Synthesis of an azido-tagged low affinity ratiometric calcium sensor

Stuart T. Caldwell, Andrew G. Cairns, Marnie Olson, Susan Chalmers, Mairi Sandison, William Mullen, John G. McCarron, Richard C. Hartley (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
36 Downloads (Pure)


Changes in high localised concentrations of Ca2+ ions are fundamental to cell signalling. The synthesis of a dual excitation, ratiometric calcium ion sensor with a Kd of 90 μM, is described. It is tagged with an azido group for bioconjugation, and absorbs in the blue/green and emits in the red region of the visible spectrum with a large Stokes shift. The binding modulating nitro group is introduced to the BAPTA core prior to construction of a benzofuran-2-yl carboxaldehyde by an allylation-oxidation-cyclisation sequence, which is followed by condensation with an azido-tagged thiohydantoin. The thiohydantoin unit has to be protected with an acetoxymethyl (AM) caging group to allow CuAAC click reaction and incorporation of the KDEL peptide endoplasmic reticulum (ER) retention sequence.

Original languageEnglish
Pages (from-to)9571-9578
Number of pages8
Issue number51
Early online date20 Oct 2015
Publication statusPublished - 23 Dec 2015


  • Bioorthogonal
  • Calcium
  • Fluorescence
  • Thiohydantoin

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry


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