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Optical Control of Calcium Affinity in a Spiroamido-rhodamine Based Calcium Chelator

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journal contribution
posted on 15.04.2011, 00:00 by Liangxing Wu, Yingrui Dai, Gerard Marriott
An optically controlled Ca2+-chelator 1 was developed to mimic natural calcium oscillations. Compound 1, a spiroamido-rhodamine derivative of 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA), underwent cycles of reversible transitions between a colorless closed state and a fluorescent open form. The closed-state exhibited a high affinity for Ca2+ (Kd: 509 nM) with excellent selectivity over Mg2+ (Kd: 19 mM). The open isomer had a 350-fold lower Ca2+ affinity (Kd: 181 μM), while the Mg2+ affinity was not significantly affected (Kd: 14 mM).