Design and Synthesis of A Caged Zn2+ Probe, 8-Benzenesulfonyloxy-5-N,N-dimethylaminosulfonylquinolin-2-ylmethyl-pendant 1,4,7,10-Tetraazacyclododecane, and Its Hydrolytic Uncaging upon Complexation with Zn2+
journal contributionposted on 07.04.2008 by Shin Aoki, Kazusa Sakurama, Ryosuke Ohshima, Nanako Matsuo, Yasuyuki Yamada, Ryoko Takasawa, Sei-ichi Tanuma, Kei Takeda, Eiichi Kimura
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8-Benzenesulfonyloxy-5-N,N-dimethylaminosulfonylquinolin-2-ylmethyl-pendant cyclen (BS-caged-L4, BS = benzenesulfonyl) was designed and synthesized as a “caged” derivative of a previously described Zn2+ fluorophore, 8-hydroxy-5-N,N-dimethylaminosulfonylquinolin-2-ylmethyl-pendant cyclen (L4) (cyclen = 1,4,7,10-tetraazacyclododecane). In the absence of metal ions and in the dark, BS-caged-L4 (10 µM) showed negligible fluorescence emission at pH 7.4 (10 mM HEPES with I = 0.1 (NaNO3)) and 25 °C (excitation at 328 nm). Addition of Zn2+ induced an increase in the UV/vis absorption of BS-caged-L4 (10 µM) at 258 nm and a significant increase in fluorescence emission at 512 nm. These responses are results from the formation of Zn(H−1L4) by the hydrolysis of the sulfonyl ester at the 8-position of the quinoline unit promoted by the Zn2+-bound HO−. Improvement of cell membrane permeation in comparison with L4 is also described.