CALCIUM-BINDING TO FLUORESCENT CALCIUM INDICATORS - CALCIUM GREEN, CALCIUM ORANGE AND CALCIUM CRIMSON
CALCIUM-BINDING TO FLUORESCENT CALCIUM INDICATORS - CALCIUM GREEN, CALCIUM ORANGE AND CALCIUM CRIMSON
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DOI：
10.1016/s0006-291x(05)81278-1
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发表时间：
1991-10-15
影响因子：
3.1
通讯作者：
ERNE, P
中科院分区：
文献类型：
--
作者：
EBERHARD, M;ERNE, P
最近推出的荧光钙敏感指示器钙绿、钙橙和钙红表明了在低指示剂浓度下检测微小钙瞬变的重要改进和优势。用荧光滴定和停流荧光法分别测定了钙绿、钙橙和钙红的热力学离解常数和离解速率常数。钙与指示剂的结合符合1：1的钙：指示剂络合物，尽管在高浓度钙时，荧光性质与简单模型预测的行为略有偏离。在所考察的所有条件下，钙指示剂复合体的解离都是单指的。三种指示剂对钙的亲和力一般随温度升高(Kdat 11.5°C和39.7°C(NM)：钙绿261,180；钙橙527,323；钙深红色201,204)和pH(Kdat pH 6.42和7.40(NM)：314,226；钙橙562,457；钙深红色571,269)而增加。热力学离解常数的变化主要是由缔合速率常数的变化引起的。钙与指示剂结合的温度依赖性表明，这一过程在常温下是最有利的。
The recently introduced fluorescent calcium sensitive indicators calcium green, calcium orange and calcium crimson suggest important improvements and advantages to detect small calcium transients at low indicator concentrations. Thermodynamic dissociation constants and dissociation rate constants of calcium green, calcium orange and calcium crimson were measured by use of fluorescence titration and stopped flow fluorescence, respectively. Calcium binding to the indicators conforms to a 1:1 calcium: indicator complex although at high concentrations of calcium the fluorescence properties deviate somewhat from the behaviour predicted by the simple model. Dissociation of the calcium-indicator complex was found to be monoexponential under all conditions examined. The affinity for calcium of the three indicators generally increases with raising temperatures (Kdat 11.5 °C and 39.7°C (nM): 261, 180 for calcium green; 527, 323 for calcium orange; 201, 204 for calcium crimson) and pH (Kdat pH 6.42 and 7.40 (nM): 314, 226 for calcium green; 562, 457 for calcium orange; 571, 269 for calcium crimson). The changes of the thermodynamic dissociation constant are mainly caused by changes of the association rate constant. The temperature dependence of calcium binding to the indicators revealed that this process is entropically favoured at ambient temperature.