Low temperature aqueous electrospray ionization mass spectrometry of noncovalent complexes

T. D. Veenstra, A. J. Tomlinson, L. Benson, R. Kumar, S. Naylor

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


In the present study we describe conditions that permit the characterization of noncovalent protein-substrate complexes in aqueous solution by microspray electrospray ionization-mass spectrometry (ESI-MS), using a heated transfer capillary at low temperature (45 °C). Specifically, we examined the binding of calmodulin to two polypeptides; the calmodulin-binding domain of calmodulin-dependent protein kinase II (CamK-II) and melittin. Calmodulin, a well known calcium-binding protein, binds to a number of small amphipathic peptides in a calcium-dependent manner. Our results directly show that both peptides form equimolar complexes with calmodulin only in the presence of calcium. The stoichiometry necessary for the formation of each complex was 1:1:4 for calmodulin:peptide (melittin or CamK-II):Ca2+, respectively. Furthermore, it is demonstrated that the detection of the complex in ESI-MS is source temperature dependent.

Original languageEnglish (US)
Pages (from-to)580-584
Number of pages5
JournalJournal of the American Society for Mass Spectrometry
Issue number6
StatePublished - 1998

ASJC Scopus subject areas

  • Structural Biology
  • Spectroscopy


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