Table 1.
Spectroscopic Properties of Ditopic ZPP1 Derivatives
| Absorption maximuma λ (nm), ε×103 (M−1cm−1) |
Excitation maximuma λ (nm) |
Emission maximuma λ (nm), Φb |
Fluorescence pKac | ||||
|---|---|---|---|---|---|---|---|
| unbound | Zn(II)-saturated | unbound | Zn(II)-saturated | unbound | Zn(II)-saturated | ||
| ZPP1 | 517, 75(5) | 505, 82(2) | 505 | 505 | 532, 0.052d | 523, 0.70d | 6.24(1)e |
| ZPP1(6-CO2H) | 519, 77(3) | 505, 84(3) | 507 | 505 | 534, 0.0452(5) | 525, 0.67(2) | 6.21(1) |
| ZPP1(6-CO2Et) | 522, 74(2) | 508, 81(2) | 515 | 508 | 535, 0.031(5) | 528, 0.60(2) | 6.04(1) |
a
Measurements performed in aqueous buffer at pH 7.0, 50 mM PIPES, 100 mM KCl.
b
Fluorescein (Φ=0.95 in 0.1 M NaOH)35 was used as standard for quantum yield determinations.
c
pKa associated with the fluorescence increase going from high to low pH.
d
From reference 15.
e
Value as determined in the present work. Numbers in parentheses represent standard deviations in the last significant digit.