Protein Dimerization on a Phosphonated Calix[6]arene Disc

Martin Rennie, Aishling Doolan, Colin Raston, Peter Crowley, Peter Crowley

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    49 Citations (Scopus)


    Complex formation between cationic cytochrome c and the water-soluble, poly-anionic p-phosphonatocalix[6]arene (pclx6) was investigated. A crystal structure (at 1.8 Å resolution) revealed a remarkable dimeric disc of pclx6 that acts like glue to mediate a symmetric (C2) protein dimer. The calixarene disc has a diameter of about 1.5 nm and masks about 360 Å2 of protein surface. The key protein–calixarene contacts occur via two linchpin lysines, with additional contacts provided by a small hydrophobic patch. The protein–calixarene supramolecular assemblies were observed in solution by size-exclusion chromatography with multi-angle light scattering and NMR spectroscopy. Using isothermal titration calorimetry and NMR data, an apparent Kd in the low micromolar range was determined for the charge-rich protein–calixarene complex. In contrast to p-sulfonatocalix[4]arene, the larger pclx6 has a single, well-defined binding site that mediates the assembly of cytochrome c in solution.

    Original languageEnglish
    Pages (from-to)5517-5521
    Number of pages5
    JournalAngewandte Chemie-International Edition
    Issue number20
    Publication statusPublished - 8 May 2017


    • cytochrome c
    • lysine recognition
    • polyanions
    • self-assembly
    • structure elucidation


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