Ionic selectivity of low-affinity ratiometric calcium indicators: mag-Fura-2, Fura-2FF and BTC
Ionic selectivity of low-affinity ratiometric calcium indicators: mag-Fura-2, Fura-2FF and BTC
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DOI：
10.1054/ceca.1999.0092
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发表时间：
2000-02-01
期刊：
影响因子：
4
通讯作者：
Goldberg, MP
中科院分区：
文献类型：
--
作者：
Hyrc, KB;Bownik, JM;Goldberg, MP
准确测量升高的细胞内钙水平需要具有低钙亲和力和高选择性的指示剂。我们研究了三个低亲和力的荧光光谱特性和离子特异性，比例指示剂结构相关的Fura-2：mag-fura-2（furaptra），Fura-2FF和BTC。这些指示剂在激发波长、对Ca 2+的亲和力（Kd分别类似于20 μ M、6 μ M和12 μ M）和对Mg 2（+）的选择性（对于mag-fura-2，Kd类似于2 mM，对于Fura-2FF和ETC，Kd>10 mM）方面不同。在测试的指标中，BTC受到Ca 2+结合后的适度动态范围、对光损伤的敏感性和对pH值变化的敏感性的限制。所有三个指标结合其他金属离子，包括Zn 2+、Cd 2+和Gd 3+。有趣的是，只有在BTC的情况下，Ca 2+和其他金属离子之间的光谱差异是明显的。例如，在Ca 2+等吸光点处，Zn 2+的存在使BTC荧光增加6倍，表明该染料可用作荧光Zn 2+指示剂。Fura-2FF具有高特异性、宽动态范围和低pH敏感性，是大多数成像应用的最佳低亲和力Ca 2+指示剂。如果实验条件需要可见波长激发或对包括Zn 2+的其他金属离子敏感，则BTC可能是有用的。(C)2000年哈考特出版社有限公司
Accurate measurement of elevated intracellular calcium levels requires indicators with low calcium affinity and high selectivity. We examined fluorescence spectral properties and ionic specificity of three low-affinity, ratiometric indicators structurally related to Fura-2: mag-fura-2 (furaptra), Fura-2FF, and BTC. The indicators differed in respect to their excitation wavelengths, affinity for Ca2+ (K-d similar to 20 mu M, 6 mu M and 12 mu M respectively) and selectivity over Mg2(+) (K-d similar to 2 mM for mag-fura-2, >10 mM for Fura-2FF and ETC). Among the tested indicators, BTC was limited by a modest dynamic range upon Ca2+ binding, susceptibility to photodamage, and sensitivity to alterations in pH. All three indicators bound other metal ions including Zn2+, Cd2+ and Gd3+. Interestingly, only in the case of BTC were spectral differences apparent between Ca2+ and other metal ions. For example, the presence of Zn2+ increased BTC fluorescence 6-fold at the Ca2+ isosbestic point, suggesting that this dye may be used as a fluorescent Zn2+ indicator. Fura-2FF has high specificity, wide dynamic range, and low pH sensitivity, and is an optimal low-affinity Ca2+ indicator for most imaging applications. BTC may be useful if experimental conditions require visible wavelength excitation or sensitivity to other metal ions including Zn2+. (C) 2000 Harcourt Publishers Ltd.