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Synthesis of an azido-tagged low affinity ratiometric calcium sensor.

Caldwell ST, Cairns AG, Olson M, Chalmers S, Sandison M, Mullen W, McCarron JG, Hartley RC - Tetrahedron (2015)

Bottom Line: The synthesis of a dual excitation, ratiometric calcium ion sensor with a K d 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 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.

View Article: PubMed Central - PubMed

Affiliation: WestCHEM School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.

ABSTRACT

Changes in high localised concentrations of Ca(2+) ions are fundamental to cell signalling. The synthesis of a dual excitation, ratiometric calcium ion sensor with a K d 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.

No MeSH data available.


Related in: MedlinePlus

The design of NitroAzidoFuraRed.
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fig1: The design of NitroAzidoFuraRed.

Mentions: Given these excellent properties of Fura-Red, we decided to adjust its binding affinity so that it could detect changes when [Ca2+] is high. The binding dissociation constant (Kd) should be midway between the starting and final [Ca2+] in the process under study to maximise the observable response of the sensor. Most of the commonly-used Ca2+ sensors have Kd values within the nanomolar range (e.g., Fura-Red has a Kd=380 nM22, 25), which makes them suitable for measuring global cytosolic [Ca2+] fluxes.10, 11 We reasoned that a low affinity Fura-Red derivative, NitroAzidoFuraRed (Fig. 1), could be prepared that would have an azido tag for bioorthogonal chemistry.26


Synthesis of an azido-tagged low affinity ratiometric calcium sensor.

Caldwell ST, Cairns AG, Olson M, Chalmers S, Sandison M, Mullen W, McCarron JG, Hartley RC - Tetrahedron (2015)

The design of NitroAzidoFuraRed.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660056&req=5

fig1: The design of NitroAzidoFuraRed.
Mentions: Given these excellent properties of Fura-Red, we decided to adjust its binding affinity so that it could detect changes when [Ca2+] is high. The binding dissociation constant (Kd) should be midway between the starting and final [Ca2+] in the process under study to maximise the observable response of the sensor. Most of the commonly-used Ca2+ sensors have Kd values within the nanomolar range (e.g., Fura-Red has a Kd=380 nM22, 25), which makes them suitable for measuring global cytosolic [Ca2+] fluxes.10, 11 We reasoned that a low affinity Fura-Red derivative, NitroAzidoFuraRed (Fig. 1), could be prepared that would have an azido tag for bioorthogonal chemistry.26

Bottom Line: The synthesis of a dual excitation, ratiometric calcium ion sensor with a K d 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 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.

View Article: PubMed Central - PubMed

Affiliation: WestCHEM School of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.

ABSTRACT

Changes in high localised concentrations of Ca(2+) ions are fundamental to cell signalling. The synthesis of a dual excitation, ratiometric calcium ion sensor with a K d 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.

No MeSH data available.


Related in: MedlinePlus