Protein-Metal Interactions of Calmodulin and alpha-Synuclein Monitored by Selective Noncovalent Adduct Protein Probing Mass Spectrometry

Tony Ly, Ryan R. Julian

    Research output: Contribution to journalArticlepeer-review

    44 Citations (Scopus)


    The metal binding properties of proteins are biologically significant, particularly in relationship to the molecular origins of disease and the discovery of therapeutic pharmaceutical treatments. Herein, we demonstrate that selective noncovalent adduct protein probing mass spectrometry (SNAPP-MS) is a sensitive technique to investigate the structural effects of protein-metal interactions. We utilize specific, noncovalent interactions between 18-crown-6 ether (18C6) and lysine to probe protein structure in the presence and absence of metal ions. Application of SNAPP-MS to the calmodulin-Ca2+ system demonstrates that changes in protein structure are reflected in a substantial change in the number and intensity of 18C6s, which bind to the protein as observed by MS. In this manner, SNAPP is demonstrated to be a sensitive technique for monitoring ligand-induced conformational rearrangements in proteins. In addition, SNAPP is well-suited to examine the properties of natively unfolded proteins, where structural changes are more difficult to detect by other methods. For example, α-synuclein is a protein associated in the pathology of Parkinson’s disease, which is known to aggregate more rapidly in the presence of Al3+ and Cu2+. The 18C6 SNAPP distributions for α-synuclein change dramatically in the presence of 3 µM Al3+, revealing that Al3+ binding causes a significant change in the conformational dynamics of the monomeric form of this disordered protein. In contrast, binding of Cu2+ does not induce a significant shift in 18C6 binding, suggesting that noteworthy structural reorganizations at the monomeric level are minimal. These results are consistent with the idea that the metal-induced aggregation caused by Al3+ and Cu2+ proceed by independent pathways.
    Original languageEnglish
    Pages (from-to)1663-1672
    Number of pages10
    JournalJournal of The American Society for Mass Spectrometry
    Issue number11
    Publication statusPublished - Nov 2008


    • Charge State
    • 18C6
    • Zebra Finch
    • SNAPP Distribution
    • 18C6 Binding


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