QUIN 2，四钾盐

已证明QUIN 2，四钾盐是Zn | 2+ |-蛋白复合物的指标。Ca| 2+ |与QUIN2的结合导致UV吸收光谱发生重大变化，荧光增强20倍量子产率。TPEN可与QUIN 2结合使用，以减少细胞中QUIN 2荧光的重金属淬灭。在低钙浓度（例如354 nm，em。510 nm）存在下的光谱特性不同于在高钙条件下（例如332 nm，em。505 nm）的光谱特性。

QUIN 2, Tetrapotassium Salt has been demonstrated to be an indicator of Zn|2+|-protein complexes.The binding of Ca|2+|to QUIN 2 leads to a major shift in UV absorption spectrum and a twenty-fold enhancement in fluorescence quantum yield. TPEN can be used in conjunction with QUIN 2 to reduce heavy-metal quenching of QUIN 2 fluorescence in cells. Spectral properties in the presence of low calcium concentrations (ex. 354 nm, em. 510 nm) differ from those during high calcium conditions (ex. 332 nm, em. 505 nm).