C O M M U N I C A T I O N S
In conclusion, we developed novel luminogenic lanthanide probes
for detecting protease activities. The probe design principle could
be widely applicable to time-resolved assays for any proteases.
These lanthanide-based probes could accelerate drug-screening
processes and also contribute to the clarification of biological
systems. Furthermore, achievement of longer wavelength excitation
could enable a microscopic time-resolved fluorescence imaging of
protease activities in living cells.13
Acknowledgment. We thank MEXT of Japan and JST for the
financial supports. We thank Dr. Tomoyoshi Suenobu for the
technical support for time-resolved fluorescence measurement.
Figure 2. (a) Steady-state and (b) time-resolved (delay time, 10 µs; gate
time, 3.0 ms) emission spectral change of Suc-LY-Abd-Tb with calpain I.
λex ) 250 nm.
Table 1. Photophysical Properties of the Synthesized Compounds
Supporting Information Available: Detailed synthetic procedures;
supplementary spectra; physical properties; photostability experiment;
enzyme reaction experiment. This material is available free of charge
λ
abs/nm
ꢀ/M-1 cm-1
Φ
τ/ms
[1-Tb3+
[2-Tb3+
]
]
240
284
254
263
12 000
3 500
11 000
13 000
0.051 1.47
<0.001 1.49
<0.001 1.46
0.012 1.45
Suc-LY-Abd-Tb
Suc-LY-Abd-Tb + calpain Ia
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Finally, to demonstrate the generality of our sensing system, we
synthesized another lanthanide-based probe, Leu-Abd-Tb, for
leucine aminopeptidase (LAP); this enzyme hydrolyzes the peptide
bond of N-terminal hydrophobic amino acids such as leucine
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