-crown-6 and oligolysine peptides. Because direct binding-site hopping is indistinguishable in solution from a dissociation/reassociation mechanism, here we show that the high vacuum of a mass spectrometer offers a unique environment for probing such processes. The highly dynamic motion of crown ethers along oligolysine peptide chains proceeds mechanistically by a simultaneous transfer of the crown ether from its ammonium ion binding site to a nearby amino group together with a proton. Furthermore, the exchange experiments unambiguously reveal the zwitterionic structure of the 18-crown-6/oligolysine complexes, highlighting the versatility and potential of gas-phase experiments for investigating non-covalent interactions.

PMID:
21378938
DOI:
10.1038/nchem.352
[Indexed for MEDLINE]
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